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Group Title: Bulletin of the Florida State Museum
Title: Studies on the evolution of box turtles (genus Terrapene)
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Permanent Link: http://ufdc.ufl.edu/UF00001509/00001
 Material Information
Title: Studies on the evolution of box turtles (genus Terrapene)
Alternate Title: Bulletin of the Florida State Museum ; volume 14, number 1
Physical Description: 113 p. : illus., map. ; 23 cm.
Language: English
Creator: Milstead, William W
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 1969
 Subjects
Subject: Box turtle   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 105-107.
General Note: Cover title.
Statement of Responsibility: by William W. Milstead.
 Record Information
Bibliographic ID: UF00001509
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltqf - AAA0818
notis - ACK3726
alephbibnum - 000443065
oclc - 00590576
lccn - 78628701

Table of Contents
    Front Cover
        Front page 1
        Front page 2
    Main
        Page 1
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Full Text



BULLET


IN


OF THE

FLORIDA STATE MUSEUM


BIOLOGICAL SCIENCES


Volume 14


STUDIES ON


Number I


THE EVOLUTION OF BOX TURTLES
(GENUS TERRAPENE)


William W. Milstead


A U
70. V.
F63 4b,
V./


UNIVERSITY OF FLORIDA


Gainesville
1969


/7-
52Za








Numbers of the BULLETIN OF THE FLORIDA STATE MUSEUM are pub-
lished at irregular intervals. Volumes contain about 300 pages and are not
necessarily completed in any one calendar year. Q,4


vok, L4


3 1262 04281 2122


SCIENCE
LIBRARY


Communications concerning purchase or exchange of the publication and all
manuscripts should be addressed to the Managing Editor of the Bulletin, Florida
State Museum, Seagle Building, Gainesville, Florida 32601.


Published, June. 10 -1969
'?


Price for this issue $1.50


UNIVERSITY

OF FLORIDA

LIBRARIES










COLLEGE LIBRARY












STUDIES ON THE EVOLUTION OF BOX TURTLES

(GENUS TERRAPENE)


WILLIAM W. MILSTEAD'


SYNOPSIS: Describes and analyzes important North American fossil and Recent
box turtle material. Characters investigated include osteological features of the
shell and skull as well as scutellation and color. Salient morphologic features,
past and present distribution, and evolutionary history of each of the recognized
taxa are discussed. No nomenclatorial changes are proposed.


STABLE OF CONTENTS

t\ ACKNOWLEDGEMENTS AND ABBREVIATIONS .................
ATERIALS AND METHODS ...................... ..................
TAXONOMIC INTERPRETATIONS
THE GENUS Terrapene -......
S THE CAROLINA GnouP ........ ............ ...
S Terrapene c. carolina ........ ......
T. c. putnami ..... ...... ----- .......... .....
T. c. major .....
T. c. bauri ............ .. ..
T. c. triunguis ... ......................................... -


T. c. yucatana ... ....- .................. -
T. c. mexicana ................ ....
T. coahuila ..... ......
THE OnNATA GROPr .......... ... .....-
Terrapene ornata longinsulae .........
T. o. luteola .................
T. o. ornata ..
T. nelsoni klauberi ........... .. .....
T. n. nelsoni ......... ................. ....... ---
LITERATURE CITED
TABLES ........... ..


15
.......... 21
........... 28
32
37
....... 41
.......... 45
54
72
........... 76
... ... 80
85
87
.......... 90
........... 94
S 100
102
........ 105
-. 108


'The author is Professor of Biology and Chairman of the Biology Department
at the University of Missouri-Kansas City. Most of his researches have been
evolutionary and ecological studies of amphibians and reptiles. This is his
first contribution to the Bulletin. Manuscript received 3 September 1968 Ed.

Milstead, William W. 1969. Sfru.t.. on the evolution of box turtles, (Genus
Terrapene). Bull. Florida State K .. vol. 14, No. 1, pp. 1-118.


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BULLETIN FLORIDA STATE MUSEUM


Y basic plan of this study was formulated at a meeting
,el..en Walter Auffenberg, Donald Tinkle, and myself at the Uni-
"rsity of Florida in January, 1959, where we compared specimens
of Texas fossils reported by me (Milstead, 1956) with Florida fossils
reported by Auffenberg (1958). At that time we decided that the
first step in understanding evolution in the genus Terrapene should
be a comprehensive study of living box turtles to discover osteo-
logical characteristics that could be used to distinguish the various
species and subspecies. We began by examining specimens from
the extremes of the subspecies ranges where there could be little
question of identification. The forms and areas considered in this
initial phase of the study were: T. carolina bauri, Dade County,
Florida; T. carolina carolina, New Jersey and New York City-Long
Island area; T. carolina major, Tallahassee, Florida, area; T. carolina
triunguis, south-central Texas; T. orata ornata, Oswego, Kansas area;
and T. ornata luteloa, Arizona. After characters were identified in
the initial approach, we planned to refine them by applying them
more generally to the subspecies ranges, and finally to apply the
refined characters to the fossils. Concentration was on osteological
features of the plastron, partially because plastral elements are more
frequently preserved as fossils than carapacial elements, and partially
because plastral elements appear to be less variable than carapacial
elements. Other than those of the plastron, the characters used
initially were those of the nature of the postorbital bar of the skull,
size, presence or absence of axillary scales on the carapace, shape
of the first central scute, flaring of the marginal scutes, and position
of the plastral hinge in relation to the marginal scutes. Other
characters were added as the work progressed.
Difficulties in packaging and shipping the many box turtle speci-
mens in the major collections made us decide early in the study that
it would be best to visit the various collections personally; this was
the procedure followed except in a few cases. Visits to the collections
also provided the opportunity to exchange views with other herpe-
tologists, and these exchanges yielded many valuable ideas and
suggestions, as well as considerable information on box turtle habits
and habitats. It also seemed advisable to visit areas where box
turtles had been collected in order to gain first hand information on
habitats. During the study I visited a number of fossil localities and
one or more localities for each of the living species and subspecies.
Efforts to collect personally at least one specimen of each of the
living forms, however, were not successful.


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Vol. 14







MILSTEAD: BOX TURTLE EVOLUTION


ACKNOWLEDGMENTS AND ABBREVIATIONS

Visits to museums in the United States and most of the field trips in the
United States and Mexico were supported by National Science Foundation
grants G19421 and GB1232. Visits to European museums and support during
the time the manuscript was in preparation were provided by a John Simon
Guggenheim Memorial Fellowship and a sabbatical leave grant from the Uni-
versity of Missouri-Kansas City. A 1962 field trip to the Mexican states of
Coahuila, Nayarit, and Sonora was supported by National Science Foundation
grant G23042. A small pen and pond for studies on captive turtles was built
with funds provided by the Kansas City Regional Council for Higher Education
and the UMKC Biology Department. A 1965 trip to Alamos, Sonora, Mexico,
was made possible by a UMKC Faculty Research Grant. I am grateful to
these institutions and organizations for their support.
I am indebted to numerous people for ideas and information obtained
through lengthy discussions of turtle evolution and of changing climatic con-
ditions during the Pleistocene. Foremost among the contributors were Walter
Auffenberg, the late Norman Hartweg, Claude Hibbard, Ernest Lundelius, Bob
H. Slaughter, and Donald Tinkle. I am also indebted to many people for
permission to examine material in their charge. The names of these people, most
of whom also contributed ideas and information, are given below with the
institution or collection with which they are associated:


AMNH American Museum of Natural History, Charles M. Bogert, Richard
G. Zweifel
ANSP Academy of Natural Sciences of Philadelphia, James E. B'dhlke
ASU Arizona State University, W. L. Minckley
BCB private collection of Bryce C. Brown
BMNH British Museum of Natural History, Alice G. C. Grandison
BUSM Baylor University Strecker Museum, Bryce C. Brown
FMNH Field Museum of Natural History, Robert F. Inger, Hymen Marx
KU Kansas University Museum of Natural History, William E. Duellman
MCZ Museum of Comparative Zoology, Harvard University, Ernest E.
Williams
MRHN Musee Royal d' Histoire Naturelle de Belgique, G. F. de Witte
NMS New Mexico State University, James Dixon (then at NMS)
RC private collection of Roger Conant
RMNH Rijksmuseum van Natuurlijke Historie, M. S. Hoogmoed
SM Senkenberg Museum, Robert Mertens, Konrad Klemmer
SMU Southern Methodist University, Bob H. Slaughter
TCW Texas Cooperative Wildlife' Collection, Texas A & M University,
W. B. Davis, Richard Bauldauf
TNW Tulane-Northwestern University Collection, Tulane University,
Harold Dundee
TT Texas Technological College, John S. Mecham
UCB Universi4' of California (Berkely), Robert Stbbins
UCM U .... ;r, of Colorado Museum, T. Paul Maslin
UF t-., .:r:ry of Florida (Florida State Mu.eur.i,. W. Auffenberg


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BULLETIN FLORIDA STATE MUSEUM


UF-RMJ University of Florida, R. M. Johnson field numbers
UMKC University of Missouri (Kansas City), James L. Vial
UMMP University of Michigan Museum of Paleontology, Claude W. Hibbard
UMMZ University of Michigan Museum of Zoology, Charles F. Walker,
Donald W. Tinkle
USNM United States National Museum, the late Doris Cochran, James
Peters
UT University of Texas, W. Frank Blair
VNHM Vienna Naturhistorishe Museum, Josef Eiselt

I am also indebeted to J. Douglas Walter for preparing the figures and
the final composition of plates, and to secretaries Maureen Arnold, Mary Alice
Crivello, and Toni Gregory for loyal service. I am very grateful to members
of my family for having endured my frequent absences from home, trips to
Europe and Mexico, and for having continuously shared their home with a
small herd of box turtles.



SYMBOLS
Several symbols are used consistently throughout the following report. In
most cases the symbols are composed of a numeral and one or more letters.
The numerals are sample numbers and the letters are abbreviations for taxonomic
identifications of the samples. (The symbol 3C, for example, refers to sample
number 3, composed of 53 specimens of Terrapene carolina carolina from New
Jersey.) The abbreviations are:


B T. carolina bauri
BM T. c. bauri x major
C T. c. carolina
CB T. c. carolina x bauri
C(B) T. c. carolina (with bauri
influence)
CMT T. c. carolina x major x
triunguis
Co T. coahulia
CT T. c. carolina x triunguis
C(T) T. c. carolina (with triun-
guis influence)
K T. nelsoni klauberi
L T. ornata luteola
Lo T. o. longinsulae
M T. c. major
MT T. c. major x triunguis
Mx T. c. mexicana
N T. n. nelsoni
*


P T. c. putnami
PB T. c. putnami x baud
PT T. c. putnami xt triunguis
R T. o. ornata (R is used to
avoid confusion between the
alphabetical O and the nu-
merial 0.)
RL T. o. ornata x luteola
R(L) T. o. ornata (with luteola
influence)
T T. c. triunguis
T(C) T. c. triunguis (with caro-
lina influence)
T(M) T. c. triunguis (with major
influence)
T(P) T.c. triunguis (with putna-
mi influence)
Y T. c. yucatana
x horizontal intermediate form
xt vertical intermediate form


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


MATERIALS AND METHODS
Box turtles are extremely variable morphologically, a fact first
noted by Barbour and Stetson (1931), and re-emphasized by Milstead
(1956) and Auffenberg (1958). No single characteristic can be
depended upon to identify a series of box turtles, and no series of
characteristics can be depended upon to identify a single box trutle
below the species level. It has been necessary, therefore, to use
many characteristics and to apply them to series of specimens drawn
together from various collections to form adequate samples of local
populations. An annotated list of the characters used is given below,
and the approximate localities of the samples used are shown in
figure 1. Three factors were given strong consideration in assembling
individual specimens to form samples: (1) to reduce errors caused
by ontogenetic influences on the characters, only specimens over
99 mm were used, (2) all specimens in any one sample are from the
same biotic province, and (3) all specimens in any one sample
are from localities as close together as possible. Unfortunately it
was necessary to be opportunistic in regard to the third point. The
10 specimens of T. ornata luteola from Brewster, Jeff Davis, and
Presidio counties, Texas (sample 54L), for example, come from a
much wider area than the 45 specimens of T. carolina carolina from
the Baltimore-Washington area (sample 5C). It would be much
more desirable to have a sample composed of 5% to 10% of the
entire adult population of any one decade collected within a radius
of 25 miles from a given point on a map, but this was not possible.
Although it is sometimes difficult to establish the number of individ-
uals represented in a sample of fossils, a total of at least 2,050 adult
box turtles were examined and included in the 87 samples shown
in figure 1 and Tables 2-4. Data from several hundred other speci-
mens were discarded because the specimens from which they were
obtained did not conform to all three criteria outlined above.

CHARACTERS STUDIED
In view of the abundance of box turtles over the eastern United
States, museums hold surprisingly few skeletons of them. Thus, no
statistically sound series of skulls has been examined for any one
form or character. Although skull characters are generally considered
among the most stable used in taxonomy, the high degree of varia-
tion found in other box turtle characters permits some skepticism
regarding the stability of those of box turtle kulls.


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MILSTEAD: BOX TURTLE EVOLUTION


POSTORBITAL BAR.- This is a span of several bones extending
from the posterior border of the orbit to the anterior border of the
tympanum. In Terrapene it is composed of the squamosal, anterior
edge of the quadrate, posterio-ventral portion of the postorbital, and
posterio-dorsal portion of the jugal. In the Carolina Group of box
turtles, the squamosal bone may be thick and broad (Figure 5B),
reduced to a thin bar of bone (Auffenberg, 1958, figure 8C; 1959,
figure 1B), present only as a span of cartilage, or absent Figure 5C).
Even when the squamosal is totally lacking, the posterior portions
of the postorbital and jugal bones retain their contributions to the
postorbital bar. These are seen (Figure 5C) as a posteriorly directed
bony process behind the orbit. In the Ornata Group, all traces of the
postorbital bar have been lost, the jugal and postorbital bones are
reduced in thickness, and the posterior border of the jugal-postorbital
junction is smooth (Figure 5D, E).
ANGULAR BONE. McDowell (1964) has noted that in the Ameri-
can box turtles (Terrapene) and other members of the testundinid
subfamily Emydinae, the angular bone forms the floor of the canal
for Meckels cartilage. Although this characteristic appears to be
stable in the two species of the genus Coura (amboinensis and tri-
fasciata) for which skeletal material is available, it varies in Terrapene
and Clemmys. One Terrapene carolina bauri, two T. c. triunguis,
one T. coahuila, one T. nelsoni nelsoni, and one Clemmys marmorata
had the angular excluded from contact with Meckel's cartilage.
BAsiocCIPrrAL. The subfamily Batagurinae has a strong lateral
process (batagurine process), which forms the floor of the recessus
scalae tympani, but the subfamily Emydinae lacks the process (Mc-
Dowell, 1964). No species of Terrapene appears to have the process,
but both species of Cuora examined do have it. Associated with the
batagurine process is a posterior extension of the mesial border of
the pterygoid. This process and the batagurine process, give the
batagurine turtles a much heavier and more solid bony armor on
the underside of the skull than is found in the emydines.
CAROTICOPHARYNGEAL FORAMINA. McDowell (1964) has related
Terrapene to Clemmys chiefly on the point that both genera have
enlarged caroticopharyngeal foramina. I found these foramina quite
variable in both size and location in the Terrapene and Emys speci-
mens I examined. Within only one subspecies, Terrapene carolina
carolina, did the size of the foramina vary from large (as in Clemmys)
to small (as in Emys) to absent.



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1969







BULLETIN FLORIDA STATE MUSEUM


FRONTAL. McDowell (1964) has noted that the frontal bone
enters the orbital margin in Terrapene and Clemmys, while in Emys
the frontal is excluded from the orbit by a strong contact between
the prefrontal and postorbital. I have found this character variable
in Emys and Terrapene. In Emys the association between the pre-
frontal and postorbital varied from a point-to-point contact (one
specimen) to a broad contact (most specimens), while in Terrapene
the association varied from no contact (most specimens) to a broad
contact (11 specimens). The specimens of Terrapene with a broad
contact included 2 T. carolina carolina, 7 T. c. bauri, 1 T. c. major,
and 1 T. nelsoni nelsoni.
JUGAL. McDowell (1964) found that Emys has the "lower end of
the jugal expanded inward along the posterior border of the maxilla
to meet the pterygoid," while Clemmys and Terrapene have the
lower end of the jugal narrowing to a point without meeting the
pterygoid. My investigations have shown that this character is useful
as a taxonomic tool, but that there are some variations of significance
in considering the relationships of the three genera. Most specimens
of Terapene, and all specimens of Clemmys, examined had a jugal
that tapered to a point without any inward expansion onto the
posterior border of the maxilla. But in 1 Terrapene carolina carolina,
10 T. c. bauri, 1 T. c. mexicana, 2 T. c. triunguis, 1 T. c. yucatana,
4 7'. coahuila, and 1 T. nelsoni nelsoni, the jugals were expanded
to cover about half of the posterior border of the maxilla. The one
specimen of T. carolina major examined had a complete contact
between the jugal and pterygoid, exactly as found in most specimens
of Emys. A number of skulls of Clemmys and Terrapene, particularly
those that were poorly cleaned, had a membranous bridge from the
lower end of the jugal to the pterygoid. Adult specimens of Emys
exhibited an osseous expansion of the jugal, but five juvenile speci-
mens showed only a membranous bridge, as found in Clemmys and
Terrapene. One juvenile Emys showed no contact between the jugal
and pterygoid, and one young adult showed only a partial contact.
Both of the latter specimens were fully cleaned, however, and mem-
branous bridges may have existed in life. Thus it appears that the
lower end of the jugal tends to become ossified in Emys, but tends
to remain membranous in Terrapene and Clemmys.
CERVICAL VERTEBRAE. -Members of the testudinid subfamilies
Emydinae and Batagurinae show a slight difference in the morphology
of the cervical vertebrae (McDowell, 1964). In Terrapene and other


Vol. 14







MILSTEAD: BOX TURTLE EVOLUTION


emydines, the 1st, 2nd, 3rd, and 4th joints between the centra of
the vetebrae are simple joints with a single condyle and socket, but
both the condyle and the socket expand progressively laterally until
the 4th joint has a bar-shaped condyle with a weakened medial area.
The 5th joint has a complete separation to produce a double condyle.
In Coura and other batagurines, the separation does not occur until
the 6th joint. This characteristic is somewhat subjective, in that
some specimens of Coura come very close to having double condyles
at the 5th joint, while some Terrapene specimens have poorly-
developed double condyles at the 5th joint.
CARAPACE LENGTH.- This is used throughout the study as an indi-
cation of size. It has some disadvantages in that it is only one para-
meter of size, but it is useful in supporting statements of relative size
(e.g. Terrapana carolina major is the largest living box turtle). Cara-
pace length was measured with calipers from the anterior edge of
the nuchal scute to the posterior edges of the 12th marginal scutes.
Ranges of sample averages are given in table 1, and the individual
sample averages are given in tables 2, 3, and 4.
CARAPACE SHAPE.- Four characteristics of carapace shape are
used: (1) whether round or elongate as seen in dorsal view; (2)
curvature, or general outline, of the carapace as seen in lateral view
(median saggital section); (3) highest point of the carapace, partic-
ularly as to whether it comes before the bridge (Ornata Group) or
behind the bridge (Carolina Group); and (4) sculpturing of the
shell, as, for example, the presence of a hump (or boss) on the
third central scute of T. carolina triunguis and depressions in the
posterior; pleural bones of T. carolina mexicana and T. carolina
yucatana. Differences in shapes of the various box turtles are shown
in figures 2 and 4-18.
FIRST CENTRAL ScuTE. Auffenberg (1958) used the shape of
the 1st central scute in dorsal view in working with Florida box
turtles, and the shape in lateral view was used by Milstead (1967)
and Milstead and Tinkle (1967) in working with the Ornata Group.
Although the shape of the 1st central in dorsal view shows extreme
variation (Auffenberg, 1958, Figure 12), most of the specimens
from some Floridian populations have a straight-sided scute, while
most of the specimens from other populations throughout the range
of the genus have something other than a straight-sided scute, usually
an urn-shaped scute similar to Auffenberg's (1958) Figure 12D, third
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BULLETIN FLORIDA STATE MUSEUM


FIGUnE 2.


Box turtle silhouettes. A-B, dorsal and lateral views, Terrapene c.
carolina, New York City area. C-D, dorsal and lateral views, T c.
carolina, Michigan. E, posterior view, T. c. carolina from almost any
area in its range. F, lateral view, T. c. bauri, Dade county, Florida,
G, lateral view of T. c. major, St. Joseph's Island, Florida. H-I,
lateral and posterior views, T. c. triunguis, Oklahoma. J, lateral view,
T. c. yucatana, Piste, Yucatan. K, lateral view, T o. ornata, Kansas
City, Missouri. L, lateral view, T. n. nelsoni, Pedro Pablo, Nayarit.


from left. In collecting data for this study, the shape of the 1st
central scute of specimens examined was recorded by a number
given in reference to Auffenberg's figure.
The shape of the 1st central scute in lateral view appears to
be an important character for distinguishing the various forms of
the Ornata Group and in distinguishing between the Ornata and
Carolina Groups. The Carolina Group has the 1st central elevated
at a steep angle, while the Ornata Group has it elevated at a low
angle. Some forms (e.g., T. nelsoni nelsoni) have such a low angle
that the anterior third of the carapace appears flattened, somewhat


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Vol. 14







MILSTEAD: BOX TURTLE EVOLUTION


reminiscent of acquatic members of the subfamily Emydinae. Un-
fortunately the importance of this character did not develop until
late in the study, and measurements of the angle of elevation referred
to later were taken from only a few specimens. They are, thus,
not to be relied upon as anything more than an approximate quan-
tification of a trait that can readily be seen (Figures 2 and 4-18).
The elevation of the 1st central scute actually represents the
elevation of the underlying neural and pleural bones, but in this
character and other characters of the carapace and plastron, the
bones have been ignored and measurements have been taken on
the scutes. This was done because preserved specimens, which con-
stituted most of the material examined, have the bones obscured by
the scutes. Fossil and skeletal specimens, on the other hand, show
the seam lines of the scutes on the bones.

AXILLARY SCALES. These are epidermal scutes that occur just
anterior to the bridge on the ventral, medial edges of the marginal
scutes. Terrapene usually has a single scute, while in Cuora the
scute is usually double. Auffenberg (1958) notes that the scute
is usually present in T. carolina major and T. c. putnami, and rarely
present in T. c. bauri. The present study has shown (Table 2) that
an auxiliary scale is present in 100% of the specimens of major
examined, in up to 91% of the specimens of one sample of T. c.
triunguis, in up to 80% of the specimens of one sample of T. c.
carolina, in 78% of the specimens of T. c. coahuila, and is present
in less than 20% of the specimens of T. c. bauri, T. c. mexicana, and
T. c. yucatana. When present in the Carolina Group, the scale is
usually on the 4th marginal, or occasionally overlies the adjacent
halves of the 4th and 5th marginals. The scale is present only rarely
in the Ornata Group, and usually overlies the 5th marginal when it
is present. Auffenberg (1958) noted that the size of the axillary
scale varied when it was present, but considered the scale to be an
important character only in terms of presence or absence. Milstead
(1957) treated it as enlarged (covering half of the ventral side of
the 4th marginal scute), reduced (less than half of the ventral side
of the fourth marginal scute), or absent. This treatment produced
the semblance of a dine around the Gulf Coast from Florida to
Texas, but if such a dine exists, it is only along the Gulf Coast.
No clinical relationship was found in other directions, and the data
were found to be more meaningful when the auxiliary scale was
treated simply as either present or absent.







BULLETIN FLORIDA STATE MUSEUM


MARGINAL SCUTES. Auffenberg (1958) notes that the degree to
which the marginal scutes flare outwards and upwards from the
carapace is important in recognizing the various box turtles of
Florida, and he presented data on both the radius of curvature
and the angle of flare for the turtles he studied. It now appears
that the degree of marginal flare is an important character when
applied to all members of the genus Terrapene. I gathered no quan-
titative data on this character during the present study, but I have
relied heavily on Auffenberg's data in comparing specimens visually.
Another character of the marginals appears to be of some use in
distinguishing the two species groups in the genus Terrapene. In
members of the Carolina Group, the shape of the 1st marginal scute
is normally rectangular, while in members of the Ornata Group,
it is usually irregularly oval or triangular (Milstead and Tinkle,
1967).

KEELS. An important distinction between the Carolina and
Ornata groups is a prominent mid-dorsal keel usually present on
the 2nd, 3rd, and 4th central scutes of members of the Carolina
Group. Although a keel is frequently present in some members of
the Ornata Group (60% of specimens of T. nelsoni nelsoni), it is
only weakly developed and usually limited to the posterior half of
the 3rd and anterior half of the 4th central scutes. The prominence
of the keel in the Carolina Group is frequently enhanced by a shallow
trough or groove on each side of the keel. Some members of both
species groups frequently have a lateral keel above the bridge. This
is generally associated with flaring marginal scutes anterior and
posterior to the bridge. The lateral keel is of some use in distin-
guishing between subspecies in both groups.

PLASTRAL HINGE. When a box turtle is viewed laterally, the
plastral hinge may be opposite the 5th marginal scute of the cara-
pace, opposite the seam between the 5th and 6th marginals, or
opposite the 6th marginal scute. Members of the Carolina Group
usually have the hinge oppositee the 5th marginal, while members
of the Ornata Group usually have it located more posteriorly. Within
the Ornata Group, T. o. ornata usually has the hinge opposite the
seam between the 5th and 6th marginals, while T. o. luteola usually
has it opposite the 6th marginal (Table 3).
PLASTRAL RATIOS. These include seven ratios: (1) anterior
lobe length/posterior lobe length, (2) intergular suture length/-


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


anterior lobe length, (3) interhumeral suture length/anterior lobe
length, (4) interpectoral suture length/anterior lobe length, (5)
interabdominal suture length/posterior lobe length, (6) interfemoral
suture length/posterior lobe length, and (7) internal suture length/-
posterior lobe length. The seam lengths were taken with calipers
on the mid-line of the plastron. In cases where the scute of one
side extended farther posteriorly than the scute of the other side,
measurements were taken from a point midway between the two, and
the next succeeding measurement began at the same point. The
length of the anterior lobe was obtained by adding the lengths of
the intergular, interhumeral and interpectoral seams, and the length
of the posterior lobe was obtained by adding the lengths of the
interabdominal, interfemoral, and internal seams. By this method
the length of each lobe is equal to the sum of its parts. This made
work with the ratios easier, and at the same time served to reduce
some of the error produced by the curvature of the plastron.
Because of the plastral curvature, a direct measurement of length of
either lobe by calipers yields a figure that is less than the sum of the
parts. The dorsal lip of the plastral hinge was not included in figures
recorded for anterior lobe lengths. It was omitted because it is
hidden by the ventral lip of the posterior lobe of articulated specimens
and cannot be measured. Samples of all of the living forms of the
genus Terrapene were studied with the sexes treated separately.
When it was found that no significant sexual dimorphism existed in
any of the plastrial ratios, the figures for the two sexes in all
samples were combined. This lack of sexual dimorphism greatly
facilitated work with fossil specimens, in which sex determination is
occasionally little more than guesswork.
Sample averages of plastral ratios are shown in Tables 1-4. The
importance of these ratios as taxonomic tools varies, but some gen-
eralizations can be made: (1) the plastral ratios are useful in dis-
tinguishing the various species of the genus; (2) they are also useful
in distinguishing the various subspecies, but in this respect they are
somewhat more useful in the Carolina Group than in the Ornata
Group; (3) anterior lobe ratios as a w:ole are more useful than
posterior lobe ratios; and (4) the most consistently important ratios
are those of the interhumeral and interfemoral seams. This last
generalization is related at least in part to the central location of
. these two seams on their respective lobes. They show their own
variations and also reflect changes in the other seams.
Some of the plastral ratios show definite dines around the Gulf






BULLETIN FLORIDA STATE MUSEUM


Coast from Florida to Texas in the Carolina Group (Table 2, and
Milstead, (1967). Generalized dines exist in the Ornata Group,
but the circumferential Gulf Coast dines are the only distinct ones.
They may be the result of coincidence, but the fact that the dines
do occur in more than one ratio may be used as additional evidence
of the close relationship between triunguis and putnami-major, as
evidence of the importance of the Gulf circumferential corridor
(Auffenberg and Milstead, 1965) in Pleistocene movements and
faunal exchanges of box turtles, or as evidence for both.
POSTERIOR LOBE. Apart from the seam ratios, the posterior plas-
tral lobe shows three characteristics useful in distinguishing members
of the Carolina Group from members of the Ornata Group. First,
males of the Carolina Group have a smooth to deeply concave pos-
terior plastral lobe (Figure 4D) while males of the Ornata Group
have a smooth lobe. Second, the posterior margin of the plastron
is rounded in the Carolina Group (Figure 4-14), but may be straight-
edged in the Ornata Group (Figures 15-18). Third, large specimens
of the Carolina Group sometimes show a deep indentation of the
lateral margin of the posterior lobe at the femero-anal seam. This
gives the plastron the appearance of being tri-lobed (Figures 10C;
12D, F).
DIGrrs. Two characters of the digits were used in reference to
Recent specimens of box turtles. First, in the Carolina Group, it
has been known since the original descriptions of T. c. bauri and
T. c. triunguis that some forms have three toes on each hind foot
while others have four. This has generally been thought to be a
highly variable character, and was ignored at the beginning of this
study. As work progressed, however, it was noted that the number
of toes appeared to be a more stable character than previously
thought. It is now known that this character is highly stable in
"pure" lines of box turtles, and varies only in populations of one
subspecies showing some influence of another subspecies. Most mem-
bers of the Ornata Group have four toes on each hind foot. Only an
insignificant number of individuals have three toes.
The, second character used in relation to digits is sexually dimor-
phic, Legler (1960) first noted that T. o. ornata, T. o. luteola, and
T. n. klauberi have the ability to extend the medial hind toe inward
to serve as a clasper during copulation. Milstead and Tinkle (1967)
noted that males of T. n. nelsoni have the same ability. Members of
the Carolina Group appear to lack this ability.


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


COLOR PATTERN. Coloration as a whole was generally ignored
during this study because fossils lack coloration completely and in
specimens preserved in spirits colors are generally faded. The one
exception was the recording of the color pattern for most of the
Recent specimens examined. Legler (1960: 654) states, "Personal
observations of interspecific and ontogenetic variation of color pat-
terns of box turtles has convinced me that a basic pattern of more
or less linear radiations is the one from which all other patterns
(including spots, blotches, rosettes, and unicolored condition) can
be derived, and that the radial patten is generalized and primitive
for Terrapene (possibly for all emyids and testudinids as well)." I
am in complete agreement with this conclusion of Legler's, but have
some reservations about one of his following statements, "I suspect,
however, that the pattern of a living species most closely approaching
that of the primitive ancestral stock of Terrapene is the pattern of
fine, wavy, dark radiations (on a paler background) present in
young examples of T. coahuila." I agree that a pattern of dark
radiating lines may have been the, or one of the, patterns exhibited
by early box turtles, but disagree with the implication that T. coahuila
is closely related to the ancestral stock of the genus. I think that
the pattern displayed by T. coahuila came to it through T. carolina
triunguis or T. carolina putnami.


TAXONOMIC INTERPRETATIONS
Recent years have seen increased interest in the Quanternary
and its twilight zone between zoology and paleontology (see e.g.
papers presented and cited in Wright and Frey, 1965). This has
created some problems in taxonomy as horizontally-developed terms
(e.g., species, subspecies, intergrade, isolation) have come into wider
use in a vertical sense. I think it advisable, therefore, to present my
interpretations of the lower taxonomic categories as they are used in
the following pages.
The most important taxon, of course, is the species, and my
definition is fairly simple: I regard a species as a group of organisms
recognizable (at least to each other) by definite characteristics, and,
in general, reproductively distinct from other groups of organisms
through biochemical, ethological, or morphological barriers. Abstract-
ly, I think of a species at any one moment in time as being repre-
sented by a circle that encompasses all of the possible allelic
combinations that can be transmitted by that particular group of


*T- .







BULLETIN FLORIDA STATE MUSEUM


organisms (the gene pool). In this sense a biotic community could
be represented by a handful of coins placed side by side on a
table. The limited area in which two coins contact one another
would represent all of the interrelationships between the two species
from predation to gene exchange. (The analogy is already weak at
this point and should not be carried further.)
Through time, I see the circle of any one species as a column
of variable diameter (relative to increases or decreases in the size
of the gene pool), which at its base merges with another column.
Once they have diverged, I regard the columns of two species as
being distinct in both time and space, but do not regard isolation
in either time or space as being by itself a criterion for recognizing
a species. Thus, I feel that one or more populations of a species may
become isolated in space because of changing environmental con-
ditions, or may appear to be isolated in time because of an incomplete
fossil record, but I do not consider these gaps in space and knowl-
edge as being by themselves reason for recognizing the isolated
populations as distinct species
Terrapene carolina mexicana, for example, considered as a dis-
tinct species until recently (Milstead, 1967), is isolated in space
from all other forms of the genus by unsuitable ecological conditions.
Its morphology, however, is very close to that of two other turtles
(T. c. triunguis and T'. c. yucatana) and apparently gene flow
occurred between the three within the last few thousand years.
That mexicana could evolve into a new species if it continues to
remain isolated is not denied, but it does not appear to have
developed morphological traits during its relatively short period of
isolation, and nothing guarantees that climatic factors will maintain
the isolation long enough for isolating mechanisms to arise. A good
example of isolation in time is provided by Terrapene ornata longin-
sulae. Its line to modern examples of the species has a gap from
the Aftonian interglacial stage to the Wisconsin glacial stage, but it
is almost impossible to distinguish T. o. longinsulae from the modern
T. o. luteola, and it is expected that fossils connecting the two will
eventually be found. There is no question that a species of box
turtles could have existed from Aftonian to Wisconsin times, because
the fossil record for Terrapene carolina is almost complete from
mid-Pliocene to Recent times.
The word "subspecies" by virture of the meaning of its prefix
refers to something less than a species, but this is a very poor
definition biologically, because it provides no lower limit, and it


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


has led to extensive misuse of the taxon. In some cases nomencla-
ture below the species level has been carried to the point of recog-
nizing local populations and even individuals as distinct subspecies.
Such extensive nomenclaturial recognition of genetic variation is not
useful to studies of evolution, and has precipitated frequent proposals
to eliminate the term "subspecies" from formal taxonomy. I feel that
the deletion of a term because it has been misused is equally as bad
as the misuse, because those who, through lack of understanding
of the goals of taxonomy, misused the first term will simply misuse
its substitute or another term. Furthermore, I feel that the term
"subspecies" when properly applied is very useful to studies of
evolution. Thus I define a subspecies as an ecological or geographical
grouping of organisms that is almost a species. By this, I mean
that the morphological or behavioral traits of a subspecies allow
it to be easily distinguished from other members of its species, but
it is still a member of that species through genetic exchange with
one or more of the other members, even though at times that gene
exchange may be interrupted (as in the case of T. carolina mexicana
above). The subspecies of T. carolina provide good examples of
subspecies that are "almost species." All but one of the forms con-
sidered in the following pages as subspecies have been treated as
distinct species by various authors within the last two decades.
What I consider an excellent example of the proper use of the
subspecies taxon is provided by Natrix sipedon in the San Jacinto
River of southeastern Texas and other rivers emptying into the Gulf
of Mexico. Natrix sipedon confluens is a large, heavy-bodied water
snake more than a meter in length with a pattern of broad bands
and a round tail. It lives along the San Jacinto River in areas of
fresh water, and spends most of its time on the shore. Natrix sipedon
clarkii, on the other hand, is a small, slender water snake about
half a meter in length with a pattern of four narrow stripes and a
laterally flattened, oar-like tail. It lives in the Gulf of Mexico and
spends most of its time in the water. A person seeing the two for
the first time would not hesitate to call them different species, but
in the brackish water at the mouth of the San, Jacinto River, the
two snakes come together and interbreed freely to produce intergrades
that are intermediate in size, body form, tail shape, and color
pattern. The latter presents the most obvious intermediacy. The
bands of confluens and the stripes of clarkii come together in a
decorator's nightmare of bands, stripes, bands that trail off into
stripes, and stripes that run together to form bands.






BULLETIN FLORIDA STATE MUSEUM


It would be unreasonable to demand that all named subspecies be
as distinct as the two water snakes, but it would not be unreasonable
to demand that all subspecies be as distinct as those of the box
turtles. A simple test of a subspecies would be to consider it as a
species. Is this sample sufficiently distinct from its closest relatives
to be considered as a separate species? If the answer is affirmative,
the sample in question may be considered as a separate species
or as a subspecies, depending largely, but not entirely (see discussion
of T. c. mexicana above), on the amount of gene flow between the
sample population and closely related populations. If the answer
is negative, the sample in question may represent something less
than a subspecies. Obviously this test will not serve as a panacea
to cure all of the ills of lower-category taxonomy, but if it is used
even loosely it will put a stop to some of the "hair-splitting" that
has long cluttered biological literature and been a nuisance in studies
of evolution.
Abstractly I visualize subspecies as polygons with varying degrees
of contact between each other (to represent varying degrees of
genetic exchange) within the circle that represents the species.
Isolated subspecies can be represented by small circles within the
large circle. The present-day forms of the genus Terrapene, there-
fore, may be represented by a number of small circles and polygons
contained within four large circles as shown in figure 3,A.
Vertical representation of subspecies is more difficult because
the nature of subspecies makes them more easily illustrated horizon-
tally. A subspecies is, in a sense, a sub gene-pool, because certain
genetic combinations are expressed more frequently than others, but,
if there are enough individuals, a subspecies may contain the gene
FIGURE 3. Suggested relationships of box turtles: A at present, B through time.
Outer circles in A and columns in B represent species: (left to right)
nelsoni, ornata, carolina, and coahuila. Small circles, semicircles,
triangles, and polygons within the larger circles of A represent rela-
tionships between subspecies showing relative amounts of territory
occupied by each subspecies and relative amounts of contact between
subspecies. Ranges of carolina-bauri and major-bauri intergrades
are added to the bauri area, carolina-triunguis and major-triunguis
intergrade areas are added to triunguis, and ornata-luteola intergrade
areas are added to luteola. Solid lines in B, except for those shown
for T. nelsoni, are vertical relationships suggested by fossils. Dash
lines and all lines for nelsoni in B are vertical relationships suggested
by occurrences of similar traits, but without fossil substantiation.
Letters are symbols for species and subspecies. See text for additional
explanation.


Vol. 14





MILSTEAD: BOX TURTLE EVOLUTION


A.-




N K
D. I ****\'" J>-


( /

/


,, TO EMYS
/ TO MODERN


CLEMMYS ANCESTOR
'y -






BULLETIN FLORIDA STATE MUSEUM


pool of the species. That is, it is possible that the number and kind
of allelic combinations that can be produced by the species as a
whole may not exceed the number that can be produced by one or
more of its subspecies. This means, ignoring the possibility of non-
adaptive genetic drift, that the particular phenotype of a subspecies
is maintained by natural selection, and that under changing environ-
mental conditions one subspecies through successive generations
could change into another by genetic recombinations, or into a new
subspecies by new combinations. Or, in other words, subspecies,
unlike species, are fully reversable and reproducible. A young
species with two newly-formed subspecies could be represented
accurately by two small vertical columns within a larger vertical
column, but representation of an older species with several subspecies
and a turbulent history would require a piece of sculpture put
together with a number of pastel colors to show reversals, divergence,
convergence, intergradation, etc. Inaccurately, however, evolution in
Terrapene (as reconstructed below) can be illustrated by a series of
intersecting lines (used to represent columnar polygons) as shown
in Figure 3,B.
At times in the past, it has been argued that subspecies are only
two dimensional; i.e. they can be recognized only in a horizontal
sense. The nature of the great number of specimens and the amount
of information now being accumulated from the Cenozoic offer a
material defeat for the argument, but it should have been defeated
on philosophical grounds long ago. An individual after birth or
emergence from an egg has a life expectancy ranging from a few days
to a century or more, depending upon its species, health, activity,
and genetic potential. Although the longest individual life spans
are insignificant in terms of geological time, a subspecies would
ordinarily be expected to have a life span that brackets the life
spans of many individuals. In forms with long-lived individuals, the
subspecies life span could certainly be significant in terms of geologic
time.
A subspecies is recognized by a certain phenotype shared by the
majority of individuals in ,a definite geographical range or ecological
niche. Horizontally a subspecies is recognized as long as its pheno-
type can be recognized, and in my opinion, this rule of thumb
applies equally well vertically. There are important biological dif-
ferences between horizontal and vertical distribution, but in general,
those differences are of the same order of magnitude, and do not
interfere with the convenience of using the subspecies taxon in both

g.
Ik-c


Vol. 14


! ,







MILSTEAD: BOX TURTLE EVOLUTION


senses. It is important, however, to distinguish between the horizon-
tal and the vertical intermediate forms, and I have done this above
(under symbols) and in the following pages by using x for horizontal
intermediates and xt for vertical ones. Thus, turtles intermediate
between the modern Terrapene c. major and the modern T. c. triun-
guis are identified as T. c. major x triunguis, while those intermediate
between the extinct T. c. putnami and modern T. c. triunguis are
identified as T. c. putnami xt triunguis.
Although I have presented two cases in the following pages
where the use of the tetranomial might be justified, I do not feel
that anything below the trinomial is very useful. With the refined
techniques of today and the aid of computers, it is possible to
divide any population of a subspecies into finer and finer groupings,
ultimately ending with the individual. Certainly such detailed studies
of variation are useful in understanding evolution, particularly in
identifying traits that show similar degrees and directions of evolu-
tion, but I do not feel it is particularly useful or necessary to recognize
such divisions formally beyond the trinomial. Additional subdivision
brings about the dissolution of Linnaeus's greatest contribution to
taxonomy: a reasonable degree of assurance coupled with maximum
convenience.

Terrapene Merrem (1820)
DEFINITION AND COMPOSITION.
The genus Terrapene is included in the subfamily Emydinae of
the Family Testudinidae, and displays the major features of both
the subfamily and family. McDowell (1964: 277) describes the
salient morphological traits of the genus as follows:
jugal tapering to a point ventrally, not in contact with pterygoid, not excluding
maxilla from border of inferior temporal fossa; frontal entering orbital margin;
posterior palatine foramen little, if at all, expanded; caroticopharyngeal foramen
large, on pterygoid-basisphenoid suture, or connected to it by a short suture; plas-
tron with a hinge between hyoplastron and hypoplastron; plastron connected to
carapace by suture, the buttresses,.absent; cltv-al bursa. very small or absent.
Members of the genus are predominantly terrestrial in habitat, but
variations in habitats range from the aquatic or semi-aquatic T.
coahuila to the desert-inhabitating T. o. luteola. All members of
the genus are omnivorous. As presently known, the genus is limited
in distribution to North America (Milstead, 1965) where it is widely
distributed east of the cordilleras. Only on species (T. nelsoni)


1969








BULLETIN FLORIDA STATE MUSEUM


has its distribution west of the cordilleras. One specimen of T. ornata
(AMNH 73720) has been recorded from the west coast of Mexico,
but its natural occurrence there needs substantiation.
The living and fossil members of the genus may be divided into
two species groups on the basis of a number of morpholigical
characteristics. These were defined by Milstead and Tinkle (1967).
Completion of this study has provided data for some refinements
and additions, and it seems advisable to present the new version.
although it does not differ markedly from the original:


ORNATA GROUP


1. Postorbital bar usually
present, although the central
portion (squamosal bone) may
be cartilaginous; when squamosal
is absent, postorbital and jugal
bones have posteriorly directed
processes (Figure 5, B-C).

2. Inner toe of male not capable
of being turned inward.


3. Highest part of carapace
posterior to hinge
(Figures 4-14).


4. First central scute elevated at
a steep angle (50 or more);
anterior third of carapace
rounded or tapering gradually
upward posteriorly.

5. Posterior margin of plastron
rounded (Figures 4-14).



6. Lateral margin of plastron
may be indented at the
femero-anal seam (Figures
10, C; 12, D,F).

7. First marginal scute usually
rectangular in shape.


Postorbital bar absent; posterior
border of postorbital bone
smooth (Figure 5, D-E).





Inner toe of male capable of
being turned inward at sharp
angle to foot.

Highest part of carapace at or
anterior to hinge except in
some males of T. n. nelsoni
(Figures 5-18).

First central scute elevated at
a low angle (45" or less);
anterior third of carapace may
be distinctly flattened
(Figures 15, C; 18, A).

Posterior margin of plastron
either rounded or straight,
frequently straight (Figures
15-18).

Lateral margin of plast:on
usually entire.



First marginal scute usually
irregularly oval or triangular
in shape.


CAROLINA GROUP


Vol. 14







MILSTEAD: BOX TURTLE EVOLUTION


8. Posterior lobe of plastron
in males varies from smooth
or only shallowly concave to
deeply concave.

9. Carapace elongate except in
some T. carolina carolina.



10. Carapace rounded dorsally.
General appearance in both
sagittal and cross sections
is of a highly vaulted
carapace. T. coahuila, one
of the flattest members
of the genus is an exception
to this.

11. Axillary scale frequently
present, and usually on the
fourth marginal scute.


12. Interhumal seam long
(averaging 18% to 33% of
the anterior lobe length;
see Tables 1, 2).'

13. Interfemoral seam short
(averaging 10% to 21% of
the posterior lobe length;
see Tables 1, 2).1

14. Three or four toes on
each hind foot, dependent
upon the species and
subspecies being considered.

15. Hinge usually opposite
the fifth marginal scute
when specimens are viewed
laterally.


16. A mid-dorsal keel is
usually present and prominent.


Posterior lobe of plastron
in males smooth or only
shallowlv concave.


Carapace generally round or
oval except in T. nelsoni
nelsoni and some T. nelsoni
klauberi.

Carapace flattened dorsally.
General appearance in both
sagittal and cross sections is
of a flat turtle, although
height in proportion to length
in T. ornala ornata may be
greater than in some forms of
the Carolina Group.

Axillary scale usually
absent, but usually on the
fifth marginal scute, when
present.

Interhumal seam short
(averaging 11%, to 19% of the
anterior lobe length; see
Tables 1, 3).'

Inferfemoral seam long
(averaging 16% to 238 of the
posterior lobe length; see
Tables 1, 3).'

Usually four toes on each hind
foot in all species and sub-
species; three toes occur very
rarely.

Hinge usually opposite the seam
between the fifth and sixth
,marginal scutes or opposite the
sixth marginal scute whin
spea-nens are viewed laterally.

When present, a mid-dorsal keel
is only weakly developed.


'Forms of the two species groups in which percentages for this character over-
lap are not contiguously distributed at present (Figure 1, Tables 2 and 3).







24 BULLETIN FLORIDA STATE MUSEUM Vol. 14

The 16 characters are grouped in sequence to facilitate identi-
fication: numbers 1-3 may be applied to single specimens, 4-11 may
be applied with discretion to single specimens or small series, and
12-16 require good series of specimens. In each of the three groupings
(1-3, 4-11, 12-16), the characters are listed in what I consider to be
order of decreasing importance and/or utility in reference to the
species groups.
Application of these characteristics to the. specimens from which
they were drawn yields the following arrangement of species and
subspecies into the two species groups:

CAROLINA GROUP ORNATA GROUP
T. carolina bauri T. nelsoni klauberi
T. c. carolina T. n. nelsoni
T. c. major T. ornata ornata
T. c. mexicana T. o. longinsulae (extinct)
T. c. putnami (extinct) T. o. luteola
T. c. triunguis
T. c. yucatana
T. coahuila

ORIGIN AND AFFINITIES
The oldest known fossils of the genus are of Pliocene age. They
are fully differentiated as to both generic characters and species
group characters, and thus give no clues to the origin either of
the genus or of the species groups. The oldest fossil of the Ornata
Group (T. o. longinsulae) is of middle Pliocene age, as are the
oldest fossils of the Carolina Group (T. c. putnami). Although the
fossils provide no definite clues, it seems best to assume that the
Omata Group evolved from the Carolina Group. It might be sug-
gested that the converse possibility was the case, but this thesis is
rejected because: (1) the Carolina Group would have had to de-
velop a posturbital bar during the process; and (2) members of
the Ornata Group are among the most xeric-adapted species of
emydinid turtles, and a mesic or hygric-adapted ancestor to the
Carolina Group seems mandatory. Another possible hypothesis is
that the groups evolved from a common ancestor. In any case the high
degree of development of T. carolina putnami and T. ornata longin-
sulac by middle Pliocene times indicates that the genus and both






MILSTEAD: BOX TURTLE EVOLUTION


of the species groups must have had their origin in Miocene or
pre-Miocene times.
A description of a common ancestor for both species groups can
be drawn easily from the Pliocene and early Pleistocene fossils
(T. ornata longinsulae, T. carolina putnami, and T. c. carolina) and
from trends and parallelisms in various characteristics that seem
evident from my interpretations of evolution in the two groups
given in the following pages. Such an ancestor would have been
a medium-sized box turtle, 130-150 mm in carapace length; round
in shape, although some may have had a tendency to be elongate;
relatively flat in carapacial curvature; a weak mid-dorsal keel poste-
riorly was present in some; marginal scutes were generally non-
flaring, but some may have had a low degree of flare; plastral hinge
was located opposite the seam between the 5th and 6th marginal
scutes; the posterior margin of the plastron was rounded; the inter-
humeral and interfemoral scutes were long (averaging 30% or more
of their respective lobe lengths); the posterior plastral lobe of males
was smooth or only shallowly concave; the postorbital bar was solid
and broad in most, but some individuals had varying degrees of
reduction; each hind foot had four toes; an axillary scale was
present in some, probably overlying the seam between the 4th and
5th marginals; the color pattern in most was probably a pattern of
dark radiating lines, but some had light lines developed between the
dark lines, some had uniform coloration, and some may have had a
tendency toward melanism. The ancestral turtles were probably
marsh and moist-meadow inhabitants in central North America in
the ecotone between the eastern forests and the western plains.
The necessity of depending heavily on modern turtles to construct
a description of the common ancestor yielja, picture of the ancestor
as it was on the point of ev6idnig-Tnto the forest-inhabiting T.
carolina on one hand and the grassland-inhabiting T. ornata on the
other. How much evolution and how much time were required to
get the common ancestor to this point depend largely on the group
to which the genus Terrapene is related. Of the genera that seem
to be closest to Terrapenermorphologically, the Asiatic genus Cuora
seems at first glance to be the closest. Modern forms of the genus
Cuora display a plenotype that is almost an exact match with the
phenotype of the ancestral Terrapene described above, but in evolving
from Cuora, Terrapene would have had to change a number of
major features in the skeleton, including: resorption of the bata-
gurinid process into the basioccipital, resorption of the longitudinal






BULLETIN FLORIDA STATE MUSEUM


flange on the prearticular, movement of the double condyle on the
6th vertebral centrum anterior to the 5th centrum, and reduction
of the superacaudal scutes to the extent that they fall short of the
suture between the pygal and suprapygal. These four differences
between the two genera appear to be the most important because
they constitute the major differences between the subfamilies Emy-
dinae and Batagurinae (McDowell, 1964).
I examined more skeletons of Terrapene and Cuora than McDowell
did in order to test the stability of the first three of the four
characters in particular reference to these two genera. I consider
the first three of the four characters as being the most important
because they have to do with the axial skeleton rather than with
the shell. My examination was made because there is always the
possibility that one or both of the subfamilies had a polyphyletic
origin, and that the characteristics of the subfamilies are the result
of convergent evolution. Failure of the three traits to be exhibited
appropriately in numbers of specimens, or even extensive variation
in the traits, would be sufficient grounds for suggesting that the two
subfamilies are artificial divisions based on convergent characters.
Aside from the main goal of this study in seeking generic affinities
for Terrapene, two genera resembling each other as closely as do
Terrapene and Cuora would seem to be the logical place to look for
weaknesses in the characters.
The greatest variation in the three traits was found in the longi-
tudinal flange of the prearticular. In Terrapene a flange existed in
several of the 67 specimens examined, and it vas long enough in 5
specimens to exclude the angular from contact with Meckel's cartilage.
No specimen of Cuora lacked the flange or failed to have it exclude
the angular. Thus, of a total of 86 Cuora and Terrapene examined
only 5 (5.8%) exhibited a significant deviation from the expected.
Although, as noted above, the position of the first double condyle
in the cervical vertebrae is a somewhat subjective characteristic, it
appears to be more stable than the preceding character. The presence
or absence of the batagurine process appears to be the most stable
of the three characters. The process was present in all batagurines
examined and was missing aJl emydines. The only variations
noted were those of size, shape, and position of the process in the
batagurines.
It seems best, therefore, to conclude that no relationship exists
between the American and Asiatic box turtles, and that their close
resemblance is the result of convergence. As noted above, the re-


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


semblance is superficial. Only one trait possessed by both, the
hinged plastron, would require major genetic rearrangements (in
both soft and hard parts) in order for convergence to have occurred.
Although it would seem to require less genetic change to make a
Terrapene skeleton out of a Cuora skeleton than it would for both
genera to produce a hinge, this may not be true when all the
differences between the two genera are considered, and it must also
be remembered that both genera were probably under vigorous
selective pressure to develop the hinge. In assuming a terrestrial
habitat, turtles could follow only a few courses to protect their
soft parts: (1) develop a plastral hinge to enable the plastron to
be drawn up against the carapace, (2) develop a carapacial hinge to
enable the carapace to be lowered against the plastron, (3) develop
armored plates on the appendages, (4) reduce armour to allow
greater and more rapid movements, and (5) combinations of the
first four. Several otherwise unrelated groups could be expected to
solve the problem in the same way. Legler (1960) and McDowell
(1964) concluded previously that a hinged plastron arose indepen-
dently in several groups of terrestrial turtles.
Emydoidea is a North American emydine genus which also re-
sembles Terrapene, but the resemblance is between modem forms of
the two genera, and is not so close as the resemblance between the
modem forms of Cuora and the projected ancestral form of Terrapene.
Emydoldea and Tae petmal differ in major features of the skeleton,
which relate Emydoidea to the aquatic Deirochelys (Tinkle, 1962;
McDowell, 1964). Thus, the Emydoidea-Terrapene resemblance ap-
pears to be another case of convergence.
Clemmys and Emys are two emydine genera to which Terrapene
appears to be closely related through possession of the same major
skeletal features, although neither resembles Terrapene as closely as
do Cuora and Emydoidea. Of the two, Emys (Africa, Asia, and
Europe) more closely resembles both the proposed description of the
ancestral Terrapene and the modem forms of Terrapene than does
Clemmys (North America). This resemblance is seen in the posses-
sion of a plastral hinge, in adsorption of the plastral buttesses, and
I similar shapes of the posterior plastral lobes and pl htral scutes.
.-Jc;a wIll ( 10 Ttonn ldered Terrapene an offshoot of ClemnHs ,d
because both genera differ from Emys by having large carotico-'
pharyngeal foramina, but my own investigations show these foramina,
vary in size in all three genera. Two other characters, the contact
een the jugal and the pterygoid and the.contact between the
Z*N7' -






BULLETIN FLORIDA STATE MUSEUM


prefrontal and postorbital, also exhibit extensive variation. I suggest
that both Terrapene and Emys evolved from a common ancestor
that evolved from Clemmys in either Asia or North America, that
the common ancestor had the traits that all three genera hold in
common plus the beginnings of the traits that unite Terrapene and
Emys apart from Clemmys, and that all three genera subsequently
developed the traits that now distinguish them.
The two species groups of the genus Terrapene and suggested
evolutionary lines within those groups are discussed below. Specula-
tion on the origin of the genus Clemmys lies outside the scope of
this study.
The following skeletal specimens were examined with particular
reference to the subfamilial and generic characters discussed above:

BATACUrINAE
Cora amboinensls, BMNH 48.10.31.14, 51.11.10.76, 67.4.2.145, 71.9.1.52;
MRNH 4544, 4870; RMNH, 2 unnumbered skeletons; SM 32973-5; USNM
78128, 104345, 129253; VNHM 1799-1908
Coura trifasciata, VNHM 1785.
Cyclemmys dentata, BMNH 48.10.31.15, 67.3.5.24, 68.4.3.153, 97.11.22.3;
KU 47170.

EMTDINAE
Terrapene carolina baur, KU 20506, 20508-16.
T c. carolina, BMNH 58.12.30.2, 59.9.6.435, 1900.7.12.3, 1900.7.12.6; KU 2846,
2850, 2854, 2870, 16383-4, 16386-7, 16389, 16393; RMNH, 3 unnumbered
skulls; SM 29974; VNHM 1775-7.
T. c. major, UMKC 0502.
T. c. mexicana, KU 24075, 47902.
T. c. triunguis, KU 48264, 48266-73, 48276.
T. c. yucatana, KU 71778.
T. coahuila, KU 46924-27, 51432, 92623; UMKC 0496.
T. n. nelsoni. KU 92680-31; UMMZ 128400; UF 27188.
T. o. omata, KU 2844, 2860, 2866, 2901, 8588, 8540-1, 5033, 6862, 22969.
Clemmys guttata, KU 1114; VNHM 1723-4.
Clemmys Insculpta, KU 2843; VNHM 1725.
Clemmys mamorata, VNHM 1731, 1733.
Clemmys muhlenbergi, VNHM 1730.
Emys orbicular, VNHM 32-4, 37-9, 105-7.


'n; O CAROLINA GROUP


This group includes two species: Terrapene carolina, with one -
extinct and six living subspecies distributed over eastern North
America, and Terrapene coahuila, which is known only from a bolson
in central Mexico. Morphological differences between the two species


Vol. 14


1
-a


IA






MILSTEAD: BOX TURTLE EVOLUTION
a


are discussed under T. coahuila.
In general the Carolina Group may be considered forest-inhabiting
The one exception is T. coahuila, the only known aquatic member
of the genus, and I presume that it evolved from a forest form.
T. carolina carolina inhabits the northeastern deciduous forests of
the United States in the Carolinian biotic province of Dice (1943),
and because of this distribution in relation to the glacial periods,
it vas apparently the most geographically stable member of the genus
during the turbulent conditions of the Pleistocene epoch. While other
forms of the genus seem to have undergone one or more important
range shifts, which set the stage for isolation and speciation, T. c.
carolina appears to have lasted out the Pleistocene in almost the
same geographic range it occupies today, with only minor fluctua-
tions of range relative to expansions and contractions of the deciduous
forests. T. c. bauri, T. c. mexicana, and T. c. triunguis occupy mixed
pine and deciduous forests in their respective ranges in the United
States and Mexico, and T. c. yucatana inhabits tropical scrub forests
on the Yucatan Peninsular. T. c. major occupies palmetto-pine forests
and coastal marshes along the northern coast of the Gulf of Mexico.
Trees in the habitat of major may be close together or widely
scattered, and there may be relatively open areas with very few
trees. Underbrush is usually thick with dense stands of palmettos,
and frequently the forest floor has pools of water. The habitat of
the extinct T. c. putnami is presumed to have been the same as, or
similar to, the habitat of T. c. major.
The earliest known representative of the Carolina Group is T.
c. putnami from middle Pliocene deposits in Florida. T. c. carolina
appeared in late Blancan times, T. c. bauri appeared during the
early Rancholabrean, T. c. triunguis evolved in the Rancholabrean,
and T. c. major is an extension of T. c. putnami into the Recent
era. T. c. mexicana, T. c. yucatana, and T. coahuila are known only
from the Recent.
At present we have no clues to the origin of either T. c. putnami
or T. c. carolina, although carolina may have evolved from putnami
in the interval between the first appearance of putnami and the
first appearance of carolina (Aftonian4iABliiWal of the Pleistocene
in Florida). No evyience either supports or denies this thesis, and
theoretical arguments can le presented on both sides. It seems best
for the present to ignore the problem, and simply note that in the
early Pleistocene the Carolina Group was represented by two forms:
T. c. carolina, an upland, forest-inhabitating form that lived east of






BULLETIN FLORIDA STATE MUSEUM


the Appalachian Mountains; and T. c. putnami, a palmetto-pine-forest-
inhabiting form that lived along the Gulf Coast and west of the
Appalachian Mountains. The two forms presumably came into con-
tact and intergraded in Florida during a time of low sea levels in
a glacial stage. T. c. bauri is presumed to have evolved from these
intergrade populations.
Following the initial emergence of the Florida peninsula, high
Pleistocene sea levels divided Florida into a series of islands, and
it is suggested that these provided the physical mechanism for the
isolation of the carolina x putnami populations that evolved into
bauri. High Pleistocene sea levels also caused extensive embayments
along the Mississippi River at times, and these or some other barrier
divided putnami into eastern and western populations. The western
populations ultimately evolved into triunguis, and the eastern ones
into major. The evolution of major is presumed to have differed
from that of bauri and triunguis in that it apparently did not involve
the appearance of new characters through mutation or recombination,
but appears to have resulted from the swamping of some putnami
characteristics through intergradation with carolina and secondary
intergradation with bauri and triunguis.
The western populations of putnami that ultimately became tri-
unguis may have been the source from which the Mexican box
turtles evolved. It is suggested that at times in the Pleistocene
T. carolina ranged around the Gulf of Mexico from Florida to Yuca-
tan, and that T. c. yucatana evolved from a population of T. c.
putnami or T. c. putnami xt triunguis that became isolated on the
Yucatan Peninsula in pre-Sangamon or Sangamon times. During the
Wisconsin, trunguis and yucatana came into contact and intergrada-
tion occurred. Isolation of the intergrade populations, first from
yucatana by rising sea levels and then from triunguis by arid con-
ditions in northern Mexico, in post-Wisconsin times marked the
beginning of T. carolina mexicana. I suggest further that the evolu-
tion of T. coahuila was similar to that of T. c. yucatana in that it
appears to have begun with the isolation of a population of T. c.
putnami or T. c. putnami xt tridungq,
The existing o ssils of the (arolhna Gneurp leave little doubt
that T. c. carolina ad -T; c. putnami evolved before or in the early
FIGUrc 4. Terrapene carolina caolina. A, Living sricmen, Long Island, N. Y.
B, AMNH 6406, Massachusetts. C, UMMZ S443, Massachusetts.
D, AMNH 71292, New Jersey. E, UMMZ 78519, Michigan. *"
UMMZ 53003, Michigan. G-H, UMMZ 40833, Michigan. .4


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


D -. A .


41

-4*


i




-.


4Qdk"l.,.
MIN






BULLETIN FLORIDA STATE MUSEUM


Pleistocene, while bauri, major and triunguis evolved during the
Pleistocene. Evolution of the Mexican members of the group as
given above and in the following pages, however, is largely specula-
tion. Additional fossil material may show that putnami evolved from
yucatana or coahulia rather than vice versa. These possibilities and
reasons for rejecting them at present have been given more detailed
consideration in discussions of yucatana, coahuila, and the Ornata
Group.
Terrapene coahuila and the seven subspecies of T. carolina are
discussed in greater detail below. The distribution of members of
the Carolina Group are given in Figure 1, plastral ratios and other
data on the group are given in Tables 1, 2, and 4, and representatives
of the group are shown in Figures 4-14.


Terrapene carolina carolina (Linnaeus)
Figure 4; Table 2 (1-14)
Testudo carolina Linnaeus, 1758, Syst. Nat., ed. 10, 1:198.
Terrapene carolina Bell, 1825, Zool. Jour., 2:309.
Terrapene carolina carolina Stejneger and Barbour, 1917, Checklist N. Amer.
Amphib. & Rep., ed. 1:115.
Testudo carinata Linnaeus, 1758, Syst. Nat., 1:198.
Testudo incarcerata Bonnaterre, 1789, Tabl. Encycl. Meth., Erp.: 29.
Testudo incarcerata-striata Bonnaterre, 1789. ibid.
Testudo clausa Gmelin, 1789, Syst. Nat., ed. 13, 1:1042.
Testudo virgulata Latreille, 1801, Hist. Nat. Rept, 4:100.
Emys schneideri Schweigger, 1814, Konigsberg. Arch. Naturg. Math., 1:317, 442.
Monochda kentukensis Rafinesque. 1822, Kentucky Gazette, Lexington, 1 (21) :5.
Terrapene maculata Bell, 1825, Zool. Jour, 2:809.
Terrapene nebulos Bell, 1825, ibid:310.
Emys kinosternoides Gray, 1831, Syn. Rept., pt. 1:32.
Ciatudo virginea Aqassiz, 1857, Contrib. Nat. Iist. U.S., 1:441; 2:pl. 4, figs.
17-19, pl. 7, figs. 10-14.
Terrapene eurypygia Cope, 1860, Ext. Batrach., Reptilia, Aves, N. Amer.: 124.
Terrapene eurypygia Hay, 1902, Proc. Acad. Nat. Sci. Phila.: 385.
Terrapene formosa Hay, 1916, Florida State Geol. Surv., 8th ann. rept.: 39-76.

RECOGNTrON FEATURES: One or more of the plastral ratios of
T. c. carolina slha~n in Tables 1 and 2 distinguish it from ea. ;If
the other members d44r e species. The presence of four toes on
each hind foot further distinguishes carolinaif bauri,, mexicana,
and triunguis, and its relatively short carapace length further dis-
tinguishes it from putnami,, major, mexicana, and yucatana. The
deeply concave plastrons of male carolina separate them from males
--4k

T .


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


of mexicana, triunguis, and yucatana. The shape of carolina in
lateral view (Figures 2, 4) distinguishes it from every other sub-
species except major and putnami.
PRESENT DISTRIBUTION: -Cumberland and Allegheny plateaus
eastward. North of the Ohio River it extends westward to Lake
Michigan (Figure 1). Intergradation with triunguis occurs along
the Ohio and Mississippi Rivers and south of the Appalachian Moun-
tains east of the Mississippi. Intergradation with bauri occurs in
eastern Georgia and northeastern Florida, and simultaneous inter-
gradation with major and triunguis occurs in southwestern Georgia
and southeastern Alabama. The intergrades are considered in the
discussions of bauri and triunguis.
GENERAL DESCRnrIoN: A medium-sized box turtle (Table 2),
which tends to be round in shape (Figures 2A, 4A-D) except in the
northwestern part of its range (Figure 2, C; 4, E-H). In median
sagittal section, carolina has a gently rounded carapace (Figures
2B, D, 4). The posterior lobe of the plastron of males has a deep
concavity (Figure 4D, H) to harbor the carapace of the female during
copulation. The postorbital bar is narrow, cartilaginous, or absent;
toes number four on both hind feet of 131 out of 132 specimens on
which the toes were counted; axillary scale usually absent (Table 2);
1st central scute infrequently straight-sided (Table 2). The posterior
marginals have a large curvature radius, which means that the
marginals are relatively straight rather than flaring outwards (Figure
4, A-D). Some variation exists in both the presence of an axillary
scale and the flaring of the marginal, particularly in the north-
western part of the range. The plastral ratios of the various samples
of T. c. carolina are given in Table 2 (1-14).
The color pattern of T. c. carolina is one of the most distinctive
things about the subspecies, but unfortunately it also occurs in
major and similar patterns occasionally occur in bauri and triunguis.
The generic pattern of radiating lines that may be broken into a
series of spots is present in T. c. carolina and consists of light yellow
to orange or orange-rel lines or spots on ad k ground color. In
alm 3t every case the heli sflet Q impression that they
wer6 3iainted d -rand that the paint was smeared bIFore'it dried.
This produces broad lines or spots with poorly defined borders, and
at times lines run together to form broad blotches or configurations
(Figure 4). cmen fm
The largest T. c. carolina examined specimen from Michigan

A





34 BULLETIN FLORIDA STATE MUSEUM Vol. 14

with a carapace length of 167 mm. A specimen from Pennsylvania
and one from Indiana had lengths of 163 mm and 162 mm, respec-
tively. A specimen (AMNH 74468) from Massachusetts with a
length of 157 mm apparently had a life span of over 110 years. It
died in the New York Zoological Gardens in 1954 with two dates
carved in its shell, one for 1860 and the other for 1844. The average
carapace lengths of the various samples of T. c. carolina are given
in Table 2. The two most northern populations, Massachusetts
(2C) and Michigan (10C), have the highest averages, but the
samples show no definite north-south dine, and another northern
sample (11C, Cincinnati) has one of the lowest averages.
The two samples of T. c. carolina from the northwestern part of
the subspecies range (Table 1, 10C, and 11C; Figure 4 E-H) are so
different from the other samples of carolina that it was thought
during the early stages of the study that they might be very closely
related to T. c. major. The differences are that individuals from the
two northwestern populations are predominantly elongated in shape,
while most individuals from other populations are rounded; the
posterior marginals are flared rather than straight-sided in the north-
western specimens, and this flaring equals that of specimens of
major in some individuals; the frequency of an enlarged axillary
scale is greater in the two northwestern samples (especially in 10C)
than in most of the other samples; and in at least one of the north-
western samples (10C) the average size is larger than in most
samples. Compared with the degree and number of differences
separating the subspecies of Terrapene carolina, the differences that
separate the northwestern populations from the other populations
of T. c. carolina fall far short of the trinomial level, but use of the
tetranomial could be justified: Terrapene carolina carolina michigan-
ensis for populations 10C and 11C, and Terrapene carolina carolina
carolina for the other populations. On the basis of differences in
frequencies of occurrence of the enlarged axillary scale and differ-
ences in size, the southern population (11C) of T. c. c. michiganensis
could be further recognized as Terrapene carolina carolina michigan-
ensis ohioenat Further examinatiqps of populations 1PQ and 11C
could prabablitify the use ao the sext r prial (compare for
example, E, F, a nd *l Plate I). As previously noted, however, I
do not see that the application of Latin namnibeyond the trinomial
is very useful.
Two explanations arc readily available for the differences between
populations 10C and 11C and the other populations of T. c. carolina.

t~lswi~






MILSTEAD: BOX TURTLE EVOLUTION


First, in reference to the suggested relationship of the northwestern
populations to major, the characters of elongate body, flaring mar-
ginals, enlarged axillary scales, and large size are all characteristics
of putnami and may be relics of a pre-Wisconsin influence of putnami.
Second, the same characteristics are also associated to a lesser degree
with triunguis, and a triuguis influence may be the better explanation.
Populations 10C and 11C are not from the zone of intergradation
between carolina and triunguis.
VERTICAL DISTRnBUION: 1 have examined only four fossil speci-
mens of this subspecies. One, No. 1706 in the private collection of
Phillip Kinsey, from Aftonian deposits in the Haile XV A site,
Alachua County, Florida, is the oldest known representative of the
subspecies. Another, AMNH 1484, from "Pleistocene" deposits in
Talbot county, Maryland, is the holotype of Cope's (1869) Cistudo
eurypygia. The other two, ANSP 157 and 162, from Yarmouth
Interglacial deposits in Port Kennedy, Montgomery County, Mary-
land, were identified by Hay (1908) as Terrapene eurypygia. This
species was described as differing from T. carolina primarily on the
basis of what is now known to be an occasional scute aberration
in the posterior carapace of T. carolina, and I have considered T.
eurypygia a synonym of T. c. carolina (Milstead, 1965). Should
additional specimens demonstrate that this aberration was the rule
rather than the exception in early Pleistocene fossils related to T. c.
carolina, it may be necessary to reconsider the relationships between
the fossil and Recent specimens. If the high frequency of the
aberration in the fossils can be supported by other differences, it
may be desirable to recognize the early Pleistocene fossils as an
extinct subspecies, T. c. eurypygia, from which T. c. carolina evolved.
There is no need, to consider this possibility further at the present
time. Other records of Pleistocene fossils related to T. c. carolina
consist of one nearly complete carapace, two complete anterior
plastral lobes, three complete posterior plastral lobes, and numerous
carapacial and plastral fragment'fron .JI oian deposits near Cole-
man, Citrgs'lountm T'Floridi O aMMi ve identified as T. c. carolina
x putnami (Flteaf State Museum specimens). Auffenberg (158,
1959, 1967) notes that much of the material from Sangamon and
Wisconsin deposits in Florida displays an influence of carolina, but
I have been unable to see this; perBc because of a slightly
different interpretation of bauri. E







36 BULLETIN FLORIDA STATE MUSEUM Vol. 14

RECENT SPECIMENS EXAMNED. Uuless otherwise noted all samples are from
the Carolinian biotic province of Dice (1943).
1C. T. c. carolina. 15 specimens from the Long Island-New York City Area,
New York: AMNH 4596, 7029, 7033, 7748, 8791, 44661-4, 44668-9, 66561;
FMNH 92182; UF 3326; UCM 13798.

2C. T. c. carolina. Ecotone between Canadian and Carolinian biotic provinces
of Dice (1948). 10 specimens from Connecticut, Massachusetts, and Rhode
Island: AMNH 6406, 74468; BMNH 1889.9.18.1; UMMZ 99708-9, 113204-7,
S443.
3C. T. c. carolina. 58 specimens from New Jersey: AMNH 22552, 88010,
64657, 66095, 71290-2, 85541, 86552; ANSP 14, 17602, no number; KU 15883,
15886-8, 15890-1, 16383-94, 16401-3, 18344, 51458-9; RC 72, 1214, 2288,
2691, 3206-7, 8409; TNW 2284-8; UMMZ 72489, 74468-71.

4C. T. c. carolina. 21 specimens from Allegheny, Frederick, and Washington
counties, Maryland; Adams, Bedford, Cumberland, Huntingdon, and Perry
counties, Pennsylvania; and Jefferson and Morgan counties, West Virginia:
FMNH 83430; UF 12445-8; KU 3068, 48244-6, 48248; TNW 2021-2; UMMZ
74668, 99734-5, 113982-4, 113905, 113986-7.

5C. T. c. carolna. 45 specimens from Anne Anmdel, Baltimore, Calvert, Cecil,
Montgomery, Prince George's, and Queen Anne's counties, Maryland; and
Accomac, Essex, Fairfax, Mt Vernon, and Northhampton counties, Virginia:
AMNH 46009, 66180; BMNH 1963, 1034; FMNH 42441, 42443; UF 261,
1281, 9689(1), 9689(3), 10607 (1-8), 12348-50; KU 2747, 2850, 2854, 2870-1,
3069-72, 15828-9, 15889, 48240-3; NMS 1120; UMMZ 52870-3, 52875-8,
94181, 96613-4, 99736.
6C. T. c. carolina. 7 specimens from Ohio, Roane, and Tyler counties, West
Virginia: AMNH 69775; UMMZ 86032, 103001-5.
7C. T. c. carolina. 28 specimens from Floyd, Harlan, and Pike Counties
Kentucky; Watauga County, North Carolina; Carter, Claibore, Johnson, Sullivan,
and Unicol counties, Tennessee; and Washington and Wythe counties, Virginia:
AMNH 7584, 44590; FMNH 57445-6; UF 13155 (1-2); UF-RMJ 975,
976 (1-2), 977, 995-8; UMMZ 78978-81, 78988-4, 78986-9, 86225-6, 109555;
USNM 86673.
8C. T. c. carolina. 56 specimens from Blount, Campbell, Knox, Loudon, McMinn,
Meigs, Monroe, Polk, Rhea, Sevier, and Union counties, Tennessee: UF-RMJ
570, 591 (1-2), 592 (1-2), 600, 748 (1-8), 749 (1-2), 762, 789, 864,
90s (1-4), 9038 't ), 916 919, 923 (1-4), 924-5, 926 (1-2), 933, 934, .(-j),
985 (i,2), 936 (1-6lsJ jJ ~-; UMMZ 86732-3, 96601-2,.1027404,tSM
86668, 8606, 120111-2.

S9C. T. c. carolina. 24 specimens from Habersam and Lumpkin counties,
Georgia; Henderson, Macon, and Transylvania counties, North Carolina; and
Greenville and Oconee counties, South Carolina; AMNH 8429; UF 4226,
4438, 7535; UMMZ 72836, 86142-3, 96603-10, 96612, 97553-00.







MILSTEAD: BOX TURTLE EVOLUTION


10C. T. c. carolina. 39 specimens from LaPorte, Porter, and St. Joseph counties,
Indiana; Allegan, Barry, Berrien, Branch, Calhoun, Cass Hillsdale, Ingram,
Kalamazoo, Kent, Lake, Mecosta, Monroe, Muskegon, Ottawa, Van Buren, and
Washtenaw counties, Michigan; and Erie and Fulton counties, Ohio: UF
8268-9, 15447, 35430, 83393-5, 88403-4, 83442, 83444-5; UMMZ 32869,
34749, 36020, 40882-4, 52951, 53003, 53872, 54372-3, 70473-4, 70491, 72486,
74672-4, 78519, 81701, 83988, 86029-31, 99284, 103239, S1214.
11C. T. c. carolina. 19 specimens from Jefferson County, Indiana; Boone,
Carroll, Carter, Fayette, Grant, Greenup, Lawrence, Nichols, and Wolfe counties,
Kentucky; and Adams, Brown, Pike, and Scioto counties, Ohio: ANSP 311,
UMMZ 78976, 78992, 79135-6, 86033-4, 96600, 102738-9, 103414-7, 103420,
103422-3, 109554, 109888-91.
12C(T). T. c. carolina (with some influence of triunguis as evidenced by
coloration and shape of some specimens). 27 specimens from Coles County,
Illinois; and Clay, Parke, Richland, and Vigo counties, Indiana: FMNH 18047,
18190, 18642-9, 19192-, 22680, 31969-70, 39226-7; KU 46780-1, 46788-4,
46786-9; RMNH no number; SM 6166.
13C(T). T. c. carolina (with some influence of triungui as evidenced by
coloration, shape, and 3 hind toes of some individuals). Ecotone between
Austroriparian and Carolinian biotic provinces of Dice (1943). 7 specimens
from Lee, Montgomery, and Talladega counties, Alabama: UF 2377-80; UMMZ
89906, 92745, 99029.
14C(B) T. c. carolina (with some influence of bauri as evidenced by coloration,
shape, and 3 hind toes of some individuals). Austroriparian biotic province of
Dice (1943). 20 specimens from Burke, Candler, and Emanuel counties,
Georgia; and Anderson, Bamberg, Berkeley, Charleston, Colleton, Edgefield,
and Lexington counties, South Carolina: AMNH 69781; BMNH 1888.9.18.2;
UF 4406-8, 4413, 4415, 4433, 7907, 10181; UMMZ 72835, 81147, 86085,
89874-5, 103252-4, 108843, 115738.

Terrapene carolina putnami Hay
Figures 5, 8

Terrapene putnami Hay, 1906, Bull. Amer. Mus. Nat. Hist., 22:30.
Terrapene carolina putnami Auffenberg, 1958, Bull. Florida State Mus., 3 (2):
53-92.
Cistudo marnocki Cope, 1878, Proc. Amer. Phil. Soc., 17:229, part.
Terrapene canaliculata Hay, 1907, Bull. Amer. Mus. Nat. Hist., 23:850.
Trachemys nuchocarinata Hay, 1916, Florida State Geol. Surv., 8th ann. rept.:
39-76.
irapene antipex Hay, 1916, ibid. l -
^lb singleton Gilmorem,490fl0 ".S. Na nfus., 71 (15); 1-10.
TerrapenqJMi #% i 1958, Copeia (1): 33-- part.
Terrapene canaliculata Milstead, 1956, Copeia (3): 162-171, part.

Before describing T. c. putnami it is well to note that it is the
most poorly known box turtle. Whli the other subspecies A






BULLETIN FLORIDA STATE MUSEUM


T. carolina are represented by one or more good series of specimens,
we know putnami at present only from a few fragments of Pliocene
age, from isolated samples of a few specimens ranging rather con-
tinuously from Pliocene to Rancholabrean times, and from specimens
intermediate between putnami and other subspecies. Thus, when
a series of "pure" putnami is found, the characters of putnami may
differ in some ways from those given below.

RECONITION FEATumES: -large size (around 300 mm), length of
interhumeral seam equal to nearly one third of the total length of
the anterior lobe of the plastron, marginals greatly flared outwards
and upwards (Figure 5).

GENERAL DECRIPTION: largest of the box turtles. Some indi-
viduals attained a carapace length well in excess of 300 mm. The
interhumeral seam in putnami is the longest of ariy form in the
species except T. c. yucatana. In single specimens of putnami and
in series of intermediate forms, the interhumeral seam is 30% or
more of the length of the anterior lobe, and in individual specimens
reaches a maximum of 36%. The long interhumeral seam is associ-
ated with a short intergular seam (40% or less of the anterior lobe
length). The flaring of the marginals is the greatest found in the
species. Auffenberg (1958) gives the angle of flare from the per-
pendicular as 500 to 700 in putnami, and the average curvature radius
as 14.6 mm in putnami 15.8 mm in major, and 26.7 mm in baur.
The carapace of putnami is elongated and in median saggital section
is gently rounded, but with a hump on the 5th central scute caused
partially by the convexity of that scute and partially by the flaring
and guttering of the marginal scutes. The posterior lobe of the
plastron of males has a deep concavity to harbor the carapace of the
female during copulation. The postorbital bar is thought to have
been a broad, heavy span of bone (see Auffenberg, 1958, 1959, 1967);
an enlarged axillary scale is present in both putnami and inter-
mediate forms; and the 1st central scute is urn- or wedge-shaped in
all specimens examined. In a number of specimens, the flare of the
bony marginals tndin ej that the epidermal scutes must have been
greatly recurved to form a deep gutter around the posterior half of
the carapace. Anterior to the gutter, the 0w'T6f the marginals is
reduced to form a prominent lateral keel above the bridge.~Anteri-
orly to the bridge, the marginals again flare outwards to produce
a trace of guttering over the forelegs.


A


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


DIwrTr nIoN: The oldest specimens of T. c. putnami are from
the middle Pliocene of Florida in the southeast; the Illinoian of
Slaton, Texas, (near the Texas New Mexico border in the south-
west); and the Illinoian of Meade County, Kansas, in the midwest.
Thus at times in the early Pleistocene putnami ranged from peninsular
Florida west to New Mexico and north at least as far as Kansas. The
putnami influence in modern turtles may have extended even farther:
north to Michigan and south to Yucatan. The modern T. c. major is a
palmetto-pine forest inhabitant, and remains of other animals found
with putnami indicate that putnami occupied a similar habitat (Auf-
fenberg, 1958, 1959, 1967; Auffenberg and Milstead 1965; Dalquest,
1967; Milstead, 1967). It was probably not exactly the same as that
occupied today by major, because the early Pleistocene and modern
climates are not identical, but presumedly the habitat was sufficiently
similar to that of major to allow putnami to exist through the Pleisto-
cene and finally emerge in the Recent epoch as major. It is also pre-
sumed that this habitat was extensive and constant enough over the
eastern United States to permit putnami to range northwestward as
far as Kansas and New Mexico, and that changes in climate that pro-
duced changes in habitat were responsible for the evolution of triun-
guis from putnami west of the Mississippi River. The weakest point in
the story is the relationship of the early western box turtle remains.
The size of the specimens is the only thing that relates them to
putnami. No other characters are present. Thus, when more fossils
from both the midwest and the southeast become available, they
may show the presence of two subspecifically distinct giant box
turtles at the close of the Pliocene, one which gave rise to major
and one which gave rise to triunguis.
No late Pleistocene fossils of putnami have been found west of
the Mississippi River. All the fossils from that area are identifiable
as triunguis or as putnami xt triunguis. These are considered under
the discussions of triunguis.
SPECIMENS EXAMINED
Pliocene
SEarly Hemphillian: UF- 8P lgl ieral bone from deposits at the
McGeehee site, Alachua 4ity, Florida, tentatively identified aaWj. c.

Middle Hemphillian: several fragments in the UF from the Bone Valley
Gravel, Polk County, Florida.
Late Hemphillian: fragments of two or ire box turtles in the UF from
the Withlaoochee River south of Ocala. Florida. t" '
r-''
6






BULLETIN FLORIDA STATE MUSEUM


Pleistocene
Nebraskan: several fragments in the UF from the Santa Fe River north of
Gainesville, Florida.
Kansan: UF 11152, 11155-58, and others in the same series. Numerous
fragments from near Punta Gorda, Lee County, Florida.
Illinoian: MP 89442 and UT 882-815 from near Slaton, Lubbock County,
Texas (erroneously cited by Milstead, 1967, as Yarmouthian deposits),
and UMMP 48784 from Meade County, Kansas.
Sangamon and Wisconsin: all of the Florida specimens in the UF and
USNM collections listed by Auffenberg (1958, 1959, 1967). These include
the specimens from the Haile VIII A upper red zone (see discussion of
bauri below).

Terrapene carolina major (Agassiz)
Figures 5, 6, Table 2 (23)
Cistudo major Agassiz, 1857, Contrib. Nat. Hist. U.S., 1:445.
Terrapene caroina major Carr, 1940, Univ. Fla. Publ., 3 (1): '101.
RUoGNTmoN FETURES: Two or more of the plastral ratios of
T. c. major shown in Tables 1 and 2 distinguish it from each of the
other members of the species. The large body size separates major
from all living members of the species. The presence of four toes
on each hind foot further distinguishes it from bauri, mexicana,
and triunguis, and the concave plastron of males (Figure 6, D)
from mexicana, triunguis, and yucatana.
PRESENT DISTRBUTnON: northern ("panhandle") Florida west of
the Aucilla River (Figure 1). Intergradation is with bauri in the
western half of peninsular Florida; with triunguis in extreme north-
western Florida, southwestern Alabama, southern Mississippi, and
southern Louisiana; and jointly with carolina and triunguis in south-
western Georgia and southeastern Alabama. The intergrades are
considered in the discussions of bauri and triunguis.
GENEAL DESCIPnTON: largest of the living box turtles (Table
2, 23M), with some individuals exceeding 200 mm in carapace length.
The carapace is elongated and in median saggital section is either
rugose or gently rounded (Figures 2 G, 5, 6), but with a hump on the
5th cental scute ca~e 4 uy by the convexity of that scute and
partially by the flaring and guttering of the marginal scutes. The pot-
terior lobe of the plastron of males has a dee pS vity (Figure 6 D)
to harbor the carapace of the female during copulation. The post-
orbital bar is a broad, heavy span of bone, toes number four on both
hind feet on 9 of 4O specimens examined; enlarged axillary scale


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


it r-




FIh(FE 5. A, compuri'i` a M'3 p.,;al fragment ..1I Tcrr.pt~c v'.rinr p rnami
(UF 1616) with a carapace of a modem T. c. major (UMKC 0502).
Spots on the shells indicate points of comparison. Both specimens
are from Florida. B, skull of T. c. m.cor (UMKC 0502). C, skull
of T. c. mexicana (AMNH 7105-).4, skull of T. ornata longinsubw
"' (USNM 5983). E, skull of T. nisaoni nelsoni (UF 27138). "
,


C *'- '- r^






BULLETIN FLORIDA STATE MUSEUM


FIGUmE 6. Terrapene carolina major. A, living specimen, Bay County, Florida.
B, FMNH 83453, Leon County, Florida. C-E, FMNH 44990, Gulf
County Florida. F, FMNH 83454, Calhoun County, Florida.

present in all (59) specimens examined, 1st central scute urn- or
wedge-shaped in all the specimens exami T'iThe posterior mar-
ginals have a small radius, and are thus greatly flared outwards.
In many ca the marginal scutes are curved upwards to produce
a distinct gutter (Figure 6 C, E) around the posterior half of the


t"



B.


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


carapace. Anterior to the gutter, the flaring of the marginals is re-
duced to form a prominent lateral keel above the bridge. Anterior
to this lateral keel, the marginal again flare outward to produce a
trace of gutering over the forelegs. The plastral ratios of T. c. major
are given in Table 2 (23M).
T. c. major has no distinct color pattern of its own, but instead
has the color patterns of baur, carolina, and triunguis, and mixtures
of two or more of those patterns. Some adult specimens of major
have a white or white-blotched head. This is also true of yucatana
and in occasional specimens of mexicana, T. c. bauri x major and
T. c. major x triunguis. The speckled head of coahuila is close to the
white-blotching. All three of the forms major, yucatana, and coahuila
are presumed cose relatives of putnami, and I have suggested
(Milstead, 1967) that the white markings may have been a putnami
characteristic. Another color character of putnami may be the "fire-
marked" examples of major, mexicana, and yucatana. All three sub-
species live in areas subject to fire, usually by the deliberate burning
of the habitat by man. Many specimens have fire scars on the
scutes, and a number of these turtles have a color pattern of yellowish
horn invaded to varying degrees by melanistic blotches. This color
pattern has been generally attributed to fire, but I am not fully
convinced of it. Some specimens that have the color have no other
signs by fire, while others with fire scars on the scutes lack the color.
Although my data are far from adequate, I have the impression that
the "fire-marked" pattern may start, in young turtles having the
proper genetic alleles, as horn or straw-colored scutes with dark
borders and that the melanin increases with age. If this is so, the
variation is considerable, because some specimens retain the light-
colored scutes with dark borders throughout life, while others become
partly to completely melanistic.
VnmxcAL DirsrmunoN: As noted previously I interpret major
as being a modified putnami extended into Recent times. This is
essentially the interpretation first proposed by Auffenberg (1958).
For the present epoch at least, this interpretati. provides an abso-
lute means of identification: if a turtle in question is fossil, it is
either putnm tor pu nati xt major; if it is not fossil, it is ri016r.
The distinction between putnami and putnami xt mpjor is, as noted
above, a question that cannot be resolved _W the basis of present
material.
The range of putnami must have been greatly modified af e-






BULLETIN FLORIDA STATE MUSEUM


modified by the changing conditions of the Pleistocene; During each
glacial stage putnami moved southward in the midwest because of
cooler temperatures, westward across Texas because of additional
territory made available by increasing humidity, and seaward around
the Gulf Coast to take advantage of the coastal plain exposed by
lower sea levels. Reversals in these movements took place with
reversed physical conditions during the interglacial periods. Following
the Wisconsin glaciation, rising sea levels and increasing aridity to
the west gradually restricted puinami to the present range of major.
The factors that caused the retreat of putnami also permitted the
range extensions of bauri northwestward and triunguis eastward. Any
relict populations left by putnami in suitable areas were swamped
by the two advancing subspecies, and eventually the influences of
bauri and triunguis, and also of carolina, modified the characters
of putnami into those of major. If the climatic and biological factors
that caused the extirpation of putnami continue in the same direc-
tions, it may be prophesied that major will be swamped at some
future time leaving only three-way intergrade populations of bauri,
carolina, and tringuas.
If the description of major is compared with that of putnami, it
will be found that most of the characters of major are those of
putnami, and that a number of them are unchanged (e.g., axillary
scale and shape). The influence of bauri, carolina, and triunguis on
the characters of putnami has produced in major: smaller size (300
mm to 200 mm), increased curvature radius of marginals (14.6 mm
to 15.8 mm), increased intergular seam ratio (38% to 45%), de-
creased interhumeral seam ratio (30% to 29%), decreased interpec-
toral seam ratio (30% to 26%), possibly an increase in the length
of the anterior lobe in relation to the length of the posterior lobe
(? to 66%), and the expression of the color patterns of bauri, caro-
lina, and triunguis. All the quantitative differences may become more
emphasized when a series of "pure" putnami becomes available.

SPncnaMrs tk* alr
23. M. T. c. maor. troriparian biotic province of Dice (ti): 59 speci-
mens from Calhoun, Franklin, GAugLJen4tlhAert y, and Walsulla counties, Flor-
a.. ida. Most of the specimens irintrs sample have been cited previously (Milstead,
"1967, population H). The only additions to the sample were two untagged
specimens at Florida State University and one specimen (1903.8.25.3) in the
British Museum. ,


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


Terrapene carolina bauri Taylor
Figures 7, 8, Table 2 (16B, 17B)
Terrapene baurt Taylor, 1895. Proc. U.S. Nat. Mus., 17:576.
Terrapene carolina bauri Carr, 1940, Univ. Fla. Publ., 3 (1):100.
Terrapene innoxia Hay, 1916, Florida State Geol. Surv., 8th ann. rept. :39-76.
RECoGNrToN FEATUBES: Two or more of the plastral ratios
of T. C. bauri shown in Tables 1 and 2 (16B and 17B) distinguish
it from each of the other members of the species. The shape of
bauri in lateral view (Figure 2 F) also separates it from all other
members of the species. The presence of three toes on each hind
foot further distinguishes it from carolina, major, and yucatana, the
concave plastron of males (Figure 7 D) from mexicana, triunguis,
and yucatana; and its small size from major, putnami, mexicana, and
yucatana.
PRESENT DiSTRIBUroN: eastern half of peninsular Florida (Fig-
ure 1). Intergradation (discussed below) occurs with carolina in
eastern Georgia and northeastern Florida, and with major in the
western half of the Florida peninsula.
GENERAL DESCRIPION: a small to medium-sized box turtle
(Table 2) elongate in shape, and with a highly vaulted carapace
posteriorly. In median saggital section the highest point of the
carapace is seen on the posterior part of the third central scute
(Figures 2 F; 7). The greatest width of the carapace also occurs
at the third central (Figure 7 D). The greatest height and the
greatest width occurring together well behind both the bridge and
the mid-point of the carapace give an overall impression of a turtle
with its bulk badly skewed to the rear. This is the most noticeable
feature of the subspecies. Occasionally a hump appears on the 5th
central scute (Figure 7 A, F) as in major (Figure 2 G). The
posterior lobe of the plastron of males has a deep concavity (Figure
7, D) to harbor the carapace of the female during copulation. The
postorbital bar is narrow, cartilaginous, or absent; toes number 3
on both hind feet of 10 out of 12 s which, zne toes were
counted; ,illary sc4e u Table 2, lo3 and 17B); 1st
central sW ,:-infrreentl? raight-sided: Auffenberg (1958, 190)
has considered a straight-sided 1st central scute to be a characteristic
of bauri, but this is due to a slightly different interpretation of the
subspecies. As it emerges from this study, bauri is much more re-
-4tricted in range than previously thought, and I interpret most of
^ ^


1969





BULLETIN FLORIDA STATE MUSEUM


Auffenberg's bauri as actually being bauri x major. Thus, the straight-
sided 1st central becomes a character of bauri intergrades, particular-
ly intergrades with major (Table 2, cf. bauri populations 16 and 17
with intergrade populations 15 and 18-22). The posterior marginals
are more flared than in carolina and have developed to some extent
the recurving or guttering of the greatly flared marginals of major
(Figure 7). At times there may be a lateral keel above the bridge.


6a L


FIGURE 7.


I


B


Terrapene carolina baurA, living specimn, Dade CounqtyFlorida.
B, AMNH 8044, Brevard County, Florida.. C-D, FMNH 83450,
Dade County, Florida. E-F, KU 20506 and 20516, Indian River
County, M&4


Vol. 14


*4%-






MILSTEAD: BOX TURTLE EVOLUTION


The color pattern of T. c. bauri is another distinctive feature of
the subspecies, but as in carolina, it cannot be relied upon. Some
specimens of major and almost all of the bauri intergrades have the
pattern, and very similar patterns occur infrequently in carolina and
triunguis. The T. c. bauri pattern consists of long, thin, radiating,
light (cream to yellow) lines on a dark (olive-drab to grayish or
brownish black) ground color (Figure 7). The lines usually, but
not always, have distinct borders and are rarely broken into spots.
VERTICAL DISTRIBUTION AND INTEBCRADATION: Auffenberg (1958,
1959, 1967) has advanced the thesis that T. c. bauri evolved from
carolina-putnami intergrades that became isolated sometime in the
Pleistocene. An alternative would be to consider bauri a third sub-
species already existing in the Florida peninsula at the beginning of
the Pleistocene. The only evidence to support the hypothesis of a
third subspecies are a few morphological features of bauri not found
in carolina or putnami, and differences in behavior patterns (L.T.
Evans, pers. comm.). All of these can be attributed to the isolation
necessary in Auffenberg's intergradation thesis, however, and Auffen-
berg's thesis also avoids the problem of defining the geographic
range of a pre-Pleistocene bauri. As I understand it, sea levels at
the end of the Pliocene were higher than they have been since, and
most of Florida spent the Pliocene under water. The Florida penin-
sula first emerged during the Nebraskan glacial stage, was inun-
dated again during the Aftonian interglacial, emerged again during
the Kansan glacial, and was inudated for the last time during the
Yarmouthian interglacial. Sangamon sea levels are presumed to have
been only slightly higher than they are at present.
In Auffenberg's thesis, both T. c. carolina and T. c. putnami
reached Florida about the same time and intergraded much as bauri,
carolina and major do today. Rising sea levels following the first or
second glacial stage isolated a population of these intergrades on one
or more islands where the Florida peninsula is today. The bauri
characteristics began to develop during this isolation. Lowering sea
levels at a later date reunited the isl ~ it the mainland and
brought "baur" into cont16m mi and then with caro-
lina. The order b&t ll ase#d on the reasoning that putnami
occupied coastal marshes on the mainland, carolina occupied upland
forests to the north, coastal marshes were the first box turtle habitats
to move onto the emerging zone between the mainland and the old
land, and the upland forest habitat (and carolina) did not appear
-^^^







BULLETIN FLORIDA STATE MUSEUM


until much later. The rising of the sea following the maximum extent
of the glacier again brought the coastal marshes and putnami into
contact with "bauri". Following this, there may have been a second
isolation of "bauri" that brought a greater refining of the bauri charac-
teristics. At present, we have no information on whether there were
one or two isolations, but by the end of the Sangamon interglacial
(approximate age of Haile VIII A), the characteristics of bauri had
developed to the point that fossils from that time can be identified as
T. c. bauri with only minor reservations (see below).
The modern bauri appears to be a mixture of carolina, putnami,
and new (bauri) characteristics, and can be analyzed accordingly:
carolina characteristics: small size, lack of axillary scale, reduced post-
orbital bar.
putnami characteristics: elongate shape, flaring marginals.
bauri characteristics: "humping" of the shell, narrow skull, three toes on
hind feet (number of toes in putnami unknown), plastral ratios inter-
mediate between those of carolina and putnami, and straight-sided first
central scute (although this is now gone from living bauri, it persists
in intergrades with carpldn and major).
The influence of carolina on the evolution of bauri was probably
very slight after the initial intergradation with putnami and the first
isolation. The influence of putnami, on the other hand, must have
been much more significant because of the more frequent contact
between putnami and bauri.
We have very little fossil evidence for the evolution of Florida
box turtles during the first half of the Pleistocene. Like putnami and
carolina, bauri first appears in the fossil record fully developed with
no real clue to its origin. The pre-Rancholabrean fossils from Florida
consist of one specimen of carolina and several specimens of putnami.
An Illinoian site in Citrus County has yielded intergrades between
putnami and carolina with no apparent traces of bauri characteris-
tics. The lack of bauri evidence in these fossils, and the fact that
bauri appeared fully developed in the next interglacial stage, seem
to question Auffenbcrg's thesis on the origin of bauri. It should be
noted, though, that Citrus County -is located in the northern '- if
of there coIast~jFgPi da, and the turtles found therep-rittdlyof
have been in contact with bauri-like turtles. That bauri was de elop-
ing in southeastern Floriwdalrtrfg iTfnoian*PAfes as the result of
an earlier intergradation between putnami and carolina does not
exclude the possibility that carolina and putnami could continue to
intergrade elsewhere independently of bauri.


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


Nothing presented in the preceding four paragraphs really elim-
inates the possibility that bauri was a third subspecies existing on an
island in the Gulf of Mexico prior to the beginning of the Pliocene.
It is hoped that fossil material that will provide a solution to the
problem will be found eventually.
Most of the fossil finds from Rancholabrean deposits in Florida
have consisted of one or a few specimens and are useful only in a
limited way, with two notable exceptions: a large series of fossils
from the Reddick IB site, Marion County, Florida (Auffenbcrg, 1958,
1959), which lend themselves to statistical analyses; and a smaller
series of fossils continuous through three zones of deposition at the
Haile VIII A site, Alachua County, Florida (Auffenberg, 1967).
The Reddick IB specimens originally presumed to be of Illinoian
age (Auffenberg 1958, 1959), but now thought to be of Sangamon
age (Auffenberg, 1967), are of turtles intermediate between putnami
and bauri. In general the shape of the turtles is like that of putnami,
but with a distinct skewing of the bulk posteriorly as in bauri. The
intergular and interhumeral seam ratios are like those of putnami,
and the carapace length is intermediate (Table 4, 85PB). Auffenberg
(1958) gives the curvature radius of the marginals as intermediate
(23.6mm) and notes that the axillary scale and first central scute are
variable. The single skull found at the site is also considered inter-
mediate (Auffenbcrg, 1959). At present I identify the Reddick IB
specimens as horizontal intergrades, T. c. putnami x bauri. The ob-
vious putnami characters in the Reddick IB turtles do not, however,
demand the presence of putnami. The environment, presumed to have
been a hibernaculum in a near-putnami-type habitat, may have been
selecting for putnami traits in T. c. bauri. Should this prove to be the
case, the specimens should be designated T. c. bauri xt putnami.
The earliest record of bauri was found in Sangamon deposits at
Haile VIII A in Alachua County, Florida. The site is of further inter-
est in that it shows intergradation and replacement of bauri by put-
nami through successive stages of deposition. Auffenberg (1967) de-
scribes the site as an old sinkhole with four distinct zones of de-
p.'c;i'p above the rubble of the. old l f. Turtle remains have
been ,fplnd in the top threeF 8 .elo ermost of these, the sand
zone, contains ipntimens That are almost identical to the modern
T. c. bauri, the uppermost (upper red clay) zone contains specimens
almost identical to putnami, and the middle (lower red clay) layer
contains specimens of intermediate forms. Too few specimens are
available for a statistical analysis of any of the characters, but by the


4-


- -






50 BULLETIN FLORIDA STATE MUSEUM Vol. 14







A- _. *_ .4


C


FIGURE 8. Fossils from Haile VIII A, Alachua County, Florida. A-B, Terrapene
carolina bauri (with a T. c. putnami influence) UF 3136, Sand Zone.
C-D, T. c. putnami x bauri, UF 3150, lower red zone. E-F, T. c.
putnami (with a T. c bauri influence), UF 3130, upper red zone.
Courtesy of Florida State Museum.
size and shape of the carapaces and the degree of flare of the margi-
nals, I tentatively identify the turtles as: sand zone, T. c. bauri with
some influences putnami: upper red zone, T. c. putnami with some
influe~ae of bauir;ad lower red zone, T. i:g.auri x putnami. Ex-
amples of all three T iS are shown in Figure 8. Auffenberg inter-
prets the sequence of eve jL ghtly- I tlI4' as a bauri habitat
changing to a putnami habitat through the influence i krising sea
levels prior to the Sangamon maximum. At the time the sand zone
was deposited, the area was a bauri-type habitat occupied by bauri.


~I
Tta.






MILSTEAD: BOX TURTLE EVOLUTION


At the time the lower red zone was deposited, the habitat had
changed to an ecotone between bauri and putnami habitats and had
brought putnami in to intergrate with bauri. By the time the upper
red zone was deposited, the habitat had changed to a putnami type,
and bauri had retreated to higher ground, leaving the area to put-
nami. Auffenberg has long contended that putnami and bauri peri-
odically replaced each other as habitats changed with rising and
falling sea levels throughout the Pleistocene, and this idea is the
basis for the suggested evolution of bauri given above. Other se-
quences of succession, both putnami to bauri and vice versa, have
been given by Auffenberg (1958, 1967) for other fossil specimens
from Sangamon and Wisconsin deposits in Florida. None of these is
as good as the Haile VIII A example because the sequences are not
complete and the ages of the deposits are not fully correlated.
Before leaving the Haile VIII A specimens, it should be pointed
out, as it was for the Reddick IB specimens, that the presence of
putnami is not mandatory. The change from bauri to putnami could
have taken place through selection of putnami characteristics in the
gene pool of baud. In this case, the lower-red-zone intermediates
should be designated T. c. bauri xt putnami.
PRESENT INTERGRADATION: Sample 15CB represents an intergrade
population between T. c. carolina and T. c. bauri. Some specimens in
the sample have the color pattern of carolina, some have the pattern
of baur, some have an intermediate pattern, and two specimens have
patterns similar to triunguis. Shapes in the sample are carolina-like,
bauri-like, or intermediate. The intergular and interhumeral seam
ratios (Table 2) are intermediate. In 15 specimens 11 have three
toes on each hind foot, and 4 have four toes. A straight-sided 1st
central scute is more frequently present in the intergrade population
than it is in either carolina or bauri (Table 2).
Samples 18BM-22BM represent intergrade populations between
T. c. bauri and T. c. major (Figure 9 A-C, Table 2). All specimens
in all these samples have the coloration of bauri. Sample 21BM has
a shape intermediate between bau r ja ajor; samples 18BM and
21BM have intermnediat"it are closer to bauri. Some
specimens in each-samnflhave three toes on each hind foot, whilr :
others have four. Occasional specimens have three toes on one foot
and four on the other. In Sample 21BM the number of specimens
with three toes and the number with four ties are about equal, but
three toes predominates (greater than 70%) in all of the other






BULLETIN FLORIDA STATE MUSEUM


E ... .
-r "'


F .


FricuR 9. Some Recent Terrapene carolina intergrades. A-B, T. c. hauri x
major, UF 8619, Big Pine Key, Monroe County, Florida. C, T. c.
bauri x major, UF 972, Alachua County, Florida. D, T. c. carolina
x major x triunguis, UF 4444, Bibb County, Georgia. E, T. c. caro-
lina x major x triunguis, AMNH 29883, Thomas County, Georgia. F,
T. c. carolina x triunguis, FMNH 83417, Crawford County, Indiana.

samples. The ratio between the anterior and posterior lobes (Table
2) is like major in sample 20BM, and like bauri in the other samples.
The intergulax txio (Table 2) is intermediate between bauri and
major ih 4 mpleAB M, like bcuri in 21BM, and like putnami .(as
now known) in 18Bi940BM, and 22BM. In samples 18BM, 19BM,
and 21BM, an enlarged axillary caie, is mogp equently present
than in bauri (Table 2). A straight-sided 1st central scute is more
frequently present in all of the intergrade samples than it is in
either bauri or mafor (Table 2).
e


B


Vol. 14







MILSTEAD: BOX TURTLE EVOLUTION


RECENT SPECIMENs EXAMINED. All are from the Austroriparian biotic
province of Dice (1943).
15CB. T. c. carolina x bauri. 16 specimens from Atkinson, Charlton, and Ware
Counties, Georgia, and Bradford, Clay, Duval, Flagler, Nassau, and St. John's
counties, Florida: UF 4432, 7537, 9704, 9881-2, 10945, 12012, 14666-7,
14672, 41638, 47912; UCM 2193; UMMZ 67811, 81145, 106327.
16B. T. c. baur. 27 specimens from Brevard, Indian River, Orange, and Osceola
counties, Florida: AMNH 5928-30, 8044-5, 66094, 66107; UF 6822, 9000,
47143; KU 17367, 18348, 19738-9, 19741, 20506, 20508-18.
17B. T. c. bauri. 18 specimens from Dade, Martin, and Palm Beach counties,
Florida: FMNH 83449-50; UF 390, 390 (A-E), 6604, 9575; KU 46814,
46827; TCW 8984; UMMZ 53231-2, 53294, 110682-3.
18BM. T. c. bauid major. 11 specimens from Monroe County, Florida,
mostly from the keys: UF 7101-3, 8619-20; MCZ 7393, 26768-9; UMMZ
107223-4, 111425.
19BM. T. c. bauri x major. 9 specimens from Charlotte, DeSoto, Glades,
Highlands, Lee, and Sarasota counties, Florida: AMNH 65828; BMNH 1957.-
1.5.76, 1957.1.5.78; FMNH 83448; UF 586, 921, 4164, 8617, 11121.
20BM. T. c bauri x major. 12 specimens from Hillsborough and Pinellas
Counties, Florida: BMNH 1897.10.15.1-3; UF 6514-5; KU 48249; UMMZ
61738-42; and one unnumbered specimen at Florida State University.
21BM. T. c. bauri x major. There may be an influence of T. c. carolina in
this sample. 36 specimens from Alachua and Marion counties, Florida: AMNH
8284-6; ANSP 21524; UF no number A-D, 537, 965, T972, 3328, 5210-11,
6512-13, 14117, 14266, 38050, 44264, 45400; KU 46811-13, 46815, 46817-18,
46820-1, 6824-6, 46828-30; UMMZ 52475.
22BM. T. c. bauri x major. There may be an influence of T. c. carolina in
this sample. 7 specimens from Citrus, Dixie, Lafayette, and Levy counties,
Florida; UF 7449, 9657, 11122, 14128, 14669; KU 46823, 46826.

Fossm SPEcsINs EXAMINED
85PB. T. c. putnami x bauri. 31 specimens of Sangamon Interglacial age from
the Reddick IB site, Alachua County, Florida. The specimens examined con-
sisted of 2 complete carapaces and fragments of others, 20 anterior plastral
lobes, and 16 posterior plastral lobes. The average carapace length for this
sample given in Table 4 (154 mm) is a repetition of Auffenberg's (1958)
figure rather than an average of the lengths .Lthe two carapaces seen (142 and
168 mm). The anterior lob ratio 4 |klastral lobe/posterior plastral
lobe) given in Table 4 is ba j&4gplete plastra found intact. The other
plastral ratios are base on N=20 for the anterior lobe and N=16 for the-" "
posterior lobe. The specimens include: UF 1462-8, 1476, 2060, 2060 A-C,
2061, 2063, 2179, 2333, 2339, 2913, 2915, 4266, 4747, 5697, 5699-700, 6101,
6137, 6600, 7041 A-E, 7041 G-I, 9972. Other speelmens include those from
the Haile VIII A site and all UF and USNM specimens from Sangamon
knd Wisconsin deposits of Florida cited by Auffenberg (1958, 1959, 1967).







BULLETIN FLORIDA STATE MUSEUM


FunRE 10. Terrapene carolina triunguis. A-C, living specimen, Bryan County,
Oklahoma. D, UT 7456, Byran County, Oklahoma. E, UT 6539,
Jefferson County, Texas. F, UT 8838, Angelina County, Texas. G,
UT 88 Robertson Cuunty, Texas. H, living specimen, Morgan
County, ~Mlouri, I, KU 23351, Cherokee County, Kansas.

Terrapene carolina triunguis (Agassiz)
Figures 10-11, Table 2 (31-44)
Cistudo trfnguis Agassiz, 1857, Contrib. Nat. Hist. U.S., 1:445.
Terrapene carolina trfl uts Strecker, 1910, Proc. Biol. Soc. Wash., 23:121.
Cistudo marnocki Cope, 1#88, Eroc. Am. Phil. Soc., 17:229, part.


.r .


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


Terrapene whitneyi Hay, 1916, Bull. Univ. Texas, 71:1-24.
Terrapene bulverda Hay, 1921, Proc. U.S. Natl. Mus.. 58:83-146.
Terrapene impress Hay, 1924, Publ. Carnegie Instit. Wash., (322A):245.
Terrapene lanensis Oelrich, 1953, Copela, (1):33-8, part.
Terrapene canaliculata Milstead, 1956, Copeia, (3):162-171, part.

RECOGNTION FEATURE: One or more of the plastral ratios of
T. c. triunguis shown in Tables 1 and 2 distinguish it from each of
the other members of the species. The shape of triunguis in lateral
view (Figure 2H) separates it from all members of the species
except mexicana and yucatana, and the shape in cross-section through
the posterior part of the 4th central from mexicana and yucatana
(Figure 2H, I, J). The presence of three toes on each hind foot
further distinguishes triunguis from carolina, major and yucatana;
the smooth or only slightly concave plastron of males from bauri,
carolina, major, and putnami; and the small size from major, mex-
icana, putnami, and yucatana. Jackson and Legendre (1967) have
shown a higher level of blood serum cholesterol in major than in
triunguis, but additional studies are needed to determine the use-
fulness of this observation as a taxonomic character. The number
of specimens they examined was very small, and there is some
evidence that the differences may be dietary rather than hereditary.
The carnivorous species they studied, for example, had higher choles-
terol levels than the vegetarian or omnivorous species. Thus, the
higher cholesterol level of major may be due simply to a higher
percentage of animal foods in its diet.
PREsmNT DISTRIBUTION: West of the Mississippi River from cen-
tral and southeast Texas northward into Wisconsin (Figure 1).
Intergradation (discussed below) is with carolina along the Miss-
issippi River roughly from central Mississippi northward to the Ohio
River; with major along the Gulf coast from central Louisiana to
Florida; and simultaneously with carolina and major in southeastern
Alabama and southwestern Georgia.
GENERAL DESCRIPTION: the smallest of the carolina box turtles
in the southwestern part of its range.*ut increasing in size north-
eastward to attain the size- of Fta and bauri (Table 2). The
^rItj jelonpgatsied, lgyd vaulted, both anteriorly and poste-
riorly, aid ivith the 3rd central scute elevated to form a small hump
(Figures 2H, I; 10A, H). The plastron of males is smooth or has
only a shallow concavity in the posterior lob (Figure 10C, cf. 4D).
The postorbital bar is narrow, cartilaginous, or absent. Of 101






BULLETIN FLORIDA STATE MUSEUM


specimens on which the toes were counted, 94 had three toes on
each hind foot, 3 had four toes, and 4 had three toes on one hind
foot and four on the other. The presence of an enlarged axillary
scale is variable. In some samples the frequency of occurrence of
the enlarged axillary scale approaches that of T. c. major (e.g. Table
2, 36T-38T), but in most samples the frequency is intermediate
between T. c. major and T. c. carolina. The first central scute is
also variable, but is generally something other than straight-sided
(Table 2). The posterior marginal scutes are similar to T. c. bauri
in their degree of flaring (i.e., intermediate between carolina and
major). A lateral keel above the bridge may be present. The plastral
ratios of T. c. triunguis are given in Table 2 (31-44).
The coloration of T. c. triunguis is highly variable, but three
types of pattern predominate throughout the geographic range. The
generic pattern of radiating light lines is present in many individuals,
although the lines may be broken into series of dashes or dots
(Figure 10A, B, D-G). Frequently each light line is bordered by
a dark line (Figure 10E, F), and in occasional individuals the light
lines may be faint or lacking altogether. The latter situation results
in a color pattern of radiating dark lines. This type of pattern is
of more frequent occurrence in mexicana than in triunguis. The
ground color of triunguis in both light-and-dark striped individuals
is straw color to horn color, most frequently the latter. The third
type of predominant color pattern in triunguis is the loss of both
light and dark stripes to produce a turtle that is a uniform horn
color (Figure 10H, I). The color pattern in triunguis appears to be
genetically based and dependent upon several pairs of factors. Some
turtles of all ages including yearlings have the uniform coloration,
others of all ages have the lines, and still others have varying degrees
of light lines, dark lines, and uniform coloration intermixed (Figure
10A, B).
The reduced concavity in the posterior lobe of the plastron in
males of T. c. triunguis and the development of the hump on the
3rd central scute of the carapace are interesting in that they may
provide an example of "complementarity of structure and function"
as ilated to behavior. In observed matings of box turtles, a male
of T. carolina carolina, T. caroliia major, or T. coahuila mounts the. -
female with the posterior pamtof her shelMlFtting into, the con-
cavity in his plastron, while in T. carolina triunguis the male has
his main shell axis reclined away from the female and lies .on th
posterior part of his carapace supported by the hump on the third
wt Lmtiwc tk


Vol. 14







MILSTEAD: BOX TURTLE EVOLUTION


central scute. Legler (1960) in discussing mating in T. ornata ornata,
which lacks both a plastral concavity and a carapacial hump, has
noted that the male angles backwards away from the female sup-
ported by his hind legs, and that the stress on the legs is so great
that the male may be incapable of walking following copulation.
Auffenberg (pers. cor.) has observed similar behavior in T. c. bauri
and T. c. major.
Other noteworthy features of triunguis are the differences be-
tween the samples from the southern part of the range and those
from the northern part. Although it does not form a consistent
dine, an overall increase in size and bulk extends from Texas to
Missouri. The carapace lengths that reflect these increases are shown
in Table 2, but it should be noted that the increases are not di-
rectly proportionate to carapace length. The turtles from Missouri
are much more massive and as a result are slightly differently shaped
than turtles from central Texas (Figure 10, cf. A-G with H-I). The
interhumeral seam ratios (Table 2) also show an inconsistent in-
crease from south to north. Thus, as was the case in T. c. carolina,
the turtles of one part of the range can be distinguished from those
of another part of the range; but unlike T. c. carolina, the differences
in T. c. triunguis can be related to the biotic provinces of Dice
(1943). Nomenclatural recognition of the differences might be in
order, but as in the case of T. c. carolina, I do not feel that the
differences warrant recognition at the subspecific level. This again
raises the question of the use of the tetranomial: Terrapene carolina
triunguis triunguis for turtles from the Austrotiparian and Texan
biotic provinces (Table 2, 30-37 and 39), and T. c. triunguis kansensis
for turtles from the Carolinian and Illinoian provinces (Table 2,
38 and 40-44). For reasons previously given this is not proposed.
The differences between the samples of T. c. carolina from the
northwestern part of its range, compared with these from the rest
of the range were attributed to the possible influence of triunguis
or putnami. In like manner the different morphology of triunguis
in the northern part of its range may be attributed to the influence
of carolina or of putnami, but the different in size niMrit further
consideration. Despite Lindsey's (1966) conclusion that nonmarine
turtles show, t a i idinal trend in size, both T. c. carolina andT. c.
triunguis reach their greatest size in the northern parts of their range.
This may be a lingering influence of putnan&lbut even so, it would
have to be maintained by selection, and the end result is that both
subspecies exhibit Bergman's rule for homoiothermic animals. Tinkle
-*i






BULLETIN FLORIDA STATE MUSEUM


(1961) has found similar north-south size relationships in Sterno-
thaerus.
From these and other examples and from the simple experiment
of placing turtles of different sizes in a refrigerator, it seems advan-
tageous for a turtle to be large in the colder part of its range. But,
if this is so, why did triunguis in the north become reduced in size
from putnami by nearly two thirds, while major in the south became
reduced by only one third? Apparently, a turtle must be large
enough to survive winter cold, but small enough to recover rapidly
in the spring and on warm days during the winter. The giant
putnami developed in pre-Quaterary times under a warm maritime
climate that had no extremes of cold or heat such as those found
in the continental climates of today. Under those pre-Quaternary
conditions, it might have been advantageous for a turtle to be large,
because it would respond slowly to temperature changes between
day and night, and this would produce a relatively constant body
temperature for efficient metabolism.
In developing from putnami, triunguis had to reduce its body
size to utilize heat better for recovery following modem winters.
The average carapace length of triunguis is 127 mm in western
Missouri and eastern Kansas, and 116-117 mm in southwestri Louisi-
ana and southeastern Texas. Winters in the northern area are severe
with few warm days, and spring does not come until late April,
while winters in the southern area are mild with frequent periods
of warm days, and spring comes in late February or early March.
I consider the larger size of the northern turtles to be advantageous
for survival in the northern winters, while the smaller size of the
southern turtles is advantageous for rapid recovery from cold in
order to utilize the warm winter and early spring days.
The large size of major, which occupies a more southern and
warmer area than triunguis in southern Texas and Louisiana, is the
stumbling block in the theory: major should be smaller than tri-
unguis. However major is a direct descendent of putnami, occupies
the last putnami-type habitat available, and probably was not sub-
jected at an.-% e during the Pleistocene to such rigorous climatic
changes as influenf sv1olution of the box turtles in the midwest.
The relatively large sizes of mexicana and yucatana support this
argument in that they are lsely related--to both triunguis and
putnami and are distributed to the south of triunguis. The reduction
in size from putapi to major was attributed earlier (see discaSef lb
of T. c. major) to the influence of smaller subspecies, but may be
ev


Vol. 14







MILSTEAD: BOX TURTLE EVOLUTION


due to selection for smaller size in response to the cooler modern
climates and the need to recover following cold days.
A crude attempt to test some of the theories presented in the
preceding paragraph was undertaken in the winters of 1962-63 and
1965-66. A dozen box turtles ranging in size from 80 mm to 180 mm
carapace length were kept in an outside pen at the University of
Missouri-Kansas City. The nine smallest turtles were Terrapene
carolina triunguis and Terrapene ornata ornata from the Kansas City
area, and the three largest ones were Terrapene carolina major from
Bay County, Florida. In both tests the turtles were introduced into
the pen during the fall and provided with food and water, and with
piles of leaves to serve as shelters in the fall and hibernacula in the
winter. At the outset it was predicted that (1) the Florida turtles
would survive in spite of the severe winters because of their large
size; (2) if any turtles should die, they would be the smaller, local
turtles; and (3) the first turtles to appear in the spring or on warm
days in winter would be the smaller, local turtles.
The first test in 1962-63 was something of a failure because of
an unforeseen circumstance. The winter was severe and no turtles
were seen on the surface after the middle of November. When no
turtles had appeared on the surface by mid-May, the leaves were
removed. All of the turtles were not only alive, but also active and
fat, presumably from feeding on a rich aggregation of earthworms
that had accumulated under the leaves. Apparently the turtles had
not appeared on the surface because they had no physiological
reason to do so.
The 1965-66 test produced better results. The winter was unusually
mild with many warm, sunny days. On most of the warm days the
smaller turtles, including the smallest major with a carapace length
of 141 mm, appeared on the surface, but the two largest turtles
were not seen until spring. With the onset of the first cold weather,
all of the turtles maintained a body temperature (measured by a
Yellow Springs Instrument Co. telethermometer through thermistor
probes in the turtles' coeloms) several degrees higher than the
environmental temperature, (@easured nthermistor probes taped to
the turtles' caraRgL surfaces) ac 'over a week. On two occasions
measuitfents were taken through sequences of a cold day (0 C or
below) one or two cool days, two or three warm days, a cool day,
etc. In both cases the smaller turtles showed increases in body
temperatures and became active on the -warm days, while the two
largest turtles showed no increase in temperatures and remained in-


t t-






60 BULLETIN FLORIDA STATE MUSEUM Vol. 14

active. Thus although the data are too incomplete .and are based
on too small a sample both in numbers of turtles and in conditions,
they indicate that predictions 1 and 3 above and the theories ex-
pressed in the preceding paragraph are worthy of further study.
Selection for size both during the Pleistocene and at the present
time is probably not a single-factor selection, such as the ability
both to survive and recover from cold. Tinkle (1961) in considering
the larger average size of northern Sternothaerus populations sug-
gests that it is advantageous for populations in cold regions to
produce more offspring in order to insure that some of them survive,
and that the only way a turtle can produce more eggs is by
increasing the size of its encasing armor. I think this may be an
important factor.
Auffenberg (1964) shows decreases in size of the tortoise genera
Geochelone and Copherus in North America through the Pleistocene,
and suggests that the extirpation of Geochelone was due to the fact
that it did not learn to dig holes as did Gopherus. Box turtles in the
midwest are about the size of the smallest Gopherus (G. berlandieri),
and they either dig holes or hibernate in piles of leaves and debris,
in caves, holes of other animals, or crevices. In this respect a
smaller turtle would be expected to have a wider selection of
hibernacula, and perhaps deeper and/or better insulated hibernacula
than would a larger turtle.
Another important factor in the size-temperature relationship is
availability of food and efficiency of metabolism, particularly in re-
lation to warm days in winter. Townsend (1931) and Hibbard
(1960) have discussed the plight of giant Galapagoes Island tortoises
that survived cold winter nights in the United States from temper-
ature as a direct effect, but died of gastritis from fermentation of
foods eaten during the day and not properly digested during the
cold-induced lower metabolism at night. In both this case and the
case cited above where two large Florida turtles failed to show an
increase in temperature on warm winter days, the effect of the cold
is presumed to be cumulative in much the same way that an unheated
building becomes progressively colder through the winter. ,Gastri',s
would most likely have Accurrcd in the giant tortoises through an
accumulation of food residues resulting from- progressively poorer
metabolism which in turnmelilted from progressively lower body
temperatures.
This provides another suggestion to account for the, large size
of major in northwestern Florida and the small size of triunguis in
I *






MILSTEAD: BOX TURTLE EVOLUTION


southeastern Texas. Selection in southeastern Texas may demand
a small turtle that can reach activity temperature quickly on warm
winter or spring days, obtain a small but sufficient quantity of food
in a short time, and metabolize that food rapidly enough to avoid
problems of fermentation. Among other considerations still to be
made are those of physiological adjustments in response to temper-
ature. We are just beginning to understand some of these responses
in relation to heat gain (see papers by Norris, Dawson, and Tucker
and discussions of these papers and others in Milstead, 1967b), but
our knowledge of physiological responses of poikilotherms to cold
is sadly inadequate.

VERTICAL DISTIBUTION: T. c. triunguis is presumed to have
evolved from a western population of T. c. putnami that became
isolated sometime in the Pleistocene, through some such factor as
the opening of the Mississippi River embayment caused by rising
seas following a glacial stage. The evolution of triunguis appears to
have taken place in a rather straight-line fashion without the reversals
that punctuated the evolution of bauri and major. This was, at least
in part, a function of the amount and location of the area involved.
The evolution of bauri and the later evolution of major took place
in relatively small geographic areas under climatic conditions that
were relatively uniform, while the evolution of triunguis took place
over a much larger area with more variable climates.
Some evidence suggests climatic conditions favorable for putnami
existed in the midwest at times during the Pleistocene (Hibbard,
1960; Auffenberg and Milstead, 1965; Milstead, 1967), but little
evidence that these conditions either brought about a reversal to
putnami characteristics or a reinvasion of southeastern putnami into
the midwest, although they may have had a "braking" effect on the
development of triunguis characteristics. The putnami-triunguis in-
termediate forms undoubtedly did come into contact with both south-
eastern putnami and carolina, but the influence of the southeastern
putnami was probably most important along the Gulf Coast, and the
influence of carolina cannot be detected !Wtr limited fossil material
fhom the midwest.
W4sfiithe fossil turtle ffisin the central United States are,
like the Florida finds, limited to one or two specimens with two
notable exceptions, Ingleside and the Friesenhahn Cave (Milstead,
1956, 1959, 1967). The Ingleside locality, near Ingleside, San Pa-
tricio County, Texas, was originally dated at about 20,000 years
4 9 ^ -r-


---I






BULLETIN FLORIDA STATE MUSEUM


B.P., but it is now thought to be about 50 to 80 thousand years
B.P. Remains of at least 12 box turtles have been taken from the
deposits. At the time the turtles died the area may have been a
coastal bog. The Friesenhahn Cave, near San Antonio, Bexar County,
Texas, dated at 10 to 14 thousand years B.P., has yielded remains of
at least 122 box turtles when these turtles died they were probably
using the cave as a hibernaculum. The age of the Friesenhahn
deposits and the quantity of turtle remains seem to make a good case
for the old idea that the Wisconsin glaciation sent killing cold waves
southward in front of the advancing ice. A more likely explanation
is that the assemblage of fossil remains in the Friesenhahn Cave was,
like assemblages of nonfossil remains found in modem hibernacula,
accumulated at the rate of one, two, or a few per winter over many
winters. Always disturbing when studying fossils is the fact that
we are working with the minority that did not survive a given
situation rather than the majority that did. The same discomfort
can be carried over to Recent specimens in museums. Our so-called
random samples represent the minority that were indiscrete enough
to encounter a collector, except in the rare cases where all or most
of a population was available and the collector did sample randomly.
The oldest known turtles that show characteristics of triunguis
are from the Sangamon deposits in Kansas and Texas (MP 26957,
UMMP 38367, MCZ 2170, and UT 30907-19B) and are identified
as Terrapene carolina putnami xt triunguis (Milstead, 1967). When
good specimens are available from early Pleistocene deposits west
of the Mississippi River, they may show that the evolution of
triunguis actually began in the early Pleistocene, as did the evolution
of bauri. At the present time no evidence exists for or against this
possibility. The specimens from the early Pleistocene of Kansas and
Texas tentatively referred to putnami (above and Milstead, 1967)
consist of one complete anterior lobe of a plastron (UT 882-315)
and carapacial and plastral fragments of several turtles. The charac-
ters of carapace shape, which are the most useful characters in
distinguishing individual specimens of putnami and putnami xt tri-
unguis, are not available in these early fragments. As noted above,
the fragments arg tatively identified as putnami solely on the
basis of their size, although size alone does not eliminate the possi-
bility that the fragments could be putnami xt triunguis. In the
evolution of bauri, small size became a character early in the fossil
record, but in triunguis selection for small size did not approach
completion until after the Wisconsin glaciation. When maximum
& t J -.


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


lengths (either actual or calculated) are compared (Table 5) for
specimens from west of the Mississippi River, it becomes apparent
that maximum lengths remained fairly stable throughout the Pleis-
tocene, though average lengths may have progressively decreased.
Averages based on 5 carapaces, 11 anterior lobes of plastron, and





"z,. ^I' -
^.~1 -11 *( ,^ ^ ^ ;-.. ,.
.^ i .y i r .;s -


. : #2


FIGURE 11. Fossils of Terrapene carolina. Upper row in both A and B, T. c.
putnami xt triunguis, Ingleside, San Patricio County, Texas. Lower
row in both A and B, T. c. triunguts (with T. c putnami influence),
Friesenhahn Cave, Bezar County, Texas.






BULLETIN FLORIDA STATE MUSEUM


12 posterior lobes of plastron from the Ingleside locality (50-80
thousand years B.P.), and 25 carapaces, 122 anterior lobes, and 116
posterior lobes from the Friesenhahn Cave (10-14 thousand B.P.)
show the following:
Ingleside: 174 mm 70 mm 95 mm
Friesenhahn: 163 mm 68 mm 92 mm
These measurements include all the turtles, both large and small
from each locality. In Florida giant and small box turtles occur in
different zones of deposition, particularly at Haile VIII A (above
and Auffenberg, 1967), an important fact in the evolution of bauri.
Of equal importance in the evolution of triunguis is the fact that no
such size distinction is evident at either the Friesenhahn Cave or
at Ingleside: giant and small turtles were found side by side in the
various zones of deposition. The only evidence of possible triunguis-
to-putnami reversals is the Spring Branch (Houston) specimen re-
ported by McClure and Milstead (1967) taken near the Texas coast
from deposits intermediate in age between the Ingleside and
Friesenhahn deposits; it appears to be triunguis with no detectable
influence of putnami. If additional Houston specimens indicate that
"pure" triunguis existed prior to the Wisconsin maximum, at least
a partial reversal would have been necessary to produce the Friesen-
hahn specimens. On the other hand, additional Houston specimens
may show that most of the population now represented by one
specimen did exhibit some putnami characteristics.
At the moment it seems best to suggest that three allelic com-
binations for size existed in Texas box turtles during the Wisconsin
glaciation: one for "giants" the size of putnami, one for small turtles
the size of modern Texas triunguis, and one for an intermediate
form somewhat larger than modern Texas triunguis. All three existed
at the time the Ingleside and Friesenhahn deposits were made
(Figure 11), but in Recent times the giant form became extinct,
the intermediate form became restricted to the northern part of the
subspecies range (Kansas and Missouri), and the small form became
restricted to the southern part (Arkansas, Louisiana, Oklahoma.
Texas).
The fossil box turtles from the Friesenhahn Cave and from other
late Wisconsin deposits are identified as Terffee carolina triunguis
(Milstead, 1967) in spite of the larger size of some of the fossils.
Some differences in shape also exist in the fossils. Of the 28 carapaces
from the Friesenhahn Cave, 9 closely approximate the shape of
'- *5


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


modem Texas triunguis, 6 closely approximate putnami from Florida,
10 are intermediate between the two, and 3 have the shape of
mexicana and yucatana. Differences in shape still exist today;
modem triunguis from Missouri are closer to putnami than modem
triunguis from south-central Texas, and mexicana and yucatana are
considered to be closely related to triunguis or putnami xt triunguis.
The plastral ratios of the Friesenhahn specimens are the same as
modem triunguis in all but the intcrpectoral and interabdominal
seam ratios (cf. Tables 2 and 4). The two exceptions are outside
the observed ranges of the averages in modern triunguis, but the
differences are not statistically significant. When the differences
between the Friesenhahn fossils and the modern triunguis are com-
pared with differences between any two living subspecies (e.g.,
triunguis and major), it is obvious tha the differences between
Friesenhahn and modem triunguis are minor; that the only real
difference is in the larger size of a very few of the fossils; that this
difference may be due to allelic differences in a single pair of genes;
that other differences are less than those existent between some
samples of modern triunguis; and that all of the differences com-
bined fall below the level for taxonomic recognition.
The fossils from Ingleside are more difficult to interpret than
those from the Friesenhahn Cave. The shapes of the Ingleside
turtles are either intermediate between putnami and triunguis (3
specimens), like triunguis (1 specimen), or like mexicana and yuca-
tana (1 specimen). The plastral ratios place the Ingleside turtles
intermediate between modem major and modern triunguis: the in-
tergular ratio is like that of major, the interhumeral ratio is inter-
mediate between that of major, and that of triunguis, and the inter-
pectoral, inferfemoral, and internal ratios fall within the ranges of
triunguis (cf. Tables 2, 30-44, and 4, 86). The interabdominal ratio
of the Ingleside turtles (29%) falls outside the observed averages
for any living or fossil samples of the Carolina Group, but the
Friesenhahn turtles have a ratio of 31% and modem triunguis in
south-central Texas have a ratio of 32%.
Because of the apparent influence of both putnami (and/or
major) and triunguis, I have identified the Ingleside fossils as
T. c. putnami xt triunguis 'fMilstead, 1967). This designation, which
I still advocate, takes the position that the Ingleside turtles represent
a stage on the chronocline from putnami to triunguis, although other
interpretations are possible. If triunguis, like'bauri, had evolved by
the time the Ingleside deposits were made, the identification T. c.
e


1969






BULLETIN FLORIDA STATE MUSEUM


triunguis or T. c. putnami x triunguis might be made. The coastal
location of the Ingleside site could mean that the fossils found there
were T. c. triunguis in which the environment had favored the ex-
pression of some putnami characteristics. Occasional specimens of
modern triunguis from the Texas gulf coast exhibit some major
characteristics, although samples from the area (Table 2, 32T) do
not show this in their averages. The possibility of horizontal inter-
gradation (T. c. putnami x triunguis) is also related to the coastal
position of Ingleside. T. c. putnami and T. c. triunguit may have
been intergrading on the Texas coast during the Wisconsin glaciation,
much as major and triunguis intergrade on the Louisiana and Miss-
issippi coasts today. Both the identification as triunguis or as put-
nami x triunguis must await the discovery of substantial fossil
material contemporaneous with the Ingleside turtles, but located
more inland and northeastward.
Another possibility is that the mexicana-yucatana shape exhibited
by one of the Ingleside turtles and the putnami-like ratios may have
come to Ingleside from yucatana, which I presume to have been
isolated from the other members of the species at least once by
Ingleside times. The difficulties with this hypothesis are (1) the
uncertainty that the ranges of the Yucatan And Texas turtles were
united during Ingleside times, and (2) lack of evidence that the
mexicana-yucatana shape had its origin in yucatana rather than in
putnami xt triunguis or in early triunguis.
PRESENT INTERGRADATION: Samples 45CT, 46CT, and 47CT
(Figure 1 and Table 2) represent intergrade populations between
T. c. carolina and T. c. triunguis. All three samples contain some
individuals with the shape and color of carolina, some with the
shape and color of triunguis, and some with intermediate shapes and
colors. The interfemoral ratio is the only plastral ratio that will dis-
tinguish carolina and triunguis. All three of the intergrade samples
have interfemoral ratios (11%) falling within the observed range of
carolina (10%-12%) but outside the observed range of triunguis
(12%-16%). The number of toes on each hind foot is intermediate
in all three samples: 45CT, 3 toes lPc' 4 toes 82%, 46CT, 3 toes
29%8 4 toes 71%; 47CT, 3 toes 60,, 4 toes 40%.
Samples 27M rB.4 T, 29MT, and 30MT. (Figure 1 and Table 2)
represent intergrade populations iqtween T. c. major and T. c. tri-
unguis. Some specimens in all four samples have the shape of major,
some have the shape of triunguis, and some have intermediate shapes.
The color of major (see discussion of major) except for the "fire-




4'~2~,


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


marked" pattern is the same as that of bauri, carolina, and triunguis.
This influence of the other subspecies in major makes interpretation
of color in intergrade populations difficult. Most of the specimens in
all four samples of intergrades have the coloration of triunguis, but
a few specimens in all four samples have the coloration of carolina,
a few specimens in samples, 27MT, 28MT, and 29MT have the col-
oration of bauri, and one specimen in sample 27MT has the "fire-
marked" pattern.
In three of the samples the ratio between the anterior and pos-
terior plastral lobes and the interpectoral ratio are within the range
of triunguis and outside the range of major (Table 2), but the ra-
tios in all three samples are at the extreme of the triunguis range
closest to major. The anterior lobe ratio of sample 30MT is close
to major and the interpectoral ratio is well within the range of
triunguis. The intergular and interhumeral ratios of samples 27MT,
29MT, and 39MT are intermediate between major and triunguis,
while these ratios in sample 28MT are within the range of triunguis
but close to major. The interfemoral ratio of sample 27MT is neither
major-like nor triunguis-like, but is close to both. The interfemoral
ratio is like both major and triunguis in sample 28MT, and like
triunguis in samples 29MT and 30MT. Three toes on each hind foot
occur in 67% of the individuals in sample 27MT, and in 100% of the
individuals in samples 28MT, 29MT, and 30MT.
Samples 24CMT, 25CMT, and 26CMT (Figure 1 and Table 2)
represent intergrade populations between T. c. carolina, T. c. major,
and T. c. triunguis. Some specimens in all three samples have the
shape of carolina, some have the shape of major, and some have the
shape of triunguis. Some individuals in all three samples have the
coloration of carolina and some have the coloration of triunguis
(Figure 9, D-E). Two specimens in sample 24CMT have the colora-
tion of bauri, but this is presumed to have come from major. The an-
terior lobe and interpectoral ratios of all three samples are like those
of carolina and triunguis. The intergular ratios of all three samples
arc intermediate between the ratio of major and the minimum in
both carolina and triunguisr. Tergl ratio of sample 25CMT
is intermediate between thiaticoof major ad' thp,maxima of both
'barolin and triunguis, Whie the interhumeral ratios 'of samples
24CMT fall within the ranges of both carolina and triunguis. The
interfemoral ratio of sample 24CMT falls within the range of triunguis,
but outside the ranges of carolina and major. The interfemoral ratio
of sample 25CMT fits all three subspecies, while the same ratio In


* 4,


1969






BULLETIN FLORIDA STATE MUSEUM


sample 26CMT falls outside of the observed ratios in all three. The
number of toes on each hind foot is three in 80% of the individuals
in sample 24CMT, 17% in 25CMT, and 47% in 26CMT.

RECENT SPECIMENS EXAMINED: Unless otherwise noted all samples are
from the Austroriparian biotic province of Dice (1943).
24CMT. T. c. carolina x major x triunguis. 81 specimens from Cook, Dekatur,
Grady, Lanier, Lowndes, and Thomas counties, Georgia: AMNH 7525-7, 29883,
35466. 35469, 44657, 44737; FMNH 8074-7, 8212-4, 11282-8, 84743, 34907-8;
UF 4247, 4411, 4414, 4416, 4418-9, 4430, 4443, 4450, 8592, 9711.
25CMT. T. c. carolina x major x triunguis. 34 specimens from Bibb and Jones
counties, Georgia: UF 4225, 4227, 4229 (A-B), 4230-3, 4234 (A-B), 4236,
4237, 4240-1, 4410, 4412, 4420, 4427-80, 4435, 4437, 4440-2, 4444, 4446-8,
4452-3; KU 4608, 46807.
26CMT. T. c. carolina x major x triunguis. 16 specimens from Henry County,
Alabama, and from Baker, Dougherty, Marion, Taylor, and Worth counties,
Georgia: BMNH 1900.7.12.1-6; FMNH 2006 A-C; UF 4228, 4235, 4445,
9409, 9710; UMMZ 67812, 122273.
27MT. T. c. major x triunguis. 86 specimens from Harrison, Jackson, and Stone
counties, Mississippi. Most of the specimens in this sample have been cited in
Milstead (1967, population G). The only addition to the sample has been
UF 11120.
28MT. T. c. major x triunguls. 25 specimens from Forest, Jones, and Lamar
counties, Mississippi. All have been cited in Milstead (1967, population F).
29MT. T. c. major x triunguis. 27 specimens from East Baton Rouge, Living-
stone, St. Bernard, St. Charles, St. Landry, St. Tammany, and Tcrrebonne par-
rishes, Louisiana. Most of the specimens have been cited in Milstead (1967,
population E). The only additions to the sample were: KU 22818, USNM
86871-2 (cotypes of Agassiz's "Cistudo triunguis"), and USNM 100359.
30MT. T. c. major x triunguis. 5 specimens from Amite, Copiah, Rankin, Simp-
son, and Wilkinson counties, Mississippi: KU 46898, 47341-2, 47371; UMMZ
71755, 76459.
31T(M). T. c. triunguis (with some influence of major, as evidenced by an
intermediate shape in several specimens, carolina-like coloration in one speci-
men, and the major "fire-marked" coloration in one specimen). 12 specimens
from Calcasieu, Evangeline, Rapides, and Vernon parrishes, Louisiana: FMNH
29438; UMMZ 92732-5, 92788, 92741, 92744; USNM 64600, 95408, 138879,
138881.
32T. T. c. in guis. AustroripP tic proving. -f nice (1948) an1 'air
'950). 2. 4ecinmeiatm Brazoan, ambers, For : "- .irdin,
Harris, and Jerson counties, Texas. Most of the specispe. ..e been cited
in Milstead (1967, population D). The only addltionsfo the sample were: BM
1949.12.51 and UCM 20779.
38T. T. c. triunguis. Texan biotic province of Dice (1943) and Blair (1950).
55 specimens from Austin, Brazos, Grimes, Leon, Madison, Robertson, and


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


Walker counties, Texas. All of the specimens have been cited in Milstead
(1967, population C).

34T. T. c. triunguis. Texan biotic province of Dice (1943) and Blair (1950).
15 specimens from Colorado, Fayette, Gonzales, Lavaca, Travis, and Victoria
counties, Texas: ASU 58-206 (A-B); BMNH 1949.1.2.48, 1949.1.2.50; KU
3142-4; TCW 4662, 13975, 14957; UT 742, 6347, 9191, 10097-8.

35T. T. c. triunguis. Austroriparian biotic province of Dice (1943) and Blair
(1950). 11 specimens from Angelina, Nacogdoches, Newton, Polk, Rusk, and
Tyler counties, Texas: FMNH 2005; KU 51454; NMS 1882-3, 1885; TCW
460, 13974; UT 852, 8838, 17573-4.

36T. T. c. triunguis. Texan biotic province of Dice (1943) and Blair (1950).
11 specimens from Cooke and Dallas counties, Texas, and Bryan County, Okla-
homa: FMNH 45311; USNM 45338; UT 7456, 7460, 8844-50.

37T. T. c. triunguis. Austroriparian biotic province of Dice (1943) and Blair
(1950). 15 specimens from Howard County, Arkansas; Bossier and Caddo par-
rishes, Louisiana; McCurtain County, Oklahoma; and Bowie and Rusk counties,
Texas: FMNH 26283, 37454, 37461; UCM 11717; UMMZ 64062; USNM
45302-3, 45343; UT 8841, 8908, 9719-21, 9724-5.

38T. T. c. triunguis. Ecotone between Austroriparian, Carolinian, Illinoian, and
Texan biotic provinces of Dice (1943). 14 specimens from Cleveland, Creek,
Hughes, McIntosh, Muskogee, Payne, and Tulsa counties, Oklahoma: AMNH
7761, 16914-7; FMNH 6214, 8315, 8320, 8790; KU 3063; NMS 1317; UCM
11720-1, 11723.

39T. T. c. triunguis. 22 specimens from Garland, Montgomery, Pulaski, Sebas-
tian, and Scott counties, Arkansas: FMNH 26284-6, 26288-90, 29158-9, 29439,
47469; UF 9731-41; KU 51453.

40T. T. c. triunguis. Carolinian biotic province of Dice (1943). 37 specimens
from Benton, Franklin, Madison, and Washington counties, Arkansas; Barry,
Newton, and Stone counties Missouri; and Ottawa county, Oklahoma: AMNII
35449, 64037-9; FMNH 31778-81, 45310, 55084; KU 17368, 18334, 18338,
18353-5, 19343, 19367, 19427-8, 19478, 46752-3, 46758, 46762-3, 46765, 48258;
UCM 11718; UMMZ 60111, 79885-7, 81417; UT 8835-6, 26654.

41T. T. c. triunguis. Ecotone between Carolinian and Illinoian biotic provinces
of Dice (1943). 47 specimens from Bourbon, Cherokee, Crawford, Greenwood,
Labettc, Linn, and Montgomery counties, j. as: KU 3013 4, 3832, 19348,
2(-36-7, 21043-6, 23039. 23337-8, 6, 20,a48-51, 467- 7, 46766-73,
4677 ',8 4*l 4

42T. T. c'tntgiiis. Ecotone between Carolinian and Illinoian biotic provinces
of Dice (1943). 15 specimens from Barton, Cedar, Dallas, Jasper, Lawrence,
St. Clair, Vernon, and Webster counties, Missouri: AMNH 64040, 67276;
FMNH 74778; KU 18387, 18390, 19344, 23040, 48272-4, 50752, 91350,
91356-7; UMMZ 112409. -







BULLETIN FLORIDA STATE MUSEUM


43T. T. c. triunguis. Ecotone between Austroriparian and Carolinian biotic
provinces of Dice (1943). 16 specimens from Craighead, Fulton and Lawrence
counties, Arkansas; and Bollinger, Dunklin, Madison, and Wayne counties, Mis-
souri: AMNH 36422; FMNH 8526-30, 8813-15, 33610-11, 33625, 38113;
UMMZ 75823, 95292, 95295.

44T(C). T. c. triunguis (with some influence of carolina as evidenced by
coloration of some individuals). Carolinian biotic province of Dice (1943). 12
specimens from Callaway, Crawford, Franklin, Iron, Phelps, Reynolds, St. Louis,
and Texas counties, Missouri: FMNH 2667, 28600, 35393-4, 39487-8, 45309;
UCM 11752; UMMZ 69098, 72501, 72503-4.

45CT. T. c. carolina x triunguis. Carolinian biotic province of Dice (1943).
16 specimens from Crawford, Orange, and Pike counties, Indiana; and Daviess,
Edmonson, Henderson, Jefferson, and Meade counties, Kentucky: FMNH 2706,
2831, 83354, 83417, 83432; KU 19353, 47477-9, 47482-3, 48250; UMMZ
60983, 70746; USNM 79443-4.

46CT. T. c. carolina x triunguis. Ecotone between Austroriparian and Carolinian
biotic provinces of Dice (1943). 24 specimens from Colbert County, Alabama;
Alexander, Saline, and Union counties, Illinois; Graves County, Kentucky;
Lafayette and Tippah counties, Mississippi; and Benton, Carroll, Dickson, Fay-
ette, Henry, Madison, and Montgomery counties, Tennessee: FMNH 2219,
18635, 23738, 89228; KU 50505-7; UMMZ 52449, 53226, 53513, 53661-2,
70739, 70741, 72485, 74210, 98581, 99579, 113994-114000; USNM 45304,
95308.

47CT. T. c. carolina x triunguis Ecotone between Austroriparion and Caro-
linian biotic provinces of Dice (1943). 8 specimens from Choctaw and Wilcox
counties, Alabama; and Lauderdale, Oktibbeha, and Webster counties, Mississippi:
FMNH 48824-5; KU 47373; UMMZ 47374, 90133-4, 99581; USNM 62365.


FoSn. SPECIMENS EXAM:NED:

86PT. T. c. putnami xt triunguis. Early Wisconsin glacial stage (50-80,000
B.P.). 5 carapaces, 11 anterior plastral lobes, and 12 posterior plastral lobes
from Ingleside, San Patricio county, Texas. All are in University of Texas col-
lection 30967. Other fossils of T. c. putnami xt triunguis from Sangamon and
early Wisconsin deposits which were examined in this study are cited in Mil-
stead (1967).

87T(P). T.,. trOnguis (with some influence of.putnami as evidenced by
large size). Late Wiscoasin glacial stage (10-14,000 B,P ",' carapaces, 122
anterior plastial lobes, and 116 posterior plastral lobes fr.m the Fricsenhahn
Cave, Bexar County, Texas. All are in University of'Texas collection 938.

FIGURE 12. Terrapene carolina yucatana. A-B, UMMZ 76143, Merida, Yucatan.
C-D, FMNH 27273, Chichen-Itza, Yucatan. E-F, UMMZ 83291,
Chichen-Itza, Yucatan. G-H, UMMZ 73122, Chichen-Itza, Yucatan.


Vol. 14





MILSTEAD: BOX


trY

4. A


TURTLE EVOLUTION


If -77Z'litf


I. -.
B


i
..,1


i'


'ii






BULLETIN FLORIDA STATE MUSEUM


Other fossils of T. c. triunguis from Late Wisconsin and sub-Recent deposits
which were examined in this study are cited in Milstead (1967) and McClure
and Milstead (1967).


Terrapene carolina yucatana (Boulenger)
Figure 12, Table 2 (49)

Cistudo yucatana Boulenger, 1895, Ann. Mag. Nat. Hist., ser. 6, 15:330.
Terrapene yucatana Siehenrock, 1909, Zool, Jahrb. Suppl., 10:492.
Terrapene mexicana yucatana Smith, 1939, Publ. Field Mus. Nat. Hist., Zool.
ser., 24:17-18.
Terrapene carolina yucatana Milstead, 1967, Copeia (1): 168-179.
RECOGNITION FEATURES: Two or more of the plastral ratios of
T. c. yucatana shown in Tables 1 and 2 distinguish it from each of
the other members of the species. The shape of yucatana in lateral
view and in cross-section through the 4th central scute (Figure 2J)
distinguishes it from all other members of the species except T. c.
mexicana. The presence of four toes on each hind foot further sep-
arates yucatana from bauri, mexicana, and triunguis; the smooth or
slightly concave plastron of males from bauri, carolina, major, and
putnami; and the large size from bauri, carolina, and triunguis.
PRESENT DzmTRIBUON: (Figure 1) limited to the Yucatan
Peninsula in the Mexican states of Campeche, Quintana Roo, and
Yucatan (Smith and Taylor, 1950).
GENERAL DESCRIPrION: One of the largest of the living box
turtles, with an average carapace length of 145 mm in 18 specimens
examined and a maximum carapace length of 155 mm (UCM 16147a).
The carapace is elongate and highly vaulted both anteriorly and pos-
teriorly, and with the 3rd central scute elevated in a small hump
(Figures 2 J, 12) as in triunguis. The hump is more emphasized
in yucatana than in triunguis by indentations in the upper parts of
the posterior pleural bones, which in cross-section give the carapace
of yucatana (and of mexicana) a doubly-vaulted appearance (Figure
2, cf. H and J),he plastron of males is smooth or has only a shallow
concavity in the poAi.ter Iqbe (Figure 12 B, D, F, H; cf. 4 l>)..;PhJ
postorbital bar is narrow, cartilaginous, or absent. Of 13 specimens
on which the toes were counted 11 have four toes on each hind foot
and 2 have three toes on one hind foot and four on the other. An
enlarged axillary scale is present in 3 of 18 specimens examined,
and all have urn- or wedge-shaped Ist central scutes. The posterior
,


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


marginal scutes show little flaring, and are similar to those found
in T. c. carolina. A lateral keel does not appear to be present in adult
specimens. The plastral ratios of T. c. yucatana are given in Table 2
(49Y). These appear to be the best criteria for distinguishing T. c.
yucatana and T. c. mexicana.
Two types of color pattern are present in T. c. yucatana: the horn-
colored shell with dark radiating lines described for triunguis and
the "fire-marked" pattern described for major. The latter pattern is
the predominate one in the yucatana specimens examined. In mexi-
cana the "fire-marked" pattern shows minimal melanism; i.e., horn
or straw-colored scutes with black borders, but in yucatana, com-
pletely melanistic individuals are of frequent occurrence.

VEImcTIC DiSTRIBUmoN: No fossils of T. c. yucatana have yet
been found. Remains of this subspecies found in an Indian site in
Yucatan are quite recent.
The "fire-marked" coloration and white head of yucatana relate
it to major and possibly to putnami. The ratio between the anterior
and posterior plastral lobes and the intergular and interhumeral seam
ratios of yucatana also place it close to major or to bauri x major in
western Florida, but these ratios place it even closer to the Reddick
IB putnami x bauri fossils from Florida (Tables 2 and 4). Because
of these traits, I consider yucatana to be a descendent from a putnami
or putnami xt triunguis population that became isolated on the Yuca-
tan Peninsula in pre-Sangamon or Sangamon times (Milstead, 1967).
I suggest that during one of the glacial stages (possibly the Illinoian)
when sea levels were low, a coastal plain existed around the gulf
coast from Florida to Yucatan and that putnami ranged throughout
the available habitat. With rising sea levels, the coastal plain be-
came inundated in southeastern Mexico and the turtles on the Yuca-
tan Peninsula became isolated from the rest of the species.
During the Wisconsin glaciation the coastal plain again became
habitable and Yucatan turtles dispersing northward came into con-
tact and intergraded with Texas turtles dispersing southward. At
fjA' time the yucatana shape may have bee- .'nsmitted northward
atl(he Inglcside turtles. Whether or not thc. finge of yucatana wasomr'
in cdfts et with the range of the northern turtles by Ingleside times
is questionable, as is the origin of the yucatana shape. The essential
features of the yucatana shape are the "humping of the carapace
posteriorly, as in triunguis, and indentation of the posterior pleural
bones to produce the combined effect of a doubly-vaulted carapace

V






BULLETIN FLORIDA STATE MUSEUM


(Figure 2 J). Indentations of the posterior pleural bones occur
rarely in fossil and Recent specimens of bauri and carolina. The
shape has not been recorded in modem triunguis, but its presence
in Texas fossils indicates that it could have originated in putnami xt
triunguis populations in southern Texas and northern Mexico, and
could have been favored in southern populations (mexicana and yuca-
tana), but not favored in northern populations (triunguis).
Other characters in yucatana that may show a triunguis influence
are the loss of the concave plastron of males, reduction of the post-
orbital bar, and the color pattern of dark radiating lines, all of which
could have developed independently. Two yucatana characters that
apparently did develop independently are the high interfemoral seam
ratio (21%), which falls well outside of the observed averages for
all fossils and Recent samples of the Carolina group (Tables 1, 2, 4),
and the non-flaring posterior marginal scutes. These open the way
for an alternative suggestion on the evolution of yucatana: it may
be a direct descendent of the proposed ancestor close to the base
of both the Carolina and Ornata Groups (see the Genus Terrapene).
The oldest fossils of the Carolina Group show that T. c. carolina
and T. c. putnami had already developed their characteristics by the
beginning of the Pleistocene (see above), and no intermediate forms
other than later day intergrades have been found. The characteristics
of yucatana suggest such an intermediate, providing that the highly
vaulted carapace of yucatana is considered to be a relatively recent
development, with or without the influence of triunguis. Without this
trait an early yucatana would be a flat turtle with a well-developed
postorbital bar (although some individuals may have had it re-
duced), a size intermediate between carolina and putnami, frequency
of axillary scale intermediate, plastral ratios similar to putnami, non-
flaring marginals as in carolina, and an elongate shell as in putnami
(although some individuals may have had a "round" shell as in
carolina).
From this prototypic yucatana populations east of the Appala-
chians could have developed into carolina by decreasing in size, re-
ducing the post-orbital bar (or favprilg.a reduced bar), developing
(or favoring) a round shape, elevating tLe carapace and developing
a concavFoit strong in males, and modifying some of the plastral
ratios. West or south of the Appalachians, populations could have
developed into putnami by increasing in size, developing flared
marginal scutes, favoring development of the enlarged axillary scale,
elevating the carapace and developing a concave plastron in males,


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


and modifying (although only slightly) some of the plastral ratios.
The highest interfemoral ratio in the non-Yucatan samples of the
Carolina Group is 16% in two samples of T. carolina triunguis
(Tables 1, 2), which shows a considerable reduction from the
21% of yucatana, but individual specimens of modem carolina and
triunguis and one fossil of putnami (UF 7043, Haile XII B) have
interfemoral ratios of 20% or over. Average interfemoral ratios of
living Terrapene ornata are frequently 21% or over, and the Pliocene
fossils (USNM 5983 and UMMP 45689) have ratios of 23% and
18%. Both living and fossil representatives of T. ornata are flat
turtles with smooth posterior plastral lobes in males, as suggested
for the yucatana prototype, and the size of the extinct T. o. longin-
sulae is comparable to that of modem T. c. yucatana. Thus ornata
could have descended from the prototypic yucatana by loss of the
postorbital bar, development (or favoring) of a round shape, and
modification of some of the plastral ratios. Superficially at least, it
seems that to make ornata out of the yucatana prototype would have
involved fewer steps than to make carolina or putnami.
All that is needed to support this suggested evolution of the
Carolina and Omata groups is one specimen of the yucatana proto-
type, but it has not been found, and all the characteristics of modem
yucatana can be attributed to evolution from putnami or putnami xt
triunguis. Most of the traits have already been considered in this
sense (above), but the interfemoral seam ratio and the nonflaring
marginals remain to be explained. Three explanations of the inter-
femoral seam ratio come quickly to mind: (1) as suggested above,
the description of putnami based on individual specimens and inter-
grades from Florida may not be defining the characteristics of put-
nami exactly; (2) as noted above, the characteristics of putnami west
of the Mississippi River are unknown and may not agree with eastern
putnami; and (3) yucatana may have increased its interfemoral ratio
in descending from putnami xt triunguis, while triunguis decreased
its interfemoral ratio. Reduction in flaring of the marginals from the
condition found in putnami has already been demonstrated in the
evolution of bauri, major, anl t anguis, although yucatana has car-
,ied the reduction fartbhertn any of the other modem subspecies.
Thus for the present no serious consideration need be give ti---
the suggestion of a prototypic yucatana as the ancestor of both the
Carolina and Orata groups. If, however, someone someday dis-
covers an early Pliocene fossil of a flat, yucatana-like Terrapene, the
suggestion will have to be reconsidered.







BULLETIN FLORIDA STATE MUSEUM


SPECIMENS EXAMINED:
49Y. T. c. yucatana. Yucatan biotic province of Goldman and Moore (1945)
and Goldman (1951). 18 specimens examined from the states of Campeche and
Yucatan, Mexico. Ten of the specimen numbers are given in Milstead (1967,
Population K). The eight additions to the sample are: BMNH 1974.3.5.45-7;
KU 71773, 75657-9; and MCZ 9512. The three British Museum specimens are
the cotypes of the subspecies (Boulcnger's Cistudo yucatana).


Terrapene carolina mexicana (Gray)
Figure 13, Table 2 (48)

Cistudo (Onychotria) mexicana Gray, 1848 (1849), Proc. Zool. Soc. London,
16: 16-17.
Cistudo mexicana Gray, 1855, Cat. Shield reptiles Brit. Mus., pt. 1:40.
Onychotria mexicana, Duges, 1888, La Naturaleza, ser. 2, 1:107-108.
Cistudo carolina var. mexicana Boulenger, 1889, Cat. chelonians, rhyncoce-
phalians, crocs Brit. Mus.: 118.
Terrapene mexicana Baur, 1893, Amer. Nat., 27:677.
Terrapene mexicana mexicana Smith, 1939, Publ. Field Mus. Nat. Hist., Zool.
Ser., 24: 17-18.
Terrapene carolina mexicana Milstead, 1967, Copeia (1): 168-179.
Terrapene goldmani Stejneger, 1933, Proc. Biol. Soc. Wash., 46: 119-120.
Terrapene yucatana Ditmars (nec Boulenger), 1934, Zoologica, 17: 34-36.
RECOGNITION FEATURES: Two or more of the plastral ratios of
T. c. mexicana shown in Tables 1 and 2 distinguish it from each
of the other members of the species. The shape of mexicana in lateral
view and in cross-section through the 4th central scute (Figure 2 J)
distinguishes it from all other members of the species except T. c.
yucatana. The presence of three toes on each hind foot further sep-
arates mexicana from carolina, major and yucatana; the smooth or
only slightly concave plastron of males from bauri, carolina, major,
and putnami; and the large size from bauri, carolina, and triunguis.
PRESENT DISTRIBUTION: (Figure 1) limited to a relatively small
area in southwestern Tamaulipas, northeastern San Luis Potosi, and
northern Vera Cruz (Smith and Taylor, 1950). The area is ecotonal
between the Tamaulipan, Vera Cruz, and Sierra Madre Oriental biotic
provinces of Gofdmiin andi-obre (1945) and Goldm- ,951). For
a detailed study on the herpetplogy of the area see Martin (1958).
GENERAL DESCRIPTION: One of the largest of the living box
turtles, with an average carapace length of 145 mm in 29 specimens
examined, and a maximum carapace length of 173 mm (cotype


Vol. 14






1969 MILSTEAD: BOX TURTLE EVOLUTION 77

1947.3.5.48 in the British Museum). The carapace is elongated and
highly vaulted, both anteriorly and posteriorly, and with the 3rd
central scute elevated in a small hump (Figures 2J, 13) as in triunguis.
The hump is more emphasized in mexicana than in triunguis by in-


















C -----. D








E F










FIcUnE 18. Tegrapne carolina mexicana. A, AMNH 71612, Pujal, San Luis
Potosi. B, KU 89981, Valls, San Luis Potosi. C-D, USNM 46251
(type of T. goldmani), Chijol, San Luis Potosi. E-F, UMMZ
103198, Gomez Farias, Tamaulipas. G-H, UMMZ 102925, Gomcz
Farias, Tamaulipas.






BULLETIN FLORIDA STATE MUSEUM


dentations in the upper parts of the posterior pleural bones which
in cross-section give the carapace of mexicana (and of yucatana) a
doubly-vaulted appearance (Figure 2 cf. H and J). The plastron of
males is smooth or has only a shallow concavity in the posterior lobe
(Figure 13 D, F, cf. 4 D). The postorbital bar is narrow, cartilagi-
nous, or absent (Figure 5). In 17 specimens on which the toes were
counted, 16 had three toes on each hind foot, and 1 had four. An en-
larged axillary scale is present in 3 of 30 specimens examined, and
all have urn- or wedge-shaped 1st central scutes. The posterior
marginal scutes are similar to T. c. triunguis in their degree of flaring.
A lateral keel above the bridge may be present. The plastral ratios
of T. c. mexicana are given in Table 2 (48Mx). These appear to be
the best criteria for distinguishing T. c. mexicana and T. c. yucatana.
Four types of color pattern are present in T. c. mexicana: the
three patterns described for T. c. triunguis, and the "fire-marked"
pattern described for T. c. major and T. c. yucatana. Of the three
triunguis patterns, the horn-colored shell with dark radiating lines
appears to be the one of most frequent occurrence in T. c. mexicana.
The "fire-marked" pattern was described above as varying continu-
ously from horn-colored scutes with dark borders to completely
melanistic scutes. T. c. mexicana does not appear to become as mel-
anistic as some individuals of major and yucatana, and the pattern
of horn-colored scutes with dark borders (Figure 13, C-D) is most
frequent. Occasional specimens of mexicana have the white or white-
blotched head of major and yucatana.
VERTICAL DLsTRmIBTION: T. c. mexicana is another form for
which no fossil representatives have been found. Earlier (Milstead,
1967), I suggested that mexicana may have evolved from putnami xt
triunguis in post-Wisconsin times because some of its characteristics
appear to have come from triunguis, while others appear to have
come from major or putnami. That the latter characteristics may
have come from yucatana was somehow overlooked, but this seems
to be a better explanation in view of the fact that mexicana has the
same shape as yucatana, and yucatana is closer to mexicana in both
time and space than is putnami or major. When yucatana is regarded
as the contributer of the maior-like characteristics, it becomes
necessary'to consider mexicana as having orikftAted through inter-
gradation between triunguis and yucatana, because the traits that
distinguish mexicana from triunguis are the traits that came from
yucatana, while the traits that distinguish mexicana from yucatana
are the traits tfnt came from triunguis.
4 4


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


I suggested above that triunguis and yucatana intergraded in
Mexico during Wisconsin times, and mexicana fits the hypothetical
intergrades in both morphology and geography. The isolation of
mexicana may be assumed to have taken place in post-Wisconsin
times, first from yucatana and later from triunguis. I suggest that
separation from yucatana began shortly after the Wisconsin maximum
glaciation when rising sea levels began to destroy the coastal plain
that served as a dispersal route between Yucatan and northern
Mexico, and that this separation was complete before the separation
of mexicana from triunguis began. At present triunguis ranges no
farther south or west than eastern Texas (Austroriparian and Texan
biotic provinces of Dice, 1943; Blair, 1950) and is separated from
mexicana by the arid Tamaulipan biotic province of Dice (1943),
Goldman and Moore (1945), Blair (1950), and Goldman (1951).
It is my contention that the present Tamaulipan province developed
in relatively recent times following the period of humidity associated
with the Wisconsin glaciation, and that triunguis withdrew north-
ward as arid conditions progressed leaving the old intergrade popu-
lation behind.
The suggestion that mexicana was in contact with triunguis after
its separation from yucatana is supported by the fact that most of
the characteristics of mexicana are triunguis characteristics. Aside
from the yucatana-like shape and size, mexicana differs from triunguis
only in (1) having intergular and interhumeral seam ratios inter-
mediate between those of triunguis and yucatana, (2) having a high
interpectoral seam ratio (Tables 1 & 2), and (3) having a white or
white-blotched head and "fire-marked" pattern in some individuals.
The mexicana yucatana shape can be ignored because of the possi-
bility that it originated in triunguis or putnami x1 triunguis, and size
can be ignored for the same reason. Although the average size of
mexicana and yucatana (145 mm) is larger than in modem triunguis,
it is smaller than in Friesenhahn triunguis.
In addition to fitting well with morphological characters and with
the suggested relationships between trigguis and yucatana, the
intergrade theory for the origin of mexicana also fits well with evolu-
tionary patterns within the species. '~* four subspecies.of Terrapene
cadaia in the-4,tc-h States 're clearly distinct from each other in
morphology, except in areas of intergradation. In discussing mexicana
and yucatana previously (Milstead, 1967), I noted that, 'The two
subspecies now assigned to the species T. menicana are not as distinct
from each other or from T. carolina as the living subspecies of carolina


"-d-






BULLETIN FLORIDA STATE MUSEUM


(bauri, carolina, major, and triunguis) are from each other." When
mexicana is removed from subspecific standing by considering it to
be an intergrade between two other subspecies, yucatana becomes
as clearly distinct as the other subspecies of T. carolina.
The problem of whether to call mexicana specimens T. carolina
mexicana or T. carolina triunguis x yucatana remains to be resolved.
Ordinarily, I do not think that intergrades should be accorded sub-
specific rank unless they have developed distinguishing traits of their
own, and mexicana appears to have done this with only one charac-
ter, the interpectoral seam ratio. I recognize it as a distinct subspecies
on the basis of the interpectoral seam and three other rather weak
reasons that I hope will not be readily accepted as criteria for naming
other subspecies, either within or outside of the genus Terrapene.
First, during its contact with triunguis following separation from
yucatana, mexicana continued to maintain some yucatana-like traits,
although triunguis in post-Friesenhahn times has definitely selected
against two of those traits (size and shape). Second, since its sep-
aration from its northern relatives, yucatana has apparently selected
against the triunguis-like traits which distinguish it from mexicana.
Third, mexicana is presently isolated from both triunguis and yuca-
tana in a habitat that is somewhat different from the habitats of
triunguis and yucatana, and it may be the habitat of mexicana that
is maintaining selection for a mixture of triunguis and yucatana traits.
SPECIMENS EXAMINED
48Mx. T. c. mexicana. Ecotone between the Tamaulipan, Vera Cruz, and
Sierra Madre Oriental biotic province of Goldman and Moore (1945) and
Goldman (1951). 30 specimens from the states of Tamaulipas and San Luis Potosi,
Mexico. Most of the specimen numbers are given in Milstead (1967, popula-
tion J). The only additions to the sample were Senkenberg Museum speci-
mens 22262-3, 22289-90, and 22319, and British Museum specimens 1859.-
5.11.4, 1947.3.5.48, and 1947.3.4.3. The last two specimens listed are the
cotypes of the subspecies (Gray's Cistudo mexicana).

Terrapene coahuila Schmidt and Owens
Figure 14, Table 2 (50)

Terrapene coahulla Schmidt and Owens, 1944, Publ. Field Mus. Nat. IT-'
Zool. scr., 29'(6): 101-103. '. '
REcoGNrTION FEATRES: The flat carapace of T. coahuila (less
that 40% of carapace length) distinguishes it from all other mem-
bers of the Carolina Group. The relatively short anterior lobe of
the plastron (63% of posterior lobe length) distinguishes coahulla


Vol. 14





MILSTEAD: BOX TURTLE EVOLUTION


A











-


FIGURE 14. Terrapene coahuila from Cuatros Cinenegas, Coahuila. A-B, living
specimens. C-D, FMNH 55656, Holotype. E-F, FMNH 47374.

from all of the Carolina Group except T. carolina yucatana, and the
intergular and interhumeral ratios (Table 2, 50 Co) separate coahuila
Sill the CarolidMfytgeorept T. c. carolina and T. c. triunguis.
The *t, elongate carapace of T. coahuila and its dark coloration' ,r
give it the appearance of being intermediate between Terrapene
and Kinosternon (Figure 14). This distinctive morphology provides
a ready recognition feature for identifying Tcoahuila, and I present


B.__~-.....






Q~L





BULLETIN FLORIDA STATE MUSEUM


it only as an identification tool, not as a suggestion of relationship
between the two genera.
PRESENT DIsTRIBUTIoN: Known only from springs near the village
of Cuatro Cienegas, Coahuila, Mexico (Figure 1). The aquatic or
semiaquatic habitat and habits of this species have been described
in detail by Webb, et al. (1963).
GENERAL DESCRIPTION: -A medium-sized box turtle with an aver-
age carapace length of 133 mm and a maximum length of 168 mm
(KU 51432). The height of the carapace in T. coahuila is 34% to
37% of the carapace length when the height is measured from the
bridge to the 3rd central scute along a line parallel with the seam
between the 2nd and 3rd costal scutes. In other living members
of the Carolina Group the height is over 40% of the carapace
length (42%-45% in T. c. bauri, T. c. carolina and T. c. major,
46%-48% in T. c. mexicana and T. c. yucatana, and 48%-50% in
T. c. triunguis). The carapace is elongate in T. coahuila, and may
have a hump on the 5th central scute as described for T. c. putnami.
The plastron of males has a deep concavity (Figure 1, D) to harbor
the carapace of the female during copulation. The postorbital bar
is a broad, heavy span of bone as in T. c. major. All 15 specimens
on which the toes were counted had four toes on each hind foot.
An enlarged axillary scale is present in 78% of 58 specimens ex-
amined. The posterior marginal scutes show about the same degree
of flaring as in T. c. triunguis, i.e. intermediate between T. c. carolina
and T. c. major. The plastral ratios of T. coahuila are shown in Table
2 (50 Co).
The color pattern of the T. coahuila carapace is usually a
uniform dark gray (Figure 14), but occasional specimens have a light
gray shell with dark lines somewhat like the dark radiating lines
found in T. c. triunguis. The head is light to dark gray, and is
frequently mottled with dark gray spots (Figure 14 F) which give
the head an appearance reminiscent of the white-blotched heads of
some specimens of T. c. major and T. c. yucatana.
Two anatomical features that may prove to be of importance in
distinguishing T. coahuila from other members of the Carolina Group
are the presence of cloacal bursae and the penial morphology.
Williams et al. (1960) ,report the presence of cloacal bursae in T.
coahuila, but whel$i or not other livingj4px.Jirtles possess them is
not certain. McDowell (1964) refers to dloacal bursae in Terrapene as
very small or absent. In a study of penial morphology in cryptodiran
turtles, Zug (1966) reports that the plicae internal are reduced in
Lc ^ SE


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


the penis of T. coahuila, while these folds or flaps are enlarged in
T. carolina and T. ornata. He apparently examined only one speci-
men of coahuila and two each of carolina and orata. In any case,
such anatomical features as cloacal bursae and penial morphology
are of only marginal use in this study because the nature of these
characters cannot be determined in fossils.
VERTICAL DISTRIBUTION: As with other box turtles from Mexico,
no fossils of T. coahuila are known. This is particularly unfortunate
because of the unusual morphotype of this species. Auffenberg (1958)
and Legler (1960) take the position that coahuila is the most
primitive known box turtle, and that its flat carapace, heavy post-
orbital bar, and semiaquatic habits are characteristics presumed to
have occurred in the ancestor of both the Carolina and Ornata
groups. I believe that T. coahuila is a descendent of T. c. putnami
xt triunguis (Milstead, 1960, 1967)1, because some of its character-
istics seem to indicate affinity with "advanced" members of the genus,
rather than with "primitive" members. According to my interpre-
tation of the evolution of Terrapene and Emys from Clemmys, for
example, the more primitive members of both Terrapene and Clemmys
must have had a solid contact between the jugal and the pterygoid.
Such a contact is found in T. c. major, which I presume to be a
modern descendent of T. c. putnami coahuila, T. c. bauri, T. c.
triunguis, and T. c. yucatana, all of which I presume to have evolved
from putnami, lack the contact, although some specimens of all four
have a mesially-directed flange on the iugal. Primitive forms of
Terrapene must also have had a solid contact between the prefrontal
and postorbital bones. Such a contact has been found in T. c. carolina,
T. c. major, and T. c. bauri, but not in T. coahuila.
Certain morphological and physiological features of coahuila sug-
gest that its semiaquatic adaptations are secondary rather than
primary. Although it is a flat turtle, T. coahuila has the deeply
concave plastron (in males) generally associated with an elevated
carapace, and this indicates that it descended from ancestors with a
high shell. The well-developed mid-dorsal keel of coahuila also
suggests a high-shelled ancestor. A flat shell is generally associated
jh an aquatic habitat, and I contend that coahuila in assuming an
aquarflc"habitat reproduced the flat shell of the hypothetical ancestral
turtle by recombinations of genetic alleles. Reinvasion of the habitat

'Auffenberg and Milstead (1965) qlso take this position, although the senior
author was not as satisfied with the thesis as was the junior author.



--S






84 BULLETIN FLORIDA STATE MUSEUM Vol. 14

is also indicated by the fact that coahuila is a clumsy swimmer and
has buoyancy problems when in water more than a few inches deep.
Hartweg (pers. comm.) observed that these problems were especially
noticeable when coahuila was compared with mud turtles (Kino-
sternon) that have a shape and habitat similar to that of coahuila.
It would seem that if coahuila had maintained a semiaquatic existence
throughout its history, it would have solved these problems. Other
characteristics of coahuila can be explained in terms of descent from
T. c. putnami xt triunguis: the heavy postorbital bar, short anterior
lobe of the plastron, and four hind toes are putnami characteristics;
while the intergular, interhumeral, interpectoral, and interfemoral
seam ratios are triunguis characteristics. The size is intermediate
between modem and Friesenhahn triunguis, and the frequency of
the enlarged axillary scale could be either a putnami or a triunguis
character.
I suggest that during some pluvial period of the Pleistocene
T. c. putnami xt triunguis invaded the Cuatros Cienegas bolson,
that a population became isolated in the bolson with the retreat of
the main population during an arid period, that increasing aridity
eventually drove the turtles into the water, and that this initiated
the evolution of coahuila (Milstead, 1967). Such a sequence of
events could have taken place anytime in the Pleistocene, but the
presence of deep concavity in the plastral lobe of males in coahuila,
the presence of a heavy postorbital bar, and the absence of these
traits in Wisconsin age fossils of triunguis indicate that the isolation
took place in pre-Wisconsin times. The presence of plastral ratios
similar to those of triunguis indicates either parallel development
of coahuila and triunguis or a Wisconsin influence of triunguis. The
latter possibility is somewhat supported by the knowledge that
Cuatros Cienegas is less distant from the present day range of triun-
guis than is the Wisconsin site in Clovis, New Mexico, where triunguis
fossils have been found, and that representatives of other eastern
species have been recorded in northeastern Coahuila in modern
times (Milstead, 1960).
SIn a previous paper (Milstead, 1967) I suggested that the
evobt of T. coahuila required a much more rapid evolutionary
rate than that found anywnere"else in the genus, but reconsider-
ation of the data does not show this to be true. Only one major
morphological feature is involved, alternation (flattening) of the
carapacial shape. In their evolution from putnami, T. c. bauri (by
shifting its mass posteriorly and T. c. triunguis (by elevating its






MILSTEAD: BOX TURTLE EVOLUTION


shell) changed their carapacial shapes in equivalently short, or
perhaps shorter, periods of time.

SPECMnan EXAMINED
50Co. T. coahulla. Chihuahuan biotic province of Blair (1940, 1950), Dice
(1943), Goldman and Moore (1945), Goldman (1951) and Milstead (1960,
1961). 59 specimens from the Cuatros Cienegas bolson, Coahuila, Mexico.
Most of the specimen numbers have been cited in Milstead (1967). Additions
to the sample include: ASU (field numbers) ACE 821-2; BCB 9435-41; KU
46917-23, 51431, 51433-7, 92623; and UMKC 0496.
The number of specimens examined suggests that enough embalmed
and skeletal specimens of T. coahuila are now available to satisfy
the needs of almost any morphological study. It is hoped that future
collectors at Cuatro Cienegas will keep this in mind. The coahuila
habitat occupies a very small geographic area that may be threatened
by climate and is definitely threatened by agricultural activities.
Conservation plans for the area now being proposed by W. L.
Minckley and others are badly needed.

THE ORNATA GROUP
The Omata Group of box turtles includes two species: Terrapene
ornata with one extinct and two living subspecies distributed over
the Great Plains of North America, and T. nelsoni with two living
subspecies distributed in the western foothills of the Sierra Madre
Occidental in Mexico (Figure 1). The following characteristics
of T. nelsoni distinguish it from T. ornata: (1) slightly larger size
(Tables 2, 3), (2) higher interhumeral and interabdominal and
lower interfemoral and internal seam ratios (Tables 2, 3), (3)
usually higher interpectoral ratios, (4) usually lower anterior lobe
length and intergular ratios, (5) more frequent occurrence of a
weak mid-dorsal keel on the carapace (60% in nelsoni vs. 8% in
ornata), (6) more greatly flaring marginal scutes, and (7) an oval
to elongate shell (vs. a round to oval shell in ornata). A flatter
(scoop-shaped) 1st central scute further distinguishes T. nelsoni
from the living subspecies of T. orinta, but it will not distinguish
F. nelsoni from the extinct T. j longinsulae.
,-. 41. the living mi 'tS the Orata Group are inhabitants
of savannahs, and presumably the one extinct form was also. At
though trees are sparse over most of the geographic range of the
group, the turtles do enter forested areas where und&tr*owtF conlsts
of grass or of relatively opeQ herbaceous vegetation. They avoid






86 BULLETIN FLORIDA STATE MUSEUM Vol. 14

forests with dense undergrowth. The northermost member of the
group, T. o. ornata, inhabits mesic to semiarid grasslands over most
of the Great Plains in the central United States. T. o. luteola occurs
in the arid grasslands of the southern Great Plains in the south-
western United States and north-central Mexico. Legler (1960) de-
monstrates that luteola is better adapted to arid grasslands than
ornata. The wider distribution and greater abundance of ornata
indicate that it is better-adapted to mesic grasslands than luteola,
but the exclusion of luteola by ornata from mesic grasslands is
probably due to competitive factors more complex than humidity
tolerance. Legler (1960) found that ornata kept under arid con-
ditions did not survive, but luteola did. The reverse situation does
not appear to have the same results, although I have not kept
luteola under humid conditions for as long as Legler kept ornata
under arid conditions.
In parts of its range luteola occurs in oak-savannah habitats at
altitudes above 4500 feet. This is the type of habitat in which T.
n. nelsoni, the southernmost member of the Ornata Group occurs
(Milstead and Tinkle, 1967). I presume that the habitat of T. n.
klauberi in Sonora and Sinaloa is also an oak-savannah association
(3500 feet and above), but the turtle may occur more frequently
in desert scrub vegetation at lower altitudes.

SUmN ARY OF EVOLUTION IN THE ORNATA GROUP
The oldest known fossils of the genus Terrapene are identified
as Terrapene ornata longinsulae. Although all the fossils have been
found within the present-day range of T. o. ornata, longinsulae
appears to be most closely related to the living T. o. luteola. Distri-
butional differences are attributed to changing conditions on the
Great Plains during the Pleistocene. At times during the late Cen-
ozoic, the Great Plains are presumed to have been more humid than
they are today, and at other times more arid (Auffenberg and
Milstead, 1965; and other papers there cited). Humid conditions are
presumed to have driven the Ornata Group turtles southwestward,
and arid conditions are presumed to have permitted them to expand
(or driven them) northeastward. During these population shifts,
theaoder T... e.luteoTa is presumed to have evolvedidirectly from
T. o. longinsula1Ea nlsy minor morphological changes. T. o. ornata
may have evolved from a relict population of longinsulae or luteola
left to the north or east during a southwestward population shift
and T. nelsoni may have evolved from a relict population left to the

-'w






MILSTEAD: BOX TURTLE EVOLUTION


southwest during a northeastward population shift. Subspeciation
in T. nelsoni may have occurred (or may be occurring) through the
facility of a partial or complete ecological or physiological barrier.
As in the Carolina Group, the known fossils of the Ornata
Group have been found in the northern and central parts of the
group range, which is one reason for assuming (above and in the
following pages) that evolution proceeded from north to south.
Were it not for the fossils, evolution in both groups of box turtles
might be considered to have proceeded from south to north (see
discussions under the Carolina Group). Within the Ornata Group
the generalized dines in elevation of the 1st, 3rd, and 4th central
scutes; in carapace length, in the anterior plastral lobe length ratio;
and in the intergular, interhumeral, and interpectoral seam ratios,
which I presume to have evolved from luteola to ornata in one
direction and from luteola to klauberi to nelsoni in the other direc-
tion, may actually have evolved in a straight south-north line from
nelsoni to klauberi to luteola to ornata. If this were the case,
nelsoni would be closest of the living representatives to the base of
the Ornata Group. This possibility is supported by a number of
factors that relate nelsoni to the Carolina Group: elongate shell,
frequency of a keeled carapace, and flaring marginals. Despite
these arguments, the fossils do exist and give strong support for the
suggested north-south direction of evolution in both groups. Futher-
more T. ornat luteola, which is presumed to be the oldest living
representative of the Ornata Group, and T. carolina carolina, pre-
sumed to be one of the oldest representatives of the Carolina Group,
are similar in size, both are round and relatively flat in shape, their
plastral ratios (Table 1) form a closer match than do the ratios of
any other forms of the two species groups (Table 1), both have
four toes on each hind foot, both lack flaring marginals, and both
have a high number of radiating lines on each carapacial scute.
The three subspecies of Terrapene ornata and the two subspecies
of Terrapene nelsoni are discussed in mater detail below. The
distribution of members of the Orn~iMroup is given in Figure 1,
plastral ratios and the other data Cthe group are given in Tables 1
and 3, and representatiW,-4ft grotip 'are, shown in Figures 15-18.

Terrapene ornata longinsulae Hay
Figure 15-
Terrapene longnsulae Hay, 1908, Proc. U.S. NatL Mus., 85 (1640): 161-169.
Terrapene ornatalonginsulae Milstead, 197, Copeia (1): 168-179.


1969






BULLETIN FLORIDA STATE MUSEUM


FIcunE 15. A-B, Terrgpene omata longinsulo., I'SNM 5'A.! Hrl.l.t)pe, I..-
middle Pliocene of Lotg'Ilsland, Kansas. C-D, 2. o. longir ulae,
UMMP 87184, lower PliistOcene (Aftbnia l Meade County,. Kansas.
E, T. o. luteola, UMKC 0501, Recent, Dona Ana County, New
Mexico. F, T. o. luteola, UMKC 0500, Recent, Dona Ana County,
New Mexico. G, T. o. luteola, UMKC 0499, Recent, Dona Ana
County, New Mexico. H, T. o. luteola, Stanford University, un-
numbered, Reea t, Chihuahua-Sonora state line.


B- ---- ----- J


G1--- ..- -


-WI
H


Vol. 14


~~~
-9113~






MILSTEAD: BOX TURTLE EVOLUTION


RECOGNITON FEATREs: -The low angle of elevation of the 1st
central scute and the low elevation of the 3rd central scute distin-
guish T. o. longinsulae from both T. o. luteola and T. o. ornata. Lack
of rugosity of the carapacial scutes and nonflaring and nonemargi-
nate marginal scutes will further distinguish longinsulae from the
other two.
PRESENT DISTnmuTION: T. o. longinsulae is a name given to a
box turtle that is thought to be extinct, although its relationship
with T. o. luteola prohibits arrival at a definite conclusion.
GENERAL DSCRPTION: A relatively small box turtle with a
maximum carapace length (USNM 5983) of 125 mm in known
specimens. The shell shape tends to be round in three specimens
examined. The first central scute of the holotype rises at an angle
of about 40* from a line connecting the anterior and posterior
margins of the carapace, versus approximately 30 in T. n. nelsoni,
35-45* in T. o. luteola, 450 in T. o. omata, and 50-55 in T. c. tri-
unguis. The two other longinsulae carapaces have lower angles
(280 in UMMP 37184) than the holotype. The low angles of
elevation of the 1st central scute give the anterior margin of the
carapace a flattened or scoop-shaped appearance in longinsulae. This
appearance is perpetuated in living turtles by both subspecies of T.
nelsoni, but is not so noticeable in luteola and ornata, except when
they are compared with T. carolina (Figure 2, cf. B&K). The height
of the holotypic longinsulae carapace in comparison with the length
is 42% at the third central of the carapace versus 41% in another
specimen (UMMP 37184), 35-41% in luteola, 48% in ornata, 40%
in klauberi, and 45% in nelsoni. Height at the posterior half of the
4th central is 26% in the longinsulae holotype, 22-29% in luteola,
and 30% in ornata and nelsoni. Thus, the slope from the 4th central
to the posterior edge of the carapace in longinsulae is more gradual
than in all members of the group except luteola (Figures 15-18).
The marginal scutes of longinsulae show very little flaring, and thus
are very much as they are in modr/' . carolina. The posterio-
ventral edge of each marginal i^ nginsulae unites smoothly with
the anterioventral ed rtollowing marginal, so the carapace
has`o6 scalloped or emarginate posterior edge as in orata (cf. Figure e w
15, A and Figure 16, A). The longinsulae fossils all have smooth
shells rather than the rugose ones generally exhibIW t omata,
but the validity of this feature as a character is questionable. Al-
though living luteola is never as rugose as ornata, and this is a






90 BULLETIN FLORIDA STATE MUSEUM Vol. 14

distinguishing feature between them, older specimens of ornata tend
to lose their rugosity through abrasion of the shell, and abrasion
might account for the smoothness of the longinsulae fossils.
VEmrICAL DISTRIBUTION: The holotype of T. o. longinsulae
(USNM 5983 from the lower middle Pliocene of Long Island,
Kansas) is the oldest known representative of the genus Terrapene.
Other specimens of longinsulae consist of fragementary to almost com-
plete shells of four turtles from late middle Pliocene (UMMP 45689,
Beaver County, Oklahoma), early upper Pliocene (UMMP 37186 and
45689, Seward County, Kansas), and early (Aftonian) Pleistocene
(UMMP 37184, Meade County, Kansas) deposits. The earliest fossils
of any living representatives of T. ornata are from Wisconsin deposits
in New Mexico and Texas. In spite of the age of the known fossils of
longinsulae and of the hiatus in vertical range, the close similarity
between longinsulae and the living members of the species, particu-
larly luteola, make it inadvisable to consider longinsulae as a dis-
tinct species (Milstead, 1967; Milstead and Tinkle, 1967).


Terrapene ornata luteola Smith and Ramsey

Figure 15, Table 2 (51-54)
Terrapene ornata luteola Smith and Ramsey, 1952, Wasmann Jour. Biol., 10:45.

RECOGNITION FEATURES: -The high number of radiating lines on
the carapace of T. o. luteola distinguishes it from the other living
subspecies, T. o. ornata. Slightly larger size, a tendency toward
horn or straw color, and a tendency to have the plastral hinge located
opposite the 6th marginal scute also distinguish luteola from ornata.
A more sharply elevated 1st central scute, a higher 3rd central
scute and more flaring marginals distinguish luteola from the extinct
T. o. longinsulae.
PRESENT DISTRIBUTION: (Figure 1) Apparently limited to the
northern portions of the Chihuahuan and Sonoran deserts in the
states of Arizona, Chihuahua, New Mexico, Sonora, and Texas (Rocky
Mountain Corridor of Auffcnberg and Milstead, 1965). One specimen
(AMNpI 73720) has been recorded from Guaymas, Sonora, bat
additional specimens are needed before T. o. luteola can be said to
range west of the Sierra Madre Occidental. Intergradation between
luteola and ornata (discussed below) occurs in the extreme northern






MILSTEAD: BOX TURTLE EVOLUTION


part of the Chihuahuan Desert in New Mexico and Texas and in
southeastern Texas.
GENERAL DESCRIPTION: -a medium-sized box turtle (Table 3),
larger than T. o. orata, but about the same size as T. o. longinsulae
and T. nelsoni. The largest specimen examined (UAZ 13092) is
149 mm in carapace length. The shell shape tends to be round or
oval, but oval individuals are never as elongated as T. nelsoni and
most of the members of the Carolina Group. The plastral hinge of
T. o. luteola is usually (over 50% of individuals, see Table 3)
located opposite the 6th marginal scute of the carapace. The degree
of elevation of the 1st central scute is 350 to 450. The elevation of
the 3rd and 4th central scutes places luteola closer to longinsulae
than to ornata. The degree of flaring and emargination of the mar-
ginal scutes and the rugosity of the carapace of luteola appear to
be intermediate between longinsulae and ornata. The plastral ratios
of luteola (Table 3, 51-54) do not clearly distinguish it from ornata,
but in the cases of the anterior lobe, intergular, interpectoral, and
interfemoral ratios, luteola exhibits extremes not found in ornata. The
three specimens of longinsulae for which ratios can be calculated
have interfemoral ratios 18, 23, and 25, which are close to the average
interfemoral ratios exhibited by luteola but outside the observed
averages of ornata.
The most distinguishing feature of luteola is the high number of
radiating lines on the carapace, as Legler (1960) noted. When
counted on the 2nd costal scute, the average number of lines is
12 to 14 in luteola versus 6 to 9 in orata. Infrequently the radiating
light lines may be broken up into spots. Another distinctive feature
of luteola is the horn or straw-colored ground color. One-third of
the specimens in some samples and up to 70% of the specimens in
other samples display this coloration. Some individuals of luteola
exhibit this coloration only in the ground color, while others carry
it to the extreme of having a uniform greenish-horn or straw-colored
shell. This uniform color of some individuals was the main basis on
which luteola was named (Smith and Ramsey, 1952).
VERTICAL DIsTrBUTION: No fossils of T. o luteola have yet been
fouabl luteola is virtually impossible to distinguish frortm longin-
sulae. The differences between the two are so slight that it may
Sbe presumed that luteola evolved from longinsulae by a simple
rearrangement of existing alleles (Auffenberg and Milstead, 1965;
Milstead, 1967; Milstead and Tinkle, 1967). Additional fossil speci-






BULLETIN FLORIDA STATE MUSEUM


means may show that the luteola phenotype was the most frequent
phenotype within the range of variation of longinsulae. Should this
be the case, luteola will have to be considered a synonym of longin-
sulae.
The known specimens of longinsulae are from Kansas and Okla-
homa and are well outside of the present day range of luteola. I
attribute this to displacement during Pleistocene times. It is sug-
gested that during pluvial periods in the Pleistocene, forests extended
into the present day Great Plains from both east and west and
forced the ornate box turtles south and west (Auffenberg and Mil-
stead, 1965; Milstead, 1967; Milstead and Tinkle, 1967). Reinvasion
may have occurred during arid periods in the middle and late
Pleistocene, but a post-Wisconsin return to habitats north and east
of the modem Chihuahuan Desert was prohibited by the spread of
T. o. ornata into those areas. The development of the Chihuahuan
and Sonoran deserts in Recent times may have restricted the range
of T. o. luteola and forced it northward (and possibly eastward).
With its distribution restricted northward by ornata and southward
by the deserts, luteola might be considered as a relict in danger of
extinction in future times.

PRESENT INTERGRADATION: The characteristics used to distinguish
luteola and ornata make it exceedingly difficult to recognize inter-
grades between them. I identify samples 55 and 56 (Table 3) as
T. o. ornata x luteola because they appear to be intermediate between
the two subspecies in the characters of size, % with hinge opposite
5th marginal, % with hinge opposite 6th marginal, number of radi-
ating lines, and % with some trace of horn-coloring. Sample 56 is
from the extreme northern portion of the Chihuahuan Desert in the
ecotone between the Chihuahuan, Kansan, and Navahonian biotic
provinces of Dice (1943), and this is more or less where intergrada-
tion between luteola and ornata is expected. Sample 55, however, pre-
sents some problems because it is from the ecotone between the
Tamaulipan and Texan biotic provinces (Dice, 1943; Blair, 1950),
and is far removed from any known present day contact with luteola.
When we were both working in southeastern Texas and before
'-either of us became seriously interested in box turtles, Auffenberg
and I thought that ornate box turtles from'the sample 55 area
might represent an undescribed subspecies. But in discussing this
with Legler about the time his book appeared (1960), he suggested
that the turtles in question might be ornata-luteola intergrades. Now


Vol. 14






MILSTEAD: BOX TURTLE EVOLUTION


that the data are analyzed, this seems to be the best assumption.
The only difficulty in accepting this view is the lack of contact
between these turtles and the range of luteola, but this hiatus in
range may be more apparent than real. Only a few specimens from
southern Texas have reached collections (I have seen two from
Kennedy County and one from LaSalle County), and no specimens
are known from the Tamaulipan biotic province in northern Mexico.
Additional specimens may show that these intergrades and luteola
are contiguously distributed. The Chihuahuan and Tamaulipan biotic
provinces are separated in Texas by the Balconian biotic province
(of Blair, 1950), which is occupied by T. o. ornata. The Chihuahuan
and Tamaulipan provinces have a broad zone of contact in northern
Mexico, and there are, or have been, faunal exchanges between them
(see Milstead, 1960, for examples of this).
Samples 57-59 appear to be T. o. ornata, but with a slight influence
of luteola, as shown by some horn-colored individuals, high number
of radiating lines, and relatively high percentage of individuals with
the hinge located opposite the 6th marginal (Table 3). One or
more of these traits are also shown by samples 62, 67, 72, and 77, but
these samples are well-removed from luteola and are surrounded by
"good" ornate.

RECENT SPECIMENS EXAMINED
51L. T. o. uteola. Apachian biotic province of Dice (1943). 30 specimens
from Cochise, Pima, Pinal, and Santa Cruz counties, Arizona, and extreme
northwestern Chihuahua: AMNH 64265-6; ASU 62021, 62368; UAZ 13092,
13093 (twice), 13094, 13101-2; UMMZ 13096, 69984, 71179-81, 75815,
114102-3; USNM 20556-61, 20989-93, 21707; Stanford University, one un-
numbered specimen.
52L. T. o. luteola. Ecotone between Apachian and Chihuahuan biotic prov-
inces of Dice (1943). 27 specimens from northern Chihuahua near El Paso;
Dona Ana and Otero counties, New Mexico; and El Paso County, Texas:
FMNH 2002 A-B, 4791; NMS 1876 and two unnumbered specimens; UCM
20780-1; UMMZ 60090-1, 64728-9, 72534-6, 85095, 101286-9; USNM 19061-2,
19394, 19410-2, 45771.
53L. T o. luteola. Chihuahuan biotic province of Blair (1940, 1950), Dice
(1943), Goldman and'l iMj1945I), Goldwan (1951), and Milstead (1960,
1961").%dl.tpecimens from near Gallezo and Ramos, Chihuahua: AMNH
82126; KU 45019, 45055, 51427; UCB 46651-54, 72844-49.
54L. T. o. luteola. Chihuahuan biotic province of Blair (-96fT1l), Dice
(1943), Goldman and Moore (1945), Goldman (1951), and Milstead (1960,
1961). 10 specimens from Brewster, Jeff Davis,.and Presidio counties, Texas:






BULLETIN FLORIDA STATE MUSEUM


BUSM 6445; FMNH 27761; TCW 14897; UMMZ 50012, 100986, 101285,
114354-5; USNM 103676, 107755.
55RL. T. o. ornata x luteola. Ecotone between Tamaulipan and Texan biotic
provinces of Dice (1943) and Blair (1950). 25 specimens from Arkansas,
Calhoun, DeWitte, Jackson, Lavaca, Matagorda, Refugio, San Patricio, and
Victoria counties, Teaxs: BCB 2628, 2631, 8797, 8800; BUSM 575, 2408,
2433-4, 2447, 2450, 7002; TCW 314, 4670, 13980, 14947, 14949; UMMZ
96571, 116266-70; USNM 20959.
56RL. T. o. ornate x luteola. Ecotone between Chihuahuan, Kansan, and
Navahonian biotic provinces of Dice (1948) and Blair (1950). 38 specimens
from Eddy and Lea counties, New Mexico; and Culberson, Gaines, Midland,
Reeves, Ward, Winkler, and Yoakum counties, Texas: AMNH 71298-9, 71303;
BCB 8888; FMNH 2003; NMS one unnumbered specimen; TT 379, 537 A-C,
976, 1767, 1835-6, 1845, 1870-1, 2002-3, 2007, 2017; UCM 6037-9; UMMZ
70199, 72499, 85094, 92746, 121905-6; USNM 19119, 92928; UT 17954-5,
20149-51.


Terrapene orata ornata (Agassiz)

Figure 16, Table 3 (57-82)
Cistudo ornaat Agassiz, 1857, Contrib. Nat. Hist. U.S., 1:445.
Terrapene ornata Baur, 1891, Science, 17:191.
Terrapene ornata ornata Smith and Ramsey, 1952, Wasmann Jour. Biol., 10:48.
Terrapene ornata var. cimarronensis Cragin, 1894, Colorado College Studies,
5:87.
REcoGNiTmON FAnRES: The low number of radiating lines on
the carapace of T. o. ornata distinguishes it from the other living
subspecies, T. o. luteola. Slightly smaller size and a tendency to have
the plastral hinge located opposite the contact between the 5th and
6th marginal scutes also separate omata from luteola. Scalloped
marginal scutes, a more sharply elevated 1st central scute, a higher
3rd central scute, more flaring marginal scutes and, a rugose shell
distinguish ornata from both luteola and the extinct longinsulae
(Figure 2, K).
PREENTr DISTRBUnoN: (Figure 1) Between the Mississippi
River and the Rocky Mountains from southern South Dakota to
south central Texas. East of the Mississippi River, T. o. ornata ex-
tends into Illinois and lidiank-ith,the "PraIe Peninsula" of Schmidt
(1939) and Auffenberg and-Milstead (-1965):- In the more heavily
forested portions of the Austroriparian biotic province (of Dice,
1943) in southeastern Missouri, Arkansas, Louisiana, and eastern
Texas, T. o. ornata appears to be extremely rare, although specimens


Vol. 14








































FcIGRE 16. Terrapene omata onata. A, TT 105, Dickens Col e ,
FMNH 83460, Sapulpa, Oklahoma. D,, FMl't 83346, Amarillo,
Texas. E, UT 14001, Travis County, Texas.


B-- .


Ce


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~






BULLETIN FLORIDA STATE MUSEUM


have been recorded from cleared areas. The subspecies is abundant
in the Austroriparian biotic province on the Texas coastal plain, but
is rare on the coastal plain in southwestern Louisiana, and does not
appear to reach the Mississippi in southeastern Louisiana. Inter-
gradation with luteola (discussed above) occurs in the extreme
northern part of the Chihuahuan Desert in New Mexico and Texas,
and in southeastern Texas. One of the finest ecological studies ever
performed on a reptile has recently been reported for T. o. ornata by
Legler (1960).
GENERAL DESCRIPTION: -The smallest of the box turtles in both
the Ornata and Carolina groups (Table 1). The largest specimen
examined (KU 18358) is 134 mm in carapace length. The shell
shape tends to be round in most cases, but occasional individuals are
somewhat elongated (oval). The plastral hinge of ornata is usually
(Table 3, 57-82) located opposite the contact between the 5th and
6th marginal scutes. Individuals with the plastral hinge located
opposite the 5th marginal and those with it located opposite the
6th are about equally distributed in the samples. The maximum
degree of elevation of the 1st central scute is about 450, carapace
height at the 3rd central is 48% of the carapace length in some
specimens, and height at the 4th central reaches 30%. Thus T. o.
ornata is the highest member of the Omata Group. Flaring of the
marginal in T. o. ornata (Figure 16) is the greatest in the species,
and is approximately the same as in T. carolina triunguis. The
posterioventral edge of each marginal scute in T. o. ornata projects
outward beyond the anteriovcntral edge of the following scute,
and this produces a scalloped or serrate posterior edge of the cara-
pace (Figure 16). The carapacial scutes of many specimens of
ornata tend to be quite rugose, a character not seen in luteola or
longinsulae. This rugosity is not universally present even in medium-
sized specimens of ornata, and older specimens tend to lose it
through abrasion.
When counted on the 2nd costal scute, the number of radiating
light lines averages 6 to 9 in T. o. ornata. In the 26 samples of
ornata (Table 3, 57-82), 11 samples had an average of 8 lines, 8
samples had 7 lines, 6 samples 9, and 1 sample 6. Infrequently the
lines are broken up into spots. Unlike luteola, ornata tends to retain
its pattern throughout life.
VERTICAL DISTRIBUTION: I have examined only two fossils speci-
mens of T. o. ornata, ANSP 13780 and UT 937-201. Both are from
deposits estimated to be of late or post-Wisconsin age (5000-10,000


Vol. 14







MILSTEAD: BOX TURTLE EVOLUTION


B.P.), and both have the carapace elevated posteriorly and scalloped
marginals posteriorly as in modern ornata (Milstead, 1967, Fig. 1 B).
Holman (1963) records fragments of an ornate box turtle from
the Sangamon of Denton County, Texas, but it now appears that the
deposits may be of early Wisconsin age.
It has been suggested (Auffenberg and Milstead, 1965; Milstead
1967; Milstead and Tinkle, 1967) that T. o. ornata may have arisen
from a relict population of luteola left to the north or east of the
main population during one of the Pleistocene population shifts.
This suggestion presumes that, during one of the pluvial periods of
the Pleistocene when luteola (or longinsulae) shifted its range south-
ward, a relict prairie area something like the modern prairie peninsula
(Schmidt, 1939; Auffenberg and Milstead, 1965) in Illinois, Indiana,
and Ohio permitted a population to remain in the otherwise vacated
area. This isolated population evolved into the more mesically-
adapted ornata1, and with return of arid conditions following the
Wisconsin glaciation it dispersed throughout the present day Great
Plains.

RECENT SPECINtENS EXAMINED: Kansan Biotic Province of Dice (1943).
57R(L). To ornata (with some influence of luteola as noted above). 11
specimens from Chaves and Quay counties, New Mexico: FMNH 83355; NMS
267-8; UMMZ 69106-12, 69188.
58R(L). T. o. ornata (with some influence of luteola as noted above). 63
specimens from Baca and Prowers counties, Colorado; Morton County, Kansas;
Union County, New Mexico; Cimarron County, Oklahoma; and Dallam, Hartely,
and Sherman counties, Texas: FMNII 15470; TCW 4671-2; TT 2017-23,
2592, 2593 A-B, 2594, 2596-8, 2613, 2614 A-B, 2640; UAZ 13106; UCM 1179,
11708, 11710-1, 11729-32, and five unnumbered specimens; UMMZ 62470-4,
62476-9, 62480 (twice), 62481-4, 62486-90, 62493-8, 101322-3; USNM 87024.
59R(L). 7'. o ornata (with some influence of luteola as noted above). 42
specimens from Logan, Phillips, Washington and Yuma counties, Colorado; and
Dundy county, Nebraska: AMNH 64262-4, 68242-4; UCM 2560, 3379-80,
3385-8, 3390-1, 3393-6, 3398, 3401, 11688-90, 11692-6, 11712-4, 11716,
11740-1, 11747, 15173; UMMZ 62672-3, 112410; USNM 86907.
60R. T. o. ornata 13 specimens from Adams, Arapahoe, Boulder, Larimer,
and Weld counties, Colorado: UCM 2558-9, 11745, 11750, 13651-5; UMMZ
59843-4, 91911-2.
61R. T. o. ornata. 40 specimens from Barber, Barton, Edwards, Ellsworth,
Ford, Kingman, Kiuwa, Meade, Reno, Rice, and Stafford counties, Kansas;
and Alfalfa and Harper counties, Oklahoma: ASU 60-121; ASU-ACE field
number 62-050; FMNH 16890, 16899; UF 11026, 11027(1), 11028(1);

'That is, more mesically-adapted than longinsulae or luteola.







BULLETIN FLORIDA STATE MUSEUM


KU 1877, 1917, 1936, 1938, 2767, 2856-7, 3214, 6862, 17220-1, 18358, 18369,
18374, 19347, 19485, 41563-65, 50305; UMMZ 62500-1, 64912-4, 96567;
USNM 71531-2, 90427-8, 91031-2, 95273.
62R. T. o. ornata. 17 specimens from Armstrong, Gray, Hutchinson, Potter,
and Randall counties, Texas: FMNH 83346; TT 311, 577-8, 1546, 1546 A;
UMMZ 69100-5; UT 10540, 10598, 10694, 10701, 10742.
63R. T. o ornata. 20 specimens from Andrews, Cochran, Hale, Hockley,
Lamb, and Lubbock counties, Texas: TT 151, 171, 342, 346, 356, 378, 380,
539, 1060 A-E, 1531 A-C, 2006, 2008, 2010, 2015.
64R. T. o. ornata 8 specimens from Hemphill and Lipscomb counties, Texas:
TT 695, 1552 A-C, 1552 E-F, 2159; USNM 45340.
65R. T o. ornata. 9 specimens from Briscoe, Childress, Dickens, and Motlec
counties, Texas: TT 105, 179, 317, 317.2, 544-5, 579, 694, 771, 1563; USNM
92654, 92690, 92732, 92759; UT 10276.
Mesquite Plains Biotic Province of Blair (1950).
66R. T. o. ornata. 8 specimens from Baylor, Clay, Knox, Throckmorton and
Wichita counties, Texas; and Comanche County, Oklahoma: FMNII 13163,
47841; TT 187, 1424, 2400; UMMZ 70349; USNM 83689; UT 10275.

67R. T. o. ornata. 18 specimens from Brown, Callahan, Coleman, Comanche,
Erath, Palo Pinto, and Taylor counties. Texas: AMNH 66108-10, 66116-7;
ASU 326; BCB 6840-1; BUSM 0041, 0098; FMNH 45303-6; TCW 4678,
14898, UMMZ, 85093; UT 21737.
Austroriparian Biotic Province of Dice (1943) and Blair (1950).
68R. T. o. ornata. 12 specimens from Brazoria, Chambers, Galveston, Harris,
Jefferson, and Waller counties, Texas: BUSM 236, 2337-8, 2340, 2407, 2437,
2442, 7004; FMNH 30588; TCW 313, 4677; USNM 100516; UT 21783-4.
Balconian Biotic Province of Blair (1950).
69R. T. o. ornata. 12 specimens from Burnet, Caldwell, Comal, Hays, and
Travis counties, Texas: AMNH 32835, 36720, 67217; BCB 2236, 2787; BUSM
2406, 2658; UT 14000-02; 21652, 26829.
Texan Biotic Province of Dice (1943) and Blair (1950).
70R. T. o ornata. 13 specimens from Bastrop, Brazos, Colorado, Fayette, Lee,
and Walker counties, Texas: BCB 2021, 2109, 2627; TCW 297, 303, 4660,
4669, 14899, 15866, and four uncatalogued in student collections; UMMZ
118178.

71R. T. o ornata. 17 specimens from Bell, Bosquc, Coryell, Limestone, and
McLennan counties, Texas: BMNH 1897.8.11.3-4,, 1897.10.15.4; BUSM
0089-90, 2404, 2657, 3612-3, 5666, 7000-1; FMNH 46287-8; TCW 4676,
15423; USNM 100524.
72R. T. o. ornata. 12 specimens from Dallas, Denton, Hunt, Johnson, Navarro,
Tarrant, and Wise counties, Texas; and Atoka and Carter counties, Oklahoma:


Vol. 14




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