• TABLE OF CONTENTS
HIDE
 Front Cover
 Copyright
 Abstract
 Table of Contents
 Introduction
 Acknowledgement
 Results and discussion
 Taxonomic conclusions
 Systematic accounts
 Interrelationships within the family...
 Literature cited
 Material examined
 Back Cover






Group Title: Bulletin of the Florida State Museum
Title: A Revision of the electric ray genus Diplobatis with notes on the interrelationships of Narcinidae (Chondrichthyes, Torpediniformes)
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00095801/00001
 Material Information
Title: A Revision of the electric ray genus Diplobatis with notes on the interrelationships of Narcinidae (Chondrichthyes, Torpediniformes)
Series Title: Bulletin - Florida State Museum ; volume 29, number 5
Physical Description: p. 171-209 : ill. ; 23 cm.
Language: English
Creator: Fechhelm, Janice D.
McEachran, John D.
Florida State Museum
Publisher: Florida State Museum, University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 1984
Copyright Date: 1984
 Subjects
Subject: Fishes -- Classification   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography : p. 204-205.
General Note: Includes summary in Spanish.
Statement of Responsibility: Janice D. Fechhelm and John D. McEachran.
 Record Information
Bibliographic ID: UF00095801
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: oclc - 11570185

Table of Contents
    Front Cover
        Page 169
    Copyright
        Page 170
    Abstract
        Page 171
    Table of Contents
        Page 172
    Introduction
        Page 173
        Page 174
    Acknowledgement
        Page 175
    Results and discussion
        Page 176
        Page 177
        Page 178
        Page 179
        Page 180
    Taxonomic conclusions
        Page 181
        Page 182
    Systematic accounts
        Page 183
        Page 184
        Page 185
        Page 186
        Page 187
        Page 188
        Page 189
        Page 190
        Page 191
        Page 192
        Page 193
        Page 194
        Page 195
        Page 196
        Page 197
        Page 198
        Page 199
    Interrelationships within the family narcinidae
        Page 200
        Page 201
        Page 202
        Page 203
    Literature cited
        Page 204
        Page 205
    Material examined
        Page 206
        Page 207
        Page 208
        Page 209
        Page 210
    Back Cover
        Page 211
Full Text









of the

FLORIDA STATE MUSEUM
Biological Sciences

Volume 29 1984 Number 5






A REVISION OF THE ELECTRIC RAY GENUS
DIPLOBATIS WITH NOTES ON THE INTERRELATIONSHIPS
OF NARCINIDAE (CHONDRICHTHYES, TORPEDINIFORMES)


JANICE D. FECHHELM
AND
JOHN D. McEACHRAN


UNIVERSITY OF FLORIDA


GAINESVILLE








Numbers of the BULLETIN OF THE FLORIDA STATE MUSEUM, BIOLOGICAL SCI-
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This public document was promulgated at an annual cost of $2,642.00
or $2.642 per copy. It makes available to libraries, scholars, and all
interested persons the results of researches in the natural sciences,
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Publication date: December 3, 1984


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A REVISION OF THE ELECTRIC RAY GENUS
DIPLOBATIS WITH NOTES ON THE
INTERRELATIONSHIPS OF NARCINIDAE
(CHONDRICHTHYES, TORPEDINIFORMES)
JANICE D. FECHHELM1 AND JOHN D. MCEACHRAN2
ABSTRACT: We examined the morphological characters and internal anatomical features
of the electric ray genus Diplobatis (Torpediniformes, Narcinidae) in order to determine
the taxonomic status of the various forms. All specimens from the northern coast of South
America (Colombia to Brazil) were found to be very variable in most morphological char-
acteristics but to be identical in skeletal structure. Based on overlapping proportional
measurements and a lack of distinguishing characters (both internal and external), D.
altenai Boeseman 1963 is synonymized with D. pictus Palmer 1950, and the placement of
D. guanachensis Martin 1957 in synonymy with D. pictus by Bigelow and Schroeder
(1962) is verified. Three subspecies are recognized within D. pictus: D. pictus pictus
Palmer, D. pictus guamachensis Martin, and D. pictus colombiensis new subspecies. D.
ommata (Jordan and Gilbert 1890), from the Pacific coasts of Mexico and Central America,
is found to be identical to D. pictus in skeletal anatomy and similar to its congener in most
proportional measurements. D. ommata is distinguished from D. pictus by its dorsal color
pattern and differing clasper morphology. The genus and species of Diplobatis are rede-
fined, and the three subspecies are described. Finally, the four genera of Narcinidae
(Benthobatis, Diplobatis, Discopyge, and Narcine) are compared and found to be very
conservative anatomically. A phylogenetic analysis based on synapomorphic character states
shows Discopyge and Narcine to be the sister group to the other narcinids.
RESUMEN: Examinamos las caracteristicas morfol6gicas y anatomfa internal de la raya el6c-
trica del g6nero Diplobatis (Torpediniformes, Narcinidae) a fin de determinar el status
taxon6mico de sus varias formas. Todos los especimenes de la costa norte de Sudam6rica
(desde Colombia hasta Brasil) variaron notablemente en la mayoria de sus caracteristicas
morfol6gicas pero fueron id6nticos en estructura esqueletica. De acuerdo a coincidencia
en medidas proporcionales y a la falta de caracteres interns y externos distinguibles, la
especie D. altenai Boeseman 1963 se consider sin6nima a D. pictus Palmer 1950. Asim-
ismo, se verifica la sinonimia de D. guainachensis Martin 1957 con D. pictus por Bigelow
y Schroeder (1962). Se reconocen tres subespecies pertenecientes a D. pictus: D. pictus
pictus Palmer, D. pictus guamachensis Martin y D. pictus colombiensis nueva subespecie.
D. ommata, proveniente de las costas pacificas de M6xico y Am6rica Central, se consider
id6ntica a D. pictus en cuanto a anatomia del esqueleto y similar a su cong6nere en la
mayoria de sus medidas proporcionales. D. ommata se distingue por su patron dorsal de
color y diferente morfol6gia de los ganchos copulatorios clasperer"). Se redefine el g6nero
y las species de Diplobatis y se describe tres subespecies. Finalmente, los cuatro generos
de Narcinidae (Benthobatis, Diplobatis, Discopyge y Narcine) se comparan y se concluye
que son anat6micamente muy conservatives. El anilisis filogen6tico basado en caracteres
sinapom6rficos demuestra que Discopyge y Narcine son grupos hermanos de los otros
narcinidos.


'Research Assistant and 'Associate Professor, Department of Wildlife and Fisheries Sciences, Texas A&M University,
College Station, Texas 77843.

FECHHELM, J.D., AND J.D. MCEACHRAN. 1984. A REVISION OF THE ELECTRIC
RAY GENUS L WITH NOTES ON THE INTERRELATIONSHIPS OF NARCINIDAE (CHONDRI-
CHTHYES, TORPEDINIFORMES). BULL. FLORIDA STATE MUS., BIOL. SCI. 29(5):171-209.






























TABLE OF CONTENTS
INTRODUCTION .......................................................... 173
ACKNOWLEDGEMENTS .................................... ............. 175
METHODS AND MATERIALS ............................................ 175
RESULTS AND DISCUSSION ............................................ 176
TAXONOMIC CONCLUSIONS ............................................. 181
THE STATUS OF Diplobatis altenai BOESEMAN .................................. 181
THE STATUS OF Diplobatis pictus PALMER .................................... 181
THE STATUS OF Diplobatis ommata (JORDAN AND GILBERT) .................... 182
SYSTEMATIC ACCOUNTS .................................................. 183
Diplobatis BIGELOW AND SCHROEDER ........................................ 183
Diplobatis pictus PALMER ................ ................................. 188
Diplobatis pictus pictus PALMER .................. ................. .......... 190
Diplobatis pictus guamachensis MARTIN ......................................... 193
Diplobatis pictus colombiensis new subspecies ................................. 195
Diplobatis ommata (JORDAN AND GILBERT) .................................... 197
INTERRELATIONSHIPS WITHIN THE FAMILY NARCINIDAE ............... 200
LITERATURE CITED..................................................... 204
APPENDIX I: MATERIAL EXAMINED ............................................... 206






FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


INTRODUCTION

The systematic relationships within the Torpediniformes, as with many
other elasmobranch taxa, are largely unknown because of morphological
conservatism and lack of comprehensive anatomical studies. Most ana-
tomical studies of torpedinoids have been limited to a single species or
were undertaken as a minor part of comparative anatomical surveys of
elasmobranchs (Henle 1834; Richardson 1841; Gegenbaur 1865, 1872;
De Beer 1926; Daniel 1934; Holmgren 1940). While a few workers have
examined more than one genus (Haswell 1885; Howes 1890; Carman
1913; Holmgren 1941), the results of these studies were used to define
structural differences between torpedinoids and other elasmobranch taxa
and said nothing of the relationships within the electric rays. Recently,
Compagno (1973, 1977) combined these earlier studies with additional
examinations in order to determine interrelatonships of the Torpedini-
formes. His work suggests that Torpediniformes is a monophyletic group
derived from the guitarfishes (Rhinobatiformes) and distinguished by the
following derived characters: huge pectoral electric organs; no supraor-
bital crests on the neurocranium, anteriorly directed, fan- or antler-shaped
antorbital cartilages, extending to but not articulating with propterygia
of pectoral fins; and unique pectoral girdles, with a strut-supported pos-
terior tube-like extension holding a rhinobatoid-like articular surface for
the pectoral basals (Compagno 1977). Phylogenetically, the Torpedini-
formes are something of an enigma: while they exhibit some plesio-
morphic character states and are most often allied with primitive batoid
groups (Gegenbaur 1865; Daniel 1934; Bigelow and Schroeder 1953;
Compagno 1977), they possess several highly derived character states
that are not shared with any other orders of Batoidea (Heemstra and
Smith 1980). Torpediniformes are also the last batoid group to appear in
the fossil record (Romer 1966), and recent work on chromosome number
and genome size suggests a more advanced phylogenetic position for this
group (Donahue 1974; Stingo 1979).
Currently, four families of Torpediniformes are recognized (Compagno
1973): Hypnidae Gill 1862, a monotypic family; Torpedinidae Bonaparte
1838, with 1 genus and 14-17 species; Narkidae Fowler 1934, with 4
genera and 9 or 10 species; and Narcinidae Gill 1862, with 4 genera and
17 or 18 species.
The four genera of Narcinidae differ only slightly from each other.
Benthobatis Alcock 1898 is distinguished by an ovoid disc, very minute,
possibly non-functional eyes which may be entirely concealed by over-
lying integument, and no lateral fold on the tail. There are two species,
one from off the coast of India and one from the western Atlantic, both
found in deep water (up to 1000 m). Narcine Henle 1834 has a nearly


173






BULLETIN FLORIDA STATE MUSEUM


circular disc, normal, functional eyes, and a thin lateral fold on the tail.
There are 11 or 12 species: 8 from the Indian and southwestern Pacific
oceans, 2 or 3 from the eastern Pacific Ocean, and 1 from the western
Atlantic Ocean. All are usually found in shallow water. Discopyge Tschudi
1864 has a circular disc, a prominent lateral fold on the tail, and pelvic
fins joined across the base of the tail. The genus is monotypic and is
found off the coasts of Peru, Chile, Argentina, and southern Brazil. Di-
plobatis Bigelow and Schroeder 1948 has a subcircular disc with a mod-
erately convex anterior edge, normal functional eyes, nostrils subdivided
into two apertures, and a narrow lateral fold on the tail. Representatives
are found in the eastern Pacific Ocean from the Gulf of California to
Colombia and in the western Atlantic Ocean from Colombia to the mouth
of the Amazon River (Bigelow and Schroeder 1953).
Considerable confusion exists as to the number of distinct species within
Diplobatis. The genus was erected by Bigelow and Schroeder (1948) for
Discopyge ommata Jordan and Gilbert 1890 from the Gulf of California,
because of the unique structure of its nasal apertures. Diplobatis pictus
Palmer 1950 was described from the western Atlantic (Brazil to Guyana)
and was distinguished from D. ommata by disc shape, shape and location
of the pelvic fins, and dorsal coloration. Another species, Diplobatis gua-
machensis Martin 1957, was described from the coast of Venezuela. It
was distinguished from D. ommata and D. pictus by proportional mea-
surements, location of the lateral fold, and coloration. A fourth species,
Diplobatis altenai Boeseman 1963, was described from a single specimen
taken off the coast of Surinam. It was distinguished from its congeners
by the size of the eyes and spiracles, lack of papillae along the spiracular
margin, shape of the nasal curtain, location of the cloaca, size of the
dorsal and caudal fins, and coloration.
Bigelow and Schroeder (1962) examined 24 specimens of D. pictus
and noted considerable morphological variation, particularly in colora-
tion, but because of the small number of specimens examined, they simply
separated the specimens into freckled and non-freckled forms, based on
their dorsal patterns. In 1968, after examining additional specimens of
Diplobatis taken off the coasts of Venezuela and Brazil, Bigelow and
Schroeder stated that because of the extreme color variation observed
within D. pictus, and because proportional measurements of D. gua-
machensis fell within the ranges for D. pictus, D. guamachensis was a
junior synonym of D. pictus.
Palacio (1974) reported four specimens of what he identified as D.
pictus from the northwest shore of Colombia, but he gave no description
of them. Heemstra (pers. comm. to Palacio 1974) expressed the view that
both D. guamachensis and D. altenai were possibly juvenile forms of D.
pictus.
The examination of a large number of specimens of Diplobatis indi-


Vol. 29, No. 5







FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


cated greater morphological variation within the Atlantic forms than had
been previously recognized. This study was undertaken to assess the
extent of the morphological variation in order to determine the taxo-
nomic status of the Atlantic forms. Examinations of skeletal characteris-
tics along with morphometrics and coloration were used to determine
interrelationships within the genus. Finally, anatomical examinations of
the other genera of Narcinidae (Benthobatis, Discopyge and Narcine) were
used to elucidate interrelationships within the family.

ACKNOWLEDGEMENTS
We wish to thank S. Weitzman for providing work space at the USNM and the follow-
ing people for the loan of specimens: P.J. Whitehead (BMNH); G. Burgess (UF); R.J.
Lavenberg and T.A. Adamson (LACM); WL. Fink and K. Hartell (MCZ); S. Weitzman,
S. Jewett, and G. Van Dyke (USNM); and M. Boeseman and M. Hoogmod (RMNH). M.
Boeseman was extremely generous in supplying a large block of uncatalogued specimens
as well as information on the overall marine conditions off Surinam. R.G. Fechhelm, M.J.
McCoid, R.E. Matheson, and E.O. Murdy offered advice and encouragement during the
course of this study and reviewed the manuscript. Mark Engstrom provided statistical
advice; photographs of the specimens were made by Ephraim Seidman. This manuscript
is based on a thesis submitted by the first author in partial fulfillment of the requirements
of the M.S. Degree in Wildlife and Fisheries Sciences, Texas A&M University. This study
was supported in part by National Science Foundation Grant DEB 78-11217 to the sec-
ond author.

METHODS AND MATERIALS
Specimens examined in this study are listed in Appendix I and were borrowed from
the following institutions: British Museum (Natural History) (BMNH), London; Florida
State Museum (UF), Gainesville; Los Angeles County Museum of Natural History (LACM),
Los Angeles; Museum of Comparative Zoology (MCZ), Cambridge; National Museum of
Natural History (USNM), Washington, D.C.; Rijksmuseum van Natuurlijke Historie
(RMNH), Leiden; and the Texas Cooperative Wildlife Collection (TCWC), College Sta-
tion.
A total of 274 specimens of Diplobatis were examined; 45 external measurements as
well as eight morphological characters were recorded for each specimen. Methods of Big-
elow and Schroeder (1953) were followed in making external measurements. Characters
that have proved valuable in distinguishing and grouping other taxa of batoids, i.e. neu-
rocranium, hyobranchial skeleton, scapulocoracoid, pelvic girdle, and claspers, were ex-
amined for all species. Anatomical descriptions are based on dissected specimens: com-
plete dissections, involving removal of the neurocranium, jaws, hyobranchial skeleton,
scapulocoracoid, and pelvic girdle, were performed on at least one specimen of each form
examined. To facilitate dissection of some of the smaller specimens, the cartilage was first
stained with methylene blue following the methods of Van Wijhe (1902). Clasper dissec-
tions were not possible because of their small size (less than 20 mm) and the fragile nature
of the cartilage. Terminology for clasper morphology is as follows: all cartilages on the
dorsal, lateral, and ventral aspects of the clasper are referred to as the dorsal terminal,
lateral terminal, and ventral terminal cartilages, respectively. Other terms are from Hul-
ley (1972). The use of these terms does not imply that these structures in torpedinoids are
homologous to those in skates (Rajoidei). Terminology for all other skeletal structures is
from Holmgren (1940), Compagno (1973, 1977), and McEachran and Compagno (1979).
Radiographs were examined in order to count vertebrae and pelvic radials, as well as


175







BULLETIN FLORIDA STATE MUSEUM


to confirm the dissection. The vertebral counts represent the total number of vertebrae,
as differentiation between trunk and precaudal vertebrae could not be made. In the only
case where dissection was not possible (i.e. Discopyge tschudii), the drawings were con-
structed from radiographs.
Programs from the Statistical Analysis System (SAS: Helwig and Council 1979) were
used to perform Student's t-tests as well as to compute the mean, range, standard devia-
tion, and standard error of the mean for variables separated into various subsets of the
data. In these analyses, external measurements were expressed as percent of total length
to account for differences in size.
Specimens separated into various groups based on geographical distribution were ex-
amined in order to determine if there were any significant differences between two groups
using Student's t-tests. For those that showed a significant difference, levels of significance
are given in the text.
Multivariate analyses were performed using the Cluster and Principal Component
Analyses of the Numerical Taxonomy System (NT-SYS; Rohlf and Kispaugh 1972). Of the
45 variables measured for each specimen, only those that could be measured with good
accuracy (n = 21) were used. Damaged specimens on which it was impossible to take com-
plete measurements were not used in the multivariate analyses. Data from the specimens
were first standardized using an arcsine transformation. In the analyses, no assumptions
were made regarding the taxonomic status of any specimen nor were any a priori groups
formed.
Presumably owing to the extreme morphometric variation exhibited by the specimens,
these multivariate tests gave inconclusive results in that they failed to separate the speci-
mens into any discrete groups. Since none of the results of this study were based solely
on morphometric differences, the results of these tests are not presented.

RESULTS AND DISCUSSION

The Atlantic forms of Diplobatis can be divided into three geographi-
cally distinct color morphs. Group A is found from the mouth of the
Amazon River to Trinidad (Fig. 1) and is characterized by a polytypic
color pattern (Fig. 2) ranging from tan with no markings (morph #1) to
tan with a few indistinct brown or white spots or both (morph #2) (the
non-freckled type of Bigelow and Schroeder, 1962); tan with well de-
fined, fairly symmetrical brown spots (morph #3) (as described for D.
altenai); tan with well defined, fairly symmetrical brown and white spots
(morph #4) (as described for the holotype of D. pictus); and tan with
numerous, asymmetrical, very small brown and white spots (morph #5).
While all specimens examined from this region can be roughly classified
under one of the above morphs, it should be stressed that a complete
gradation exists between all color patterns. The polytypic nature of this
group is also evidenced by a mature female (157 mm TL) taken off Suri-
nam, which contained four nearly full term young. While the female has
a non-freckled dorsal color pattern (morph #2), two of the embryos have
very distinct markings similar to the holotype of D. pictus (morph #4),
while the remaining two exhibit the color pattern of D. altenai (morph
#3).
Group B is found from Trinidad to just west of the Gulf of Venezuela


Vol. 29, No. 5







FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


Figure 1. Map of northern South America showing the distribution of the Atlantic
forms of Diplobatis examined in this study. Some locations represent multiple lots.


0 Pi
Vf /
^;~~'*y


Figure 2. Dorsal color patterns found in Group A: (a) morph #1, USNM 226775,
female, 162 mm TL; (b) morph #2, UF 29894, female, 138 mm TL; (c) morph #3, USNM
186422, male, 133 mm TL; (d) morph #4, TCWC 1905.1, female, 101 mm TL; (e) morph
#5, BMNH 1961.8.31, female, 145 mm TL.







BULLETIN FLORIDA STATE MUSEUM


(Fig. 1) and is characterized by the dorsal color pattern described for D.
guamachensis (Fig. 3a), i.e. golden tan with brown bands running lon-
gitudinally on the edges of the disc and the pelvic fins and transversely
on the body and tail. The thickness of the bands varies but never exceeds
0.5 times the diameter of the eye, and while indistinct in some speci-
mens, the bands are always arranged in the characteristic pattern.
Group C is found off the coast of northwestern Colombia (Fig. 1), and
its dorsal color pattern (Fig. 3b) is golden tan with brown spots of various
sizes. The spots also vary in number and at times are somewhat symmet-
rical.
The three groups varied little in body shape and morphometrics (Table
1). All characteristics examined (including both proportional measure-
ments and morphological features) showed broad overlap among the three
groups. However Group B has a somewhat shorter snout length (pre-
ocular and prebuccal) than either Group A (P<0.01) or Group C (P<0.01)
(Fig. 4a,b), and Group C has a relatively narrower disc than either Group
A (P<0.01) or Group B (P<0.01) (Fig. 4c). External clasper morphology
of all three groups is identical, as is the internal skeletal structure of the
neurocranium, hyobranchial skeleton, scapulocoracoid, and pelvic girdle.
The areas inhabited by the three groups are contiguous but do show
some substrate and salinity differences. Within the range of Group A the
substrate is mainly soft mud with virtually no coral reef formation; salin-
ity levels fluctuate dramatically from the large amounts of freshwater
runoff from the numerous river systems, in particular the Amazon and
Orinoco river systems (Mitchell 1959; Lowe-McConnell 1962; Bullis and
Thompson 1965; U.S. Naval Oceanographic Office 1965; Gines and Cer-
vigon 1968; Gorshkov 1978). The fluvial outflow also exerts a noticeable
influence on the coastal morphology of the region in the form of exten-
sive tidal mud flats in some areas (Lowe-McConnell 1962). The substrate
in the range of Group B is mostly hard sand with extensive coral reef
development in some areas; there is little fluctuation in salinity, and the
coastline is very eroded and embayed owing to the action of strong tidal
currents (Bullis and Thompson 1956; U.S. Naval Oceanographic Office
1965; Gorshkov 1978). The area inhabited by Group C shows similarities
to both of the preceding areas: the substrate is mostly hard sand, but
there are areas of soft mud, and while there is coral reef development, it
is much less than in the preceding region (Bullis and Thompson 1965;
U.S. Naval Oceanographic Office 1965; Gorshkov 1978).
The Atlantic forms of Diplobatis and the Pacific D. ommata differ mainly
in coloration and clasper structure. The dorsal coloration of D. ommata
is strikingly distinct from its congeners and consists of a brown back-
ground irregularly mottled and spotted with lighter and darker markings
which are more pronounced on the disc and absent on the snout. Most


Vol. 29, No. 5







FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


Figure 3. Dorsal color patterns of: (a) Group B, UF 19886, male, 128 mm TL; and (b)
Group C, USNM 226773, male, 129.5 mm TL.

noticeable is the large blackish and yellowish ocellated spot in the center
of the disc. Both Atlantic and Pacific specimens of Diplobatis have very
short and stout claspers, but the claspers of the Atlantic forms are con-
stricted at mid-length and taper distally to a blunt point, while the clas-
per of D. ommata is stout its entire length (not constricted at mid-length),
with a broadly rounded distal tip. The ventro-lateral slit (= pseudosi-
phon?) of the Atlantic forms extends from the lateral edge onto the ven-
tral surface, while that of D. ommata is confined to the lateral edge. In
the Atlantic forms, the dorsal terminal cartilage does not form the dorsal
wall of the clasper groove, but in D. ommata the dorsal terminal cartilage









98 Group A

38 Group B

16 : I. Group C
I I L I I I I I
.06 .07 .08 .09 .10 .11 .12 .13 .14


98 Group A

38 r I Group B

16 i Group C

.09 .10 .11 .12 .13 .14 .15 .16


98 I Group A

38 i aI I Group B

16 i I Group C

.38 .40 .42 44 .46 .48 .50 .52 .54 .56




152 D. pictus

26 D. ommata

.10 .11 .12 .13 .14 .15 16 .17 .18


152 I I D. pictus

26 iM D. ommata

.30 .40 .50 .60 .70 .80


Figure 4. Variation in (a), preocular snout length; (b), prebuccal snout length; and (c)
disc width among the Atlantic forms of Diplobatis (Group A, Group B, and Group C).
Variation in (d), length of dorsal lobe of caudal fin; and (e), interorbital distance between
D. pictus and D. ommata. In each diagram the horizontal line represents the mean, the
open rectangle equals one standard deviation and the closed rectangle represents two
standard errors of the mean. Numbers on the vertical scale are percent of total length;
the number to the left of each diagram is the sample size.






FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


is distally folded 180 to overlie the lateral terminal cartilage, thereby
forming the dorsal wall of the clasper groove.
While the two groups are similar in proportional measurements (Table
2), D. ommata has a shorter dorsal lobe of the caudal fin (P<0.01) which
results in a more rounded caudal fin when compared to the Atlantic forms,
which have a more triangular caudal fin (Fig. 4d). Also, D. ommata has a
slightly greater interorbital distance than the Atlantic forms (P<0.01) (Fig.
4e).

TAXONOMIC CONCLUSIONS

THE STATUS OF Diplobatis altenai BOESEMAN 1963

Morphological comparisons of the holotype of D. altenai with speci-
mens of D. pictus failed to reveal any concrete morphological differ-
ences. The characters used to differentiate D. altenai from D. pictus, i.e.
vent before half total length, smaller eyes and orbits, lack of papillae
along the spiracular margins, smooth free edge of the nasal curtain, smaller
gill openings, lower and shorter dorsal fins, and larger caudal fin (Boese-
man 1963), are also found in many specimens of D. pictus. The dorsal
coloration of D. altenai (light brownish with numerous dark spots of var-
ious size) does not represent a distinct type but rather is part of a contin-
uum that ranges in Group A from specimens with no markings to those
with very ornate patterns. Also, proportional measurements of the holo-
type ofD. altenai fall well within the ranges ofD. pictus examined (Table
3), and the clasper morphology of D. altenai is identical with that of D.
pictus. The lack of differences between these two species was previously
noted by Gines and Cervigon (1968). After examining specimens of D.
pictus taken off the coasts of the Guianas and Surinam, they stated that
they did not identify any specimens of D. altenai (which had been de-
scribed from this area) because of their inability to differentiate between
D. pictus and D. altenai. Heemstra (pers. comm. to Palacio 1974) also
noted the similarities between D. altenai and D. pictus and stated that
the two species were possibly synonymous. As no morphological or mor-
phometrical differences are discernible between the two species, we
consider D. altenai a junior synonym of D. pictus.

THE STATUS OF Diplobatis pictus PALMER 1950

The various Atlantic forms of Diplobatis are very similar with the ex-
ception of their differing dorsal color patterns, which are possibly related
to their benthic existence. Living in close association with the substrate,






BULLETIN FLORIDA STATE MUSEUM


it is likely that the various types of sediment found in the three areas
could result in differing selection pressures which may enhance the de-
velopment of the various color patterns. If the selection pressures remain
relatively constant, genetic reinforcement of the differences could occur
(Barlow 1961). The parapatric and allopatric distributions of the three
groups suggests a possible lack of or reduction in gene flow between the
populations, and enforces the idea that the between-group color differ-
ences are at least partially genetic. While the vagility of Diplobatis is not
known, there appear to be no absolute physical or biotic barriers that
would prevent movement of individuals from one area to another. This,
along with the absence of any differences in both internal structure and
clasper morphology of the three groups, suggests that the groups have
not attained levels of specific distinction. The similarity of the clasper
morphology among the specimens is even more striking when we con-
sider the differentiation this structure has undergone between the Atlan-
tic Diplobatis and the Pacific D. ommata.
Therefore, while the three Atlantic groups of Diplobatis do not appear
distinct enough to warrant recognition as separate species, they do seem
sufficiently heterogeneous to justify subspecific designation. D. pictus
pictus (= Group A) consists of specimens formerly identified as D. pictus
and D. altenai; D. pictus guamachensis (= Group B) consists of speci-
mens formerly identified as D. guamachensis; and D. pictus colombiensis
subs. nov. (= Group C) which is described herein.

THE STATUS OF Diplobatis ommata (JORDAN AND GILBERT 1890)
While D. ommata is similar to D. pictus, the distinctions between the
two warrant their continued recognition as separate species. The fact that
these two species are identical in internal anatomy and similar in propor-
tional measurements is not surprising when one considers the conserva-
tive nature of electric rays. Within the genus Narcine few, if any, anatom-
ical or proportional differences exist between the species N. brasiliensis,
N. entemedor, and N. vermiculatus (pers. obs.). In fact, there are very
few anatomical differences between the four genera of Narcinidae. Con-
cerning clasper structure, it is important to note that the other three
genera (Narcine, Benthobatis, and Discopyge) are virtually identical in
their external clasper morphology. This emphasizes the importance of
the morphological differentiation this structure has undergone between
D. pictus and D. ommata. (While the claspers were not examined inter-
nally [as previously discussed], it is reasonable to assume that the gross
differences in external morphology reflect differing internal anatomy.)
Also, there is absolutely no intergradation of either clasper structure or
dorsal color pattern between the two species.


Vol. 29, No. 5







FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


SYSTEMATIC ACCOUNTS

Diplobatis BIGELOW AND SCHROEDER
Diplobatis Bigelow and Schroeder 1948:562-565. Type species: Discopyge ommata Jor-
dan and Gilbert 1890; by monotypy.
DIAGNOSIS.-Diplobatis is distinguished from all other genera of
Narcinidae by nostrils that are subdivided into two apertures and by
clasper morphology. Other important characters are as follows: disc sub-
circular, slightly broader than long to slightly longer than broad; anterior
edge of disc slightly to moderately convex; pelvic fins not joined across
base of tail; claspers not continuous with inner edge of pelvic fin; mod-
erately stout tail with two dorsal fins and well developed, subtriangular
caudal fin; narrow lateral fold on tail; snout to cloaca length 43-65% of
total length. Diplobatis is also the smallest genus of Torpediniformes,
ranging from 50 to 60 mm TL at birth to a maximum size of 250 mm TL.
INTERNAL DESCRIPTION. -Neurocranium (Fig. 5) has a very long
and broad rostrum, its length 40-60% of total cranial length; antorbital
cartilages variable in shape and extent of branching, joining indistinctly
with tip of rostrum; precerebral fossa rectangular, occupying nearly all of
rostrum; basonasal fenestrae sub-rectangular, length approximately 30%
precerebral fossa length; frontoparietal fenestrae slightly smaller than ba-
sonasal fenestra and elliptical in shape; area between antorbital cartilages
and rostrum interlaced with strong bands of fibrous tissue; condyles for
antorbital cartilages triangular, located on lateral surface of nasal capsule;
nasal capsule very variable in extent of cartilaginous development. An-
terior foramen for preorbital canal very small and located on dorsal as-
pect of nasal capsule, near junction of nasal capsule and rostral base;
posterior foramen for preorbital canal extremely small and located dor-
solaterally at junction of nasal capsule and orbit; interorbital region broad;
anterior fontanelle irregular in shape, narrowing posteriorly; foramen for
orbitonasal canal just ventral to posterior foramen of preorbital canal;
optic nerve foramen of moderate size and situated anterior to midline of
orbit; occulomotor nerve foramen very small and located posterior to
optic nerve foramen and dorsal to optic pedicle; orbital fissure very large,
situated on posterior aspect of orbit, anterior to foramen for hyomandi-
bular branch of facial nerve; glossopharyngeal nerve foramen located
posterodorsally to hyomandibular facet; vagus nerve foramen located
posterodorsally to glossopharyngeal nerve foramen. Basal plate ex-
tremely narrow, particularly at level of orbits.
Hyomandibula (Fig. 6a) very stout and anterolaterally oriented to
cranium; jaws stout, lower jaw much longer than upper jaw and with
strong attachment to hyomandibula; labial cartilages at corners of jaw,


1984


183







BULLETIN FLORIDA STATE MUSEUM


1 cm


Sff pstc t of





Sprec onc os
aoc I /
antc 8 | BII I x
nc hf


Figure 5. Neurocranium of Diplobatis (TCWC 1900.1). (a) dorsal view; (b) ventral
view; (c) partial dorsal view showing antorbital cartilages; (d) lateral view: af, anterior
fontanelle, antc, antorbital cartilages; aoc, antorbital condyle; bf, basonasal fenestrae; end,
endolymphatic foramen; ff, frontoparietal fenestrae; hf, hyomandibular facet; ic, internal
carotid artery foramen; nc, nasal capsule; of, orbital fissure; one, orbital nasal canal; or,
orbit; os, optic stalk; ot, otic capsule; peri, perilymphatic foramen; pf, precerebral fossa;
postc, postorbital canal foramen; prec, preorbital canal foramen; ro, rostrum; II, optic
nerve foramen; III, oculomotor nerve foramen; VII, hyomandibular branch of facial nerve
foramen; IX, glossopharyngeal nerve foramen; X, vagus nerve foramen. Dashed lines in-
dicate areas of indistinct calcification.

not calcified at midsection. Ceratohyal (Fig. 6b) very long and slender,
attached to hyomandibula by weak ligamentous connection; ventral
pseudohyoid flattened anteroposteriorly, its lateral end articulating with
dorsal pseudohyoid; first hypobranchials dorsal to medial end of cerato-
hyal and ventral to first ceratobranchial, second hypobranchials very large
and rectangular in shape; ceratobranchials well developed, 1 through 3


Vol. 29, No. 5







FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


hm
"\ \"":








1cm



LO--bh?
hb ch

vph

dph




cb




Figure 6. Jaws and hyobranchial skeleton of Diplobatis (TCWC 1900.1). (a) ventral
view of jaws and hyomandibula showing placement in relation to hyobranchial skeleton;
(b) ventral view of hyobranchial skeleton: bh, basihyod; cb, ceratobranchial; ch, cerato-
hyal; dph, dorsal pseudohyoid; hb, hypobranchial; hm, hyomandibula; Ic, labial cartilage;
me, Meckel's cartilage (lower jaw); pq, platoquadrate (upper jaw); vph, ventral pseudoh-
yoid.






BULLETIN FLORIDA STATE MUSEUM


articulating with second hypobranchial; ceratobranchials 4 and 5 articu-
lating with basibranchial copula; fifth ceratobranchials somewhat re-
duced and articulating distally with anterior ascending process of scapu-
locoracoid; basibranchial copula triangular with pronounced posterior
projection. In addition to these elements, a pair of moderately large,
rectangular-shaped cartilages are located ventral to the cranium. The
identity of these cartilages is unclear. Compagno (1977) tentatively iden-
tified them as basihyoids, which appears incorrect as these elements are
not associated with the hyobranchial skeleton, but lie directly below the
cranium and dorsal to the esophagus.
Scapulocoracoid (Fig. 7a, b) with sub-rectangular lateral face; scapular
process inclined posteromedially; posterior corner of scapulocoracoid ex-
tends as a tube-like structure which holds articular surfaces for pectoral
basals; anteroventral corner extends below vertebral column as coracoid;
anterior fenestrae of moderate size, its height approximately 50% of the
total height and its length approximately 30% of the total length of the
scapulocoracoid. There are four nerve foramina; postdorsal nerve fora-
men and postventral nerve foramen are located on either side of both
the procondyle and the mesocondyle.
Pelvic girdle (Fig. 7c) consists of a relatively short puboischiadic bar
with lateral extremes curved dorsally; prepelvic processes well devel-
oped, though lightly calcified anteriorly, their length nearly equal to the
width of the girdle; iliac processes stout, slightly curved and directed
posterolaterally. Three obturator foramina are located at the junction of
the iliac and prepelvic regions.
REMARKS.-The subdivided nostrils of this genus set it apart not only
from other Narcinidae but from all batoids as well. This condition was
originally described by Bigelow and Schroeder (1953) as ". . nostril
subdivided about midway of its length into two separate apertures by a
cross bridge of stiff tissue," and is illustrated as such in Bigelow and
Schroeder (1953) and Palmer (1950). As Tucker (1954) pointed out, this
description is not wholly accurate, for rather than being divided by a
bridge of tissue, the division of the nasal apertures is the result of fusion
between the dorsal side of the nasal curtain (anterior nasal flaps) and the
ventral side of the posterior nasal flap. This connection can be broken if
the nasal curtain is forceably lifted. Once the two are separated, it is
difficult to determine if the connection ever existed. For this reason,
Tucker (1954) felt that this character was of questionable use taxonomi-
cally. We disagree with Tucker (1954) and consider this character very
useful, for in none of the specimens of Diplobatis we examined was this
connection broken on both sides of the nasal curtain.
Morphometrics are of little value in the systematics of Diplobatis ow-
ing to the great amount of morphological variability. Every characteristic


Vol. 29, No. 5







FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


1A m


/ !- sy



pdf

i PVf MtC

VIc









Figure 7. Scapulocoracoid and pelvic girdle of Diplobatis (TCWC 1900.1). (a) lateral
view of scapulocoracoid; (b) dorsal view of scapulocoracoid and vertebral column; (c) dor-
sal view of pelvic girdle: af, anterior fontanelle; co, coracoid; msc, mesocondyle; mtc,
metacondyle; obf, obturator foramina; pdf, postdorsal nerve foramina; prc, precondyle;
prp, prepelvic processes; ps, puboischiadic bar; pvf, postventral nerve foramina; sp, sca-
pular process; su, suprascapula; sy, synarcual; vc, vertebral column.
examined, including all measurements recorded, illustrated this. Many
specimens appear very wrinkled, with folds of loose skin all over the
body, particularly on the ventral side, making measurements difficult.
We have also examined several deformed specimens (n = 17) of Diploba-
tis. In these cases, the cloaca and gill slits are stretched into circular
openings, the mouth protrudes, the nasal curtain is pulled anteriorly,
the spiracles are pulled open making the papillae along their margins
barely evident, the pelvic fins are pulled very close to the body, the back
is humped, and in most cases the skin on the disc is torn and shredded;
the overall appearance of these specimens gives one the impression that
the skin has somehow shrunk. The reasons for this condition are un-
known. Improper preservation techniques could be the cause, but we
examined one single lot that contained both deformed and normal spec-
imens. Two species of Torpedo, described as having "teratological de-
formities," were discussed by Palmer and Wheeler (1958). Their terato-
logical specimens are described as showing many of the features we noted






188 BULLETIN FLORIDA STATE MUSEUM Vol. 29, No. 5

in the deformed specimens, i.e. humped back, pelvic fins pulled ven-
trally, and small nasal flap. While it seems somewhat unlikely that all the
deformed specimens we examined exhibited teratological abnormalities,
this possibility should not be ignored.
The measurements of these deformed specimens were not used in this
study in any way. They are of importance, however, for they emphasize
the fact that because of the variable morphological nature of electric rays,
care should be taken with all taxa of Torpediniformes before basing tax-
onomic conclusions solely on morphometrics.

Diplobatis pictus PALMER
Diplobatis pictus Palmer 1950: 480-484.
Diplobatis guamachensis Martin 1957: 1-3.
Diplobatis altenai Boeseman 1963: 296-299.
DIAGNOSIS. -Diplobatis pictus is distinguished by its dorsal colora-
tion, clasper morphology and range. Other useful characteristics are a
relatively narrow interorbital distance; a subrectangular caudal fin usu-
ally with a distinct upper corner; and a very small total length, not ex-
ceeding 200 mm.
DESCRIPTION.-External morphology (Figs. 2, 3): Proportional mea-
surements are given in Table 1. Measurements reported here represent
the mean value, followed by the minimum and maximum values in pa-
rentheses. Disc round- to spade-shaped, 0.99 (0.82-1.21) times as broad
as long; anterior margin of disc evenly rounded to slightly angular; axis
of greatest width 68.2% (55.1-82.9%) of distance from tip of snout to axil
of pectoral fins. Pelvic fins originate at or anteroventrally to axil of pec-
toral fins; anterior margin of pelvic fin short, 0.36 (0.27-0.49) times breadth
of pelvic fins and 0.5 times or less length of posterior margin of pelvic
fin; angle of anterior margin of pelvic fin from 450 to 900 to long axis of
body; posterior margin of pelvic fin straight to slightly convex when fully
spread; pelvic fins usually broadly rounded but at times with distinct
lateral points; inner margins of pelvic fins free from or connected to sides
of tail for a short distance. Tail moderately stout, convex dorsally, and
slightly flattened ventrally, its width midway between posterior tips of
pelvic fins and distal tip 0.49 (0.30-0.75) times as wide as interorbital
distance; tail with a narrow lateral fold along lateral surfaces, originating
from opposite midpoint of first dorsal fin to origin of second dorsal fin
and ending at origin of, or slightly posterior to origin of caudal fin; length
of tail from center of cloaca to distal tip to 0.91 (0.79-1.11) times distance
from tip of snout to center of cloaca. Two dorsal fins on tail; upper corner
of both dorsal fins from broadly rounded to acute; first dorsal fin located
from entirely over to entirely posterior to pelvic fins; interspace between
first and second dorsals 0.64 (0.41-0.98) times as long as base of first
dorsal fin; second dorsal fin usually slightly higher than first; distance







FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


between second dorsal fin and caudal fin 0.73 (0.41-1.28) times as long
as base of second dorsal fin. Caudal fin sub-triangular, with distinct up-
per corner; base of caudal fin 0.86 (0.65-1.10) times as long, and its
height 0.92 (0.67-1.17) times as great as dorsal lobe of caudal fin.
Preocular length 2.32 (1.53-3.41) times as long as orbit-spiracle dis-
tance; preoral length 2.07 (1.47-2.70) times internarial distance; eyes
well developed, diameter of orbit equal to or slightly less than interor-
bital distance in smaller specimens (< 130 mm), and approximately 0.5
times interorbital distance in larger specimens (> 130 mm); orbit length
greater than spiracle length in most cases; spiracle ringed with 5-10 low,
rounded papillae papillaee barely evident or absent in a few cases). Nasal
curtain very variable in size, much wider than long, free edge of nasal
curtain either smooth or slightly crenulate and often projecting slightly
at midline; nasal curtain often extending posteriorly to overlap upper and
reaching lower jaw when mouth is fully closed; mouth approximately as
wide as nasal curtain. Teeth in both jaws in a triangular patch, arranged
in quincunx, about 14-16 rows counting inward at center of jaw, outer-
most row with one or two teeth and each succeeding row increasing,
resulting in 16-20 teeth in innermost rows; anterior few teeth usually
without cusps, the succeeding teeth with small triangular cusps which
become increasingly long and narrow on the posterior teeth, all cusps
pointing inward; teeth usually concealed when mouth is closed, how-
ever, two to seven rows of teeth may be exposed on the lower jaw even
when mouth is closed.
The clasper of D. pictus (Fig. 8) is very short and stout, not continuous
1 cm









dt
cg

vis dd It
vt

Figure 8. External clasper morphology ofDiplobatis pictus (USNM 226775). (a) ventral
view; (b) dorsal view: ap, apopyle; cg. clasper groove; dd, dermal denticles; dt, dorsal
terminal cartilage; It, lateral terminal cartilage; vls, ventrolateral slit; vt, ventral terminal
cartilage.


189







BULLETIN FLORIDA STATE MUSEUM


with inner edge of pelvic fin and extending posterior to or just beyond
posterior tip of pelvic fin; clasper constricted approximately at midpoint,
widening distally, then tapering to a blunt point; ventrolateral slit
(= pseudosiphon?) extending from lateral edge well onto ventral surface;
dorsal surface with dermal denticles on dorsal terminal cartilage; dorsal
terminal cartilage not forming dorsal wall of clasper groove.
The dorsal color pattern of D. pictus is very variable, with individuals
ranging from tan with no markings to tan with either small brown or
white spots or both; golden tan with wavy brown bands; and golden tan
with brown spots of various size. Detailed descriptions of the coloration
of all forms are included in the subspecies descriptions.
RANGE.-D. pictus is known only in the Atlantic Ocean, from the
coasts of Brazil (north of the Amazon River basin), French Guiana, Suri-
nam, Guyana, and Colombia (Fig. 1). Most specimens are taken in depths
of less than 40 m, although a few specimens have been taken as deep as
183 m.


Diplobatis pictus pictus PALMER 1950
FIGURE 9

MATERIAL EXAMINED.-182 specimens, listed in Appendix I. Pro-
portional measurements are given in Table 1.
DIAGNOSIS.-Diplobatis pictus pictus is distinguished from the other
subspecies of Diplobatis by its dorsal color pattern and range.
DESCRIPTION.--The dorsal color pattern of this subspecies is ex-
tremely variable and consists of a tan or light brown background which
is usually overlayed with a variety of brown or white spots, or both. Spec-
imens can be divided into five somewhat arbitrary color morphs (Fig. 2).
Morph #1: tan with no markings except for a few dark scratch-like marks
on some specimens. Morph #2: tan with two to six small white spots, 1/
4 the size of the orbits, irregularly scattered on the disc, or a few larger,
indistinct and irregularly scattered dark blotches, or both. Morph #3:
tan with fairly symmetrical dark brown spots, ranging from 1/4 to 1/2 the
size of the orbits, well defined and smaller on the central part of the disc
and increasing to one to four times the size of the orbits towards the
margins of the disc and pelvic fins; usually with a dark blotch in front of
and/or aside each dorsal fin and one or more dark spots on the dorsal and
caudal fins. Morph #4: tan with dark brown spots, 1/4 to 1/2 the size of
the orbits and larger brown blotches arranged fairly symmetrically; also
four to eight (usually five) moderately sized white spots symmetrically
arranged on the central part of the disc and usually four or more white


Vol. 29, No. 5




















I'


C. d.



Figure 9. Diplobatis pictus pictus: (a, b) UF 19882, mature male, 134.8 mm TL, dorsal
and ventral views; (c, d) UF 29893, female, 102.7 mm TL, dorsal and ventral views.







BULLETIN FLORIDA STATE MUSEUM


Figure 10. Coastline of northeastern South America showing the distribution of the
five color morphs observed within Diplobatis pictus pictus. Sample sizes are indicated.
Refer to Fig. 2 for photographs of the various color morphs.

spots, two each at the axils of the pectoral fins and on the pelvic fins;
both the white spots and the dark blotches often appear ringed by a
series of very small brown spots; there is usually a dark blotch in front of
and/or aside each dorsal fin and several dark spots may be present on the
dorsal and caudal fins. Morph #5: tan with numerous small to very tiny
brown and white spots densely scattered over the surface, at times sym-
metrical, and usually larger on the margins of the disc and pelvic fins; at
times the brown spots form indistinct circles; there is usually a dark blotch
present in front of and/or aside each dorsal fin and several dark spots may
be present on the dorsal and caudal fins. In all morphs, two dark, cres-
cent-shaped blotches may be present surrounding the anterior edge of
the orbits, and anterior to this (i.e. on the tip of the snout) there may be
no coloration at all. The ventral surface of all morphs is white to cream
colored with no markings.
RANGE.-D. p. pictus is found off Brazil from the mouth of the Ama-
zon River northward along the coasts of French Guiana, Surinam, Guy-
ana, and southeastern Venezuela to the Orinoco River delta and Trini-
dad. It is most common on muddy or sand bottoms and ranges in depth
from 2 to 130 m.
REMARKS.--The five color morphs of D. p. pictus are distributed in a


Vol. 29, No. 5







FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


southeast to northwest dine (Fig. 10). Specimens with a few or no mark-
ings (morphs #1 and #2) are more prevalent in the southern part of the
range while specimens with a variety of white and brown markings (morphs
#4 and #5) are more common in the northern part of the range. Inter-
mediate types (morph #3) occur throughout the entire area. This mor-
phocline again suggests that some extrinsic factor such as sediment com-
position or salinity influences the development of the differing dorsal
color patterns. Most noticeable in this case is the fact that specimens in
morph #1, i.e. those with no distinct markings, are most common off the
Amazon River delta, a region of very turbid waters and muddy, silt-cov-
ered bottoms. The remaining morphs do not appear to be directly re-
lated to any particular ecological conditions. Again, more information on
the natural history of these fish is necessary before further conclusions
can be reached.

Diplobatis pictus guamachensis MARTIN 1957
FIGURE 11

MATERIAL EXAMINED.-51 specimens, listed in Appendix I. Propor-
tional measurements are given in Table 1.
DIAGNOSIS.-Diplobatis pictus guamachensis is distinguished from
the other subspecies of D. pictus by its dorsal color pattern and range.
In addition to this, D. p. guamachensis has a relatively short snout length
(preocular and prebuccal).
DESCRIPTION. -The dorsal color pattern of D. p. guamachensis con-
sists of a tan to golden-tan background with darker brown wavy bands
running longitudinally on the edges of the disc and pelvic fins and trans-
versely on the tail, and ranging in thickness from very thin to approxi-
mately 1/2 the diameter of the orbits. There is an elongated U-shaped
brown band located just posterior to the eyes and often continuing ante-
riorly to form dark, crescent-shaped areas in front of the orbits, usually
appearing as an M- or Y-shaped design. In some specimens the bands
form indistinct circles, particularly on the tail. There are usually a few to
several dark brown spots on the dorsal and caudal fins. The ventral sur-
face color is white to cream with no markings.
RANGE.-D. p. guamachensis is distributed from just west of Trinidad
to slightly west of the Gulf of Venezuela (eastern Colombia) (Fig. 1).
However, this species is most common in the area near the Gulf of Ven-
ezuela (69W to 73W long). It ranges in depth from 30 m to 183 m.
REMARKS.-D. p. guamachensis exhibits little of the variation seen in
the preceding subspecies. The dorsal color pattern of this subspecies is
very distinctive, and although some specimens appear faded or faint, the
distinctive markings are always visible.


1984


193

















a. b. ""1


















C. d.


Figure 11. Diplobatis pictus guamachensis: (a, b) UF 29886, male, 128 mm TL, dorsal
and ventral views; (c, d) USNM 226777, female, 120 mm TL, dorsal and ventral views.







FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


While this species is known from Trinidad to eastern Colombia, only
a few specimens have been recorded from eastern Venezuela (Fig. 1; see
also Cervigon 1966). The Cariaco Trench, situated between Trinidad and
the Gulf of Venezuela (Fig. 1), ranges from 900 m to 1400 m in depth.
As these benthic fish have never been taken deeper than 183 m, this
area could serve as a partial barrier to this subspecies' eastward migra-
tion. Those specimens taken east of the Cariaco Trench are possibly
stragglers from the main population, although this cannot be verified
without additional sampling.
D. guamachensis Martin 1957, described from the area and later syn-
onymized with D. pictus (Bigelow and Schroeder 1962), represents the
type of this subspecies, hence the subspecific designation of guamach-
ensis.

Diplobatis pictus colombiensis new subspecies
FIGURE 12

HOLOTYPE.-USNM 232494, female, 149.2 mm TL, 951' N. lat.,
76o09' W long., off northwestern Columbia, at a depth of 98 m, 42 XI
68.
PARATYPES.-USNM 232929, male, 129.5 mm TL; male, 134.7 mm
TL, 9051' N. lat., 7609' W long., off northwestern Colombia, at a depth
of 98 m, 24 X 68.
MATERIAL EXAMINED.--16 specimens, listed in Appendix I. Propor-
tional measurements are given in Table 1.
DIAGNOSIS.-Diplobatis pictus colombiensis is distinguished from the
other subspecies of D. pictus by its dorsal color pattern and range. In
addition to this, D. p. colombiensis has a relatively narrow disc.
DESCRIPTION.--The dorsal color pattern of D. p. colombiensis con-
sists of a golden tan background with brown spots ranging from 1/4 to 1
times the size of the orbits, arranged fairly symmetrically on the disc,
pectoral fins and tail. The spots range in number from 6 to approximately
50 and are indistinct in some specimens. The disc anterior to the orbits
is usually without markings and is often lacking in all coloration except
for dark, crescent-shaped areas directly in front of the orbits in some
specimens. There are usually from one to three indistinct spots on the
dorsal fins and several spots on the caudal fin. The ventral surface color
is white to cream with no markings.
RANGE.-D. p. colombiensis is known only from the coast of northern
Colombia and ranges in depth from 30 m to 100 m.
REMARKS.--While the dorsal color pattern ofD. p. colombiensis vaguely
recalls that of D. p. pictus, several important distinctions separate the
two. In D. p. pictus the background color of the dorsal surface is tan or







BULLETIN FLORIDA STATE MUSEUM


a. b.


I













c. d. ,





Figure 12. Diplobatis pictus colombiensis: (a, b) Holotype, USNM 226773, female,
149 mm TL, dorsal and ventral views; (c, d) Paratype, USNM 26773, male, 135 mm TL,
dorsal and ventral views; (e) Paratype, USNM 226773, male, 130 mm TL, dorsal view.

light brown with distinctly darker brown spots, but in D. p. colombiensis
the background color is golden tan with only slightly darker brown spots;
in D. p. pictus the spots increase in size toward the edges of the disc
compared with D. p. colombiensis where they do not increase in size;
and D. p. pictus usually has a dark brown blotch beside each dorsal fin
which is lacking in D. p. colombiensis.


Vol. 29, No. 5







FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


ETYMOLOGY. -The subspecific epithet colombiensis is in reference to
the known range for this subspecies.
Diplobatis ommata (JORDAN AND GILBERT 1890)
Discopyge ommata Jordan and Gilbert in Jordan and Bollman 1890:151.
Narcine ommata Clark 1936:383-384.
Diplobatis ommata Bigelow and Schroeder 1948:562-565. MATERIAL
EXAMINED. -24 specimens, listed in Appendix I. Proportional measure-
ments given in Table 2.
DIAGNOSIS.-Diplobatis ommata is distinguished by its dorsal color-
ation, clasper morphology and range. D. ommata also has a relatively
great interorbital distance; a sub-triangular caudal fin usually without a
distinct upper corner; and attains a relatively large size, reaching 250
mm TL.
DESCRIPTION. -External morphology (Fig. 13). Measurements re-
ported here represent the mean value followed by the minimum and
maximum values in parentheses. Disc round- to spade-shaped, 1.02 (0.93-
1.09) times as broad as long; anterior margin of disc evenly rounded to
slightly angular; axis of greatest width 64.2% (60.1-77.0%) of distance
from tip of snout to axils of pectoral fins. Pelvic fins originate anteroven-
trally to or occasionally at axils of pectoral fins; anterior margins of pelvic
fins short, 0.29 (0.23-0.35) times breadth of pelvic fins and 0.5 times or
less the length of the posterior margin of the pelvic fins; angle of anterior
margin of pelvic fins from 450 to 900 to long axis of body; posterior margin
of pelvic fins slightly convex when fully spread; pelvic fins anterior to
rear tips free from or connected to sides of tail for a short distance. Tail
stout, convex dorsally and nearly flattened ventrally, its width midway
between posterior tips of pelvic fins and distal tip of tail 0.51 (0.39-0.64)
times as wide as interorbital distance; tail with a narrow lateral fold along
lateral surface, beginning from opposite midpoint of first dorsal fin to
origin of second dorsal fin and ending at or slightly posterior to origin of
caudal fin; length of tail from center of cloaca to distal tip 0.90 (0.83-
1.00) times distance from tip of snout to center of cloaca. Two dorsal fins
on tail; upper corner of both dorsal fins usually rounded but occasionally
acute; first dorsal fin located entirely over to entirely posterior to pelvic
fins; interspace between first and second dorsal fins 0.61 (0.38-0.83)
times as long as base of first dorsal fin; second dorsal fin usually slightly
taller than first, distance between second dorsal fin and caudal fin 0.73
(0.48-1.02) times as long as base of second dorsal fin. Caudal fin sub-
triangular, usually without a distinct upper corner; base of caudal fin 0.97
(0.88-1.06) times as long, and its height 1.08 (0.86-1.19) times as great
as dorsal lobe of caudal fin.
Preocular length 2.40 (1.90-2.88) times as long as orbit-spiracle dis-


1984
























NI


1"


Figure 13. Diplobatis ommata. (a, b) LACM W60-11, male, 139 mm TL, dorsal and
ventral views; (c, d) LACM 6971-1, female, 193 mm TL, dorsal and ventral views.






FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


tance; preoral length 2.00 (1.63-2.19) times internarial distance; eyes
well developed, diameter of orbit 0.5 times or slightly less interorbital
distance; length of orbit greater than length of spiracle; spiracle ringed
with 7-10 low, rounded papillae. Nasal curtain smooth or slightly crenu-
late, often projecting slightly at midline; nasal curtain often extending
posteriorly to overlap upper jaw and reaching lower jaw when mouth is
fully closed; mouth approximately as wide as nasal curtain. Teeth in both
jaws in a triangular patch, arranged in quincunx, in about 14-16 rows
counting inward at center of jaw, outermost row with one or two teeth
and each succeeding row increasing, making a series of 16-22 teeth in
innermost rows; anterior few rows of teeth usually without cusps, the
succeeding teeth with small, triangular cusps which become increasingly
long and narrow on the posterior teeth, all cusps pointing inward; teeth
completely concealed when mouth is closed, except in a few cases where
two to four rows of teeth may be exposed on lower jaw even when mouth
is closed.
The clasper of D. ommata (Fig. 14) is very short and stout, its diame-
ter the same the entire length; clasper not tapering posteriorly but broadly
rounded; ventrolateral slit (= pseudosiphon?) running along lateral edge
and not extending onto ventral surface; dorsal terminal cartilage folded
1800 to overlie marginals; dermal denticles on rotated surface of dorsal
terminal cartilage; dorsal terminal cartilage forming dorsal wall of clasper
groove, but separated from groove by a fleshy, membranous fold resem-
bling a rhipidon.
D. ommata exhibits a polytypic color pattern with the most common
pattern consisting of a light grayish-brown dorsal background, covered
with small, well-defined dark dots. In the center of the disc there is a
very distinct ocellus with a black or yellow-ochre core, surrounded by a
succession of solid or broken rings of alternating black and pale brown.
Other ocelli consisting of dark brown and ochre spots are scattered on
the disc; some of the spots are darker along the periphery of the ocellus
thereby giving it a ringed appearance and some ocelli are almost solid.
These smaller ocelli are most common at the axils of the pectoral fins, a
pair midway between the central ocellus and the first dorsal fin and one
at the base of each dorsal fin. The preorbital area is usually grayish-brown
with no dark dots, but there may be up to five large dark blotches pre-
sent on the anterior edges of the disc. This area may also have brown
and ochre crescent-shaped areas in front of the orbits, often in the shape
of an M or Y. Other color patterns consist of a very light grayish-brown
background with numerous tiny brown spots and indistinct brown blotches
replacing the smaller ocelli, resulting in a faded, delicate appearance.
Still other specimens may be dark brown with few or no visible markings
except a very darkened central ocellus. The ventral surface is white to







BULLETIN FLORIDA STATE MUSEUM


1 cm









vis vt
IIt
dt
dd
it

Figure 14. External clasper morphology of Diplobatis ommata (LACM W60-11). (a)
ventral view; (b) dorsal view: ap, apopyle; cg, clasper groove; dd, dermal denticles; dt,
dorsal terminal cartilage; It, lateral terminal cartilage; vis, ventrolateral slit; vt, ventral
terminal cartilage.

cream colored, and brown blotches on the anterior dorsal edge of the
disc and pectoral fins frequently continue onto the ventral surface. There
may also be a few dusky areas at the axils of the pectoral and pelvic fins.
RANGE.--D. ommata occurs in the tropical eastern Pacific along the
southwest coast of Baha California, in the Gulf of California and south
along Central America to Panama (Fig. 15). It is very common in inshore
areas (Breder 1928; pers. obs.) and has been reported as deep as 64 m
(Jordan and Bollman 1890).
REMARKS.-As with its congener D. pictus, D. ommata is very vari-
able in its dorsal color pattern, but again there is no correlation between
the various color patterns and sex, location or any other variable. The
suggestion of Breder (1928) that young specimens of D. ommata have
very intricate, distinct patterns that darken and become indistinct with
age does not appear to be correct. We have seen small specimens of this
species that were very dark with few markings, save the central ocellus,
as well as larger specimens with very intricate and distinct patterns. De-
spite the variation in the color pattern of D. ommata, the central ocellus
is present at all times.

INTERRELATIONSHIPS WITHIN THE FAMILY NARCINIDAE

The four genera of Narcinidae (Benthobatis, Diplobatis, Discopyge,
and Narcine) form a monophyletic group clearly separated from other
genera of Torpediniformes and distinguished by the following characters:


Vol. 29, No. 5







FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


United States


Mexico


Pacific
Ocean


o 835'N,79043'W
Chame Pt., Panama


C 8006'N,78051'W
Gulf of Panama


Figure 15. Map of Baha California and northwestern Mexico showing the distribution
of Diplobatis ommata specimens examined in this study. Circled numbers indicate the
number of specimens examined from that locality. Some locations represent multiple lots.


24




220




200































































Figure 16. Schematic illustrations showing the major skeletal elements of the four
genera of Narcinidae. (a) Narcine; (b) Discopyge; (c) Benthobatis; (d) Diplobatis. All illus-
trations represent a ventral view of a mature female.






FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


broad, trough- or shovel-shaped rostrum; ventrolaterally directed nasal
capsules; forked, antler-shaped antorbital cartilages; large precerebral fossa;
tranverse mouth with well developed labial cartilages; anterior hypob-
ranchial elements large and nearly meeting mid-ventrally; and a large
basibranchial copula (Compagno 1973).
Phylogenetic analysis of the relationships between the four narcinid
genera is difficult for two reasons. First, the polarity of many character
states used in batoid systematics is difficult to define due to a very poor
fossil record, many instances of parallel evolution, and a lack of under-
standing of the character states of pleisomorphic taxa (out-groups) (Com-
pagno 1977). Secondly, while each of the four genera exhibit several unique
characteristics (autapomorphies), synapomorphic character states (i.e.
shared, derived characters) are scarce. Only the latter can be used to
determine phylogenetic relationships, i.e. taxa sharing an immediate
common ancestor (Hennig 1966; Wiley 1979).
The four genera are very conservative in their internal anatomy (Fig.
16). However, Discopyge and Narcine share two characters that are con-
sidered to be synapomorphic. The iliac processes on the pelvic girdle of
Narcine and Discopyge are very well developed (when compared to those
of Diplobatis and Benthobatis) and represent the derived condition, as
primitive batoids (Pristiophorus and Rhinobatos) have very poorly de-
veloped iliac processes (Garman 1913). The posterolateral processes on
the antorbital cartilages of these two genera also seem to be derived, as
it is a more complex structure than the antorbital cartilages of other nar-
cinids and of primitive batoids. Based on these two characters and on the
lack of any other synapomorphic character states within the family, Dis-
copyge and Narcine are considered to be sister groups, and they in turn
form the sister group of Benthobatis and Diplobatis (Fig. 17). The tricho-
tomy of Narcine-Discopyge, Benthobatis, and Diplobatis cannot be re-
solved with our present state of knowledge.







X2


Figure 17. Cladogram illustrating possible phylogentic relationships within Narcini-
dae. Numbers refer to the following synapomorphies. (1) relatively well developed iliac
processes on the pelvic girdle; (2) postlateral processes on the antorbital cartilages.








BULLETIN FLORIDA STATE MUSEUM


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Helwig. J.T., and K.A. Council (editors). 1979. SAS Users Guide. 1979 Edition. SAS
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BULLETIN FLORIDA STATE MUSEUM


APPENDIX I


MATERIAL EXAMINED1


Diplobatis pictus pictus

BRAZIL: MCZ 40373 (7:110-162); MCZ 40411 (2:74-102); MCZ 42466 (3:81-*); USNM
156775 (6:131-172); USNM uncat., Oreg. II 17688 (3:124-132); Oreg. II 17626 (2:103-
127); Oreg. II 17694 (1:131).
FRENCH GUIANA: MCZ 40213 (2:88-130); MCZ 42455 (2:138-140); USNM 159882
(1:140); USNM uncat., Oreg. II 10530 (1:81*); Oreg. II 10577 (1:109); Oreg. II 10599
(1:105); Oreg. II 17622, 17623 (3:131-173); Oreg. II 17626 (2:145-158).
SURINAM: MCZ 40397 (2:101-116*); USNM 156771 (1:127); USNM 156784 (1:103);
USNM 159232 (2:97-132); USNM 186422 (2:97-136); USNM 186423 (2:120-134); USNM
226774 (4:75-137); USNM uncat., UNDP/FAO Calamar (5:1572); RMNH 24706 [Holo-
type, D. altenai] (1:140); RMNH uncat., (57:48-130); TCWC 1901.1(1:98); TCWC 1904.1
(1:112); TCWC 1905.1 (1:110); TCWC 1906.1 (1:86).
GUYANA: BMNH 1961.8.31:24-28 (5:105-145); MCZ 40234 (1:130); MCZ 40378 (2:86-
118*); USNM 156786 (1:95) USNM 19711 (2:*); USNM uncat., Oreg. II 10499 (2:89-
112*); Oreg. II 10505 (1:104); Oreg. II 10515 (11:117-128*); Oreg. II 10516 (1:125); UNDP/
FAO Calamar 651 (3:*); UNDP/FAO Calamar 675 (5:*).
VENEZUELA: UF 29893 (8:60-146); UF 29894 (2:104-138); UF 29883 (1:115*); UF
29882 (1:135); MCZ 40377 (4:99-117*); MCZ 40404 (1:125); MCZ 40410 (2:94-107); USNM
uncat., UNDP/FAO Calamar 660 (3:*); TCWC 1900.1 (1:119).


Diplobatis pictus guamachensis

EASTERN VENUZUELA: UF 29884 (1:120); USNM uncat., Oreg. I 4476 (2:150-
151*).
GULF OF VENEZUELA: UF 29869 (1:*); UF 29870 (1:119); UF 29871 (7:99-130);
UF 29872 (3:89-105); UF 29876 (4:104-132*); UF 29879 (3:*); UF 29880 (1:174); UF 19881
(3:141-170); UF 19885 (1:158); UF 29890 (1:148); UF 19891 (1:*); MCZ 48721 (1:196);
MCZ 51052 (2:151-156); USNM 226776 (2:138-149*); USNM 226777 (3:100-147); USNM
uncat., Oreg. I 4392 (4:*); Oreg. I 4467 (2:*).


Diplobatis pictus colombiensis

COLOMBIA: UF 29877 (2:107-126*); UF 29878 (2:73-125*); USNM 226773 (4:107-
166); USNM 232494 [Holotype, D. p. colombiensis] (1:150); USNM 232929 [Paratypes,
D. p. colombiensis] (2:130-135).






'Lots marked with an asterick(*) contained damaged specimens, some of which were not measured.
2Sample contained one female that contained four embryos. Because of their underdeveloped state, measurements were
not taken on the embryos.


Vol. 29, No. 5








FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


Diplobatis ommata

GULF OF CALIFORNIA: LACM W55-85 (1:203); LACM W59-12 (1:187); LACM
W60-11 (1:139); LACM 31759-1 (4:128-192); LACM 6962-23 (10:193-246); LACM 6971-
7 (5:144-226); USNM 46723 (1:159).
PANAMA-COLOMBIA: LACM W53-310 (2:115-126); USNM 41133 [Holotype, D.
ommata] (1:158).




Table 1.
Proportional measurements of Group A (Diplobatis pictus pictus), Group B (D. p.
guamachensis) and Group C (D. p. colombiensis). Proportions in percent ot total length.

Group A (n=98) Group B (n=38) Group C (n=16)

K Range x Range K Range


Total length (mm)
Disc width
Disc length
Snout length:
Preocular
Preoral
Snout to maximum disc width
Snout to axil of pectoral fins
Jaw width
Nasal curtain:
Width
Length
Distance between:
1st gill openings
5th gill openings
Orbits
Orbit and spiracle length
Pelvic fin:
Anterior lobe
Posterior lobe
Breadth of pelvic fins
Tail width at axil of pectoral fins
Height:
1st dorsal fin
2nd dorsal fin
Length:
1st dorsal fin
2nd dorsal fin
Caudal fin:
dorsal lobe length
ventral lobe length
height
Snout to cloaca length
Cloaca to origin of caudal fin


125.2 60.5-173.0 133.1 97.6-195.9
47.6 40.0-55.1 46.1 42.2-50.6
47.0 43.0-55.4 46.4 41.1-51.6


8.4-12.6
10.5-15.2
21.5-37.1
30.9-55.3
4.9-7.8


6.8-12.0
10.0-14.9
19.4-36.3
39.7-48.3
6.3-8.0


130.2 103.2-165.8
43.3 39.4-48.7
44.0 33.6-47.2


10.2-13.6
11.5-15.8
25.2-37.6
41.1-48.3
6.6-8.6


6.5 3.6-8.1 6.4 5.4-7.1 6.7 5.8-7.7
1.8 0.8-3.1 1.9 1.4-2.5 1.6 1.1-2.1


12.2-16.3
7.6-12.2
3.9-7.3
5.1-8.8

8.9-15.7
15.3-31.7
27.9-43.2
6.4-12.3


9.4-15.1
20.5-29.0
31.8-38.6
6.5-10.2


10.1-15.6
17.7-24.0
30.2-37.4
6.1-10.8


6.9 5.0-9.1 7.4 4.6-9.5 6.6 5.1-8.8
7.4 4.6-9.7 7.7 4.6-9.5 6.8 4.7-7.3

5.8 3.9-7.5 6.2 5.0-7.7 5.3 4.3-6.6
6.0 4.2-7.7 6.5 5.1-7.5 5.8 4.7-7.3


9.7-17.7
10.0-15.4
9.3-16.4
43.1-59.0
20.0-48.2


13.8 12.0-16.4
11.7 10.0-15.4
13.3 11.7-15.5
53.0 42.7-69.3
33.6 27.0-38.2








BULLETIN FLORIDA STATE MUSEUM


Table 2.
Proportional measurements and meristics of the Atlantic forms of Diplobatis and
Diplobatis ommata. Proportions in percent of total length.


Total length (mm)
Disc width
Disc length
Snout length (preocular)
Snout length (preoral)
Snout to maximum disc width
Snout to axil of pectoral fins
Jaw width
Nasal curtain width
Nasal curtain length
Distance between
1st gill openings
5th gill openings
orbits
Orbit and spiracle length
Pelvic fin (anterior lobe)
Pelvic fin (posterior lobe)
Breadth of pelvic fins
Tail width at axil of pectoral fins
Height of 1st dorsal fin
Length of 1st dorsal fin
Height of 2nd dorsal fin
Length of 2nd dorsal fin
Caudal fin
dorsal lobe length
ventral lobe length
height
Snout to cloaca length
Cloaca to origin of caudal fin
Number of tooth rows (upper jaw)
Number of vertebrae
Number of pelvic radials


Diplobatis
(Atlantic forms)
n=152

x Range

128.9 60.5-195.9
46.4 39.4-55.1
45.9 33.6-55.4
10.7 6.8-13.6
12.9 10.0-15.8
29.7 19.4-37.6
44.7 30.9-55.3
6.8 4.9-8.6
6.5 3.6-8.1
1.8 0.8-3.1

13.9 11.6-16.3
9.5 7.2-12.2
5.7 3.9-7.3
6.9 4.7-8.8
12.4 8.9-15.7
22.4 15.3-31.7
34.5 27.9-43.2
8.8 6.1-12.3
6.9 5.0-9.7
5.8 3.9-7.7
7.4 4.6-9.7
6.1 4.2-7.7

14.2 9.7-17.7
12.4 7.8-18.2
12.7 9.3-16.4
52.5 42.7-69.3
32.9 20.0-48.2
18 (n=3)
103 98-109 (n= 10)
18 16-21 (n=10)


D. ommata
n=26

x Range


180.2
47.7
46.9
10.6
11.9
29.1
45.4
6.5
5.9
1.6

13.2
9.9
6.5
6.2
11.3
24.2
35.6
8.0
7.2
6.2
7.8
6.7


114.5-245.6
41.9-52.5
42.8-52.3
9.3-14.4
10.2-17.0
25.9-35.7
41.6-50.2
5.7-7.4
5.1-6.7
1.1-2.4

11.9-15.2
8.1-13.0
5.1-7.9
5.7-7.0
8.4-12.6
16.9-31.8
30.1-39.9
6.5-11.4
6.2-8.5
4.2-7.8
6.1-8.3
5.5-7.7


12.5 10.2-15.1
12.0 9.1-14.7
13.1 10.9-14.5
52.6 49.8-54.9
33.0 23.6-36.5
18-19 (n=2)
104 97-112 (n=50)
19 17-20 (n=5)


Vol. 29, No. 5








FECHHELM & MCEACHRAN: DIPLOBATIS REVISION


Table 3.
Proportional measurements of Diplobatis altenai compared with Diplobatis pictus.
Proportions in percent of total length. The measurements of D. altenai are those
of the holotype.

D. pictus (n=152)
x Range D. altenai

Total length (mm) 128.9 60.5-195.9 140.0
Disc width 46.4 39.4-55.1 41.4
Disc length 45.9 36.0-55.4 44.3
Snout length (preocular) 10.7 6.8-13.6 11.4
Snout length (preoral) 12.9 10.0-15.8 13.9
Snout to maximum disc width 29.7 19.4-37.6 28.1
Snout to axil of pectoral fins 44.7 30.9-55.3 43.8
Distance between orbits 5.7 3.9-7.3 6.0
Distance between spiracles 6.9 4.7-7.9 6.1
Mouth width 6.8 4.9-8.6 6.2
Nasal curtain width 6.5 3.6-8.1 6.5
Nasal curtain length 1.8 0.8-3.1 0.9
Distance between
nostrils 6.3 4.9-8.3 5.7
1st gill openings 13.9 11.6-16.3 11.7
5th gill openings 9.5 7.2-12.2 7.9
Pelvic fin (anterior lobe) 12.4 8.9-15.7 12.9
Pelvic fin (posterior lobe) 22.4 15.3-31.7 21.5
Breadth of pelvic fins 34.5 27.9-43.2 29.4
Tail width at axil of pectoral fins 8.8 6.1-12.3 7.3
Height of 1st dorsal fin 6.9 5.0-9.7 6.8
Length of 1st dorsal fin 5.8 3.9-7.7 6.1
Height of 2nd dorsal fin 128.9 4.6-9.7 7.5
Length of 2nd dorsal fin 46.1 4.2-7.7 5.7
Caudal fin
dorsal lobe length 14.2 9.7-16.4 15.7
ventral lobe length 12.4 7.8-18.2 11.4
height 12.7 9.3-16.4 14.1
Distance between dorsal fins 3.3 2.0-5.1 2.5
Snout to cloaca length 52.5 42.7-69.3 47.9











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