A REVISION OF RIGODIUM (MUSCI: RIGODIACEAE)
WENDY B. ZOMLEFER
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
Wendy B. Zomlefer
I express my deepest appreciation and gratitude to Dana
Griffin, III, for his limitless patience and enthusiastic
guidance throughout my graduate program. I also thank
Walter S. Judd, who also generously provided much
encouragement and many helpful criticisms. The other
members of my committee, Bruce J. MacFadden, Jonathan
Reiskind, and James W. Kimbrough have also greatly assisted
in my project and have improved the quality of the
dissertation with their comments. A very special thank-you
goes to Kent D. Perkins for his help in all computerized
aspects of this study, including data-base management, word
processing and processing of loans. I appreciate also the
advice and hospitality of William R. Buck and Richard Harris
(curators at the New York Botanical Garden) during my two
trips to their institution; Bill Buck has been especially
instrumental in my development as a bryologist.
I could not have completed this revision without the
time and patience of many other individuals. Thomas J.
Whitmore, Stephen B. Linda, and Carmine A. Lanciani helped
with aspects of the statistics; W. Mark Whitten, Stephen J.
Walsh, and Douglas D. Turley assisted as computer
consultants. Donna S. Williams spent numerous hours helping
me with the preparation of my specimens for the SEM. Norris
H. Williams, my job supervisor at the Florida Museum of
Natural History, has been especially generous with his
computer facilities, as well as sympathetic to the problems
surrounding my concurrent employment and school activities.
Howard Crum provided excellent instruction during my tenure
as his assistant at the University of Michigan Biological
Station and graciously sent me an unpublished manuscript
related to my dissertation work. Daniel B. Ward and Dan H.
Nicholson advised me on several difficult nomenclatural
problems. Rhoda J. Bryant and Dianna C. Carver helped with
I thank also the curators of the herbaria listed in the
materials and methods section for the extended loans of
their specimens. Travel money for three trips to study
bryophytes (one to Michigan and two to Puerto Rico) was
provided by the Department of Botany at the University of
By their consistent concern about my graduate program
over the past five years, Graig D. Shaak, Gary S. Morgan,
and Laurie Wilkins (all of the Florida Museum of Natural
History), helped to keep my spirits up. In this regard, I
also thank Susan W. Williams and my sister, Kayla S.
Zomlefer, for their cheerful support.
Finally, I thank my parents, Jack and Dorothy Zomlefer,
who have always encouraged and supported my academic
pursuits, even in my formative years when females were
neither expected nor encouraged to excel in the sciences.
TABLE OF CONTENTS
INTRODUCTION............................. ................ 1
TAXONOMIC HISTORY....................................... 3
MATERIALS AND METHODS .................................. 20
MORPHOLOGY .................. ..................... ..... 25
Axes ....... .................... ............ ....... 25
Leaves ............ ........... ... ................. 28
Axillary Hairs.................................... 30
Paraphyllia and Pseudoparaphyllia................. 31
Perichaetia and Perigonia........................... 32
Chromosome Number.................................. 34
PHYLOGENY.. ................... ......................... 57
Characters for Analysis of Representative
Genera of Superfamily Leskeacanae............... 66
Results of Analyses of Genera...................... 69
Characters for Rigodium Species.................... 72
Results of Analyses of Rigodium species............ 74
Taxonomic Philosophy Concerning Species............ 77
PHENETIC STUDIES......................................... 99
Choice of OTUs and Choice of Specimens............. 100
Choice of Characters............................... 103
Results of the Principal Component Analyses......... 105
PHYTOGEOGRAPHY ............. .......................... 117
TAXONOMIC TREATMENT.................................. 122
Key to the Species of Rigodium..................... 125
1. Rigodium toxarion (Schwagr.) Jaeg............... 130
2. Rigodium brachypodium (C. Mull.) Par............ 167
3. Rigodium adpressum Zomlefer.................... 194
4. Rigodium implexum Kunze ex Schwagr.............. 207
5. Rigodium pseudo-thuidium Dus.................... 220
NOMINA AMBIGUA AND NUDA.................................. 234
LITERATURE CITED....................................... 238
A OTUS (COLLECTIONS) USED IN THE PHENETIC
ANALYSES .............................. ............ 248
B DETERMINATION OF MINIMUM NUMBER OF
MEASUREMENTS PER CHARACTER...................... 254
BIOGRAPHICAL SKETCH..................................... 258
Abstract of Dissertation Presented to the Graduate School of
the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
A REVISION OF RIGODIUM (MUSCI: RIGODIACEAE)
Wendy B. Zomlefer
Chairman: Dana Griffin, III
Major Department: Botany
Rigodium Kunze ex Schwagr., a genus of tropical to
austral-temperate pleurocarpous mosses, is comprised of five
species (plus two varieties). Prior to this study, 26
species were recognized, with five additional species
generally accepted as belonging to other genera. Species of
Rigodium, all dioicous, have wiry stems and branches,
strongly dimorphic stem and branch leaves, extremely
incrassate leaf cells that are prorulose to varying degrees
(depending on the species), and hypnoid peristomes. The
habit varies from arborescent with a well-developed stipe
(B. toxarion, R. adpressum, and R. brachypodium) to more
derived forms with either prolific (R. implexum) or reduced
(R. pseudo-thuidium) branching.
The genus has a disjunct distribution in Central and
South America and southeastern Africa. The plants, usually
epiphytic or terrestrial, generally grow in moist, montane
forests. The center of diversity, where all five species
occur, is in the Andean Cordillera along the Chilean-
Argentinian border in central Chile.
Observations of morphology, including those made with
scanning electron microscopy (SEM), compose the basis of
this revision, which includes computer-assisted analyses of
phenetics (Principal Component Analysis, PCA) and cladistics
(Phylogenetic Analysis Using Parsimony, PAUP). One
previously undescribed species (R. adpressum) and two new
combinations at the varietal level (R. toxarion var.
robustum and R. brachypodium var. tamarix) are presented.
Rigodium is maintained within the monotypic Rigodiaceae,
possibly related to the Thuidiaceae.
As treated here, the genus Ricodium Kunze ex Schwagr.
consists of five species (including two varieties) of
austral-temperate to tropical pleurocarpous mosses from
Hispaniola, Central and South America, eastern Africa, and
Madagascar. The center of diversity of Rigodium, where all
five species occur, is in the Andean Cordillera along the
Chilean-Argentinian border in central Chile. The plants
typically grow as epiphytes (or less often terrestrial,
corticolous, or saxicolous) in moist forests at moderately
high altitudes (up to ca 3800 m).
Although 31 species have been included within Rigodium,
no comprehensive work had been published for the genus until
the present revision. The genus itself is well-defined and
recognizable by the dendroid to frondose habit with wiry
stems and branches and often a well-differentiated stipe
(lower secondary stem). The strongly dimorphic stem and
branch leaves are unusual in the marked tendency toward
ecostate stem leaves (at least those of the "stipe" or lower
stem). Stem leaves are typically strongly spreading to
squarrose, wet or dry. Leaf cells are generally rounded-
quadrate (alar region and margins) to oblong (upper and
midlaminar areas) and incrassate throughout. The plants are
dioicous, and the peristome is hypnoid (Zomlefer and Buck,
This treatment represents the first attempt to
completely review all pertinent literature and specimens in
order to (1) ascertain the species and their relationships
within the genus and (2) to determine the position of the
genus (in a monotypic family) within the scheme of bryophyte
phylogeny using cladistics. The results presented here are
based on qualitative and quantitative analysis of
morphology, ecology, and anatomy of over 2,400 herbarium
specimens. This study is especially pertinent since many of
the habitats where Rigodium occurs (mainly subtropical to
temperate rain forests) are threatened by human activities
(as for example, logging in the Valdivian forests in Chile).
The genus Rigodium was established by Schwagrichen in
1845 with original material of the new species, Rigodium
implexum, coming from southern Chile (Schwagrichen, 1845;
Zomlefer, 1990). The name is taken from the Greek word
"rigos" (= rigid) in reference to the extremely stiff and
wiry stems and branches. Although Muller (1845, 1851)
initially suggested maintaining this new genus rather as a
section within Hypnum, the name became well-accepted in the
literature, with even Muller himself eventually describing
six species using Rigodium as the genus name.
In addition to R. implexum, 19 new species were later
described, plus 11 more transferred to Rigodium from Hypnum
(ten species) and Leskea (one species). Of these 31 valid
species names (Wijk et al., 1967, 1969; Crosby, 1979), five
have been now generally accepted as belonging to other
genera: R. dentatum Dix. = Rhvnchostegiella zevheri (C.
Mull.) Broth., R. reflexum (Stark.) Kindb. = Brachythecium
reflexum (Stark.) B. S. G., R. schlosseri (Sendtn.) Kindb. =
Camptochaete schlosseri (Sendtn.) Par., R. vaqum (C. Mull.)
Reichdt. = Camptochaete vaga (C. Mull.) Broth., and R.
varium (Hedw.) Kindb. = Amblystegium varium (Hedw.) Lindb.
In addition, four more Rigodium types examined in the
initial stages of this study have also been reassessed
(Zomlefer & Buck, 1990): R. toxarioides Broth. & Par. (Fig.
1) and R. crassicostatum Bartr. in Christ. (Fig. 2) both =
Eurhynchium praelonaum (Hedw.) B. S. G.; R.
pteriyvnandroides (Broth.) Broth. (Fig. 3) = Helicodontium
pervirens (C. Mull.) Par.; and R. riparium Sehnem (Fig. 4) =
Helicodontium complanatum Broth. This leaves a total of 22
valid epithets (Table 1) incorporated into the present
study--20 associated with Hispaniola and Central and South
America, and one each with eastern Africa and with
The authors of the original species descriptions have
generally emphasized subtle differences in characters, such
as the relative size and fragility of the plants and the
coarseness of the serrations on the leaves. By apparently
comparing type specimens only, the authors did not
sufficiently evaluate the intergradation of these characters
throughout the genus and thus may have overlooked numerous
specimens which bridged the apparent morphological gaps
between the type specimens. The most obvious "species"
based on the old literature are R. pseudothuidium/R.
hvlocomioides (both with distinct habit and a reduced costa
in the stem leaves) and R. implexum (very stiff plants with
unusual right-angle branching). Certain names tended to be
associated only with collections from the particular country
of the type specimen, such as "R. solutum" with Ecuador and
"B. leptodendron" with Bolivia (see Table 1). Adding to the
confusion, authors of floristic treatments tended to lump
indiscriminately several names in synonymy, such as Jaeger
[1878; R. toxarion = R. implexum, B. brachypodium, and
Hypnum (Riqodium) solutum], Muller [1882, Hvpnum (Riqodium)
argentinicum = E. implexum and R. brachypelma
(brachypodium)], and Mitten [1869; Hypnum (Rigodium)
toxarion = H. implexum, H. brachypodium, H. solutum, and R.
lechleri (arborescens)]. Brotherus' (1925) key to 17
species separates out only the few obvious forms (i.e., R.
implexum, R. hvlocomioides, and several species no longer
included in Rigodium) and lumps the remaining 12 species (by
country) under the first general dichotomy of the key (habit
The great need for a full-scale revision of Rigodium
has been noted by authors from Reimers (1926) to Robinson
(1975). In reviewing Chilean collections of bryophytes and
examining numerous specimens of Rigodium in particular,
Reimers (1926) and Herzog (1938, 1954) both concluded that
making any decisions about the taxonomic validity of
Rigodium species was virtually unfeasible without
monographic studies. In fact, Reimers promised a
forthcoming revision (which never appeared). Herzog (1939)
and Bartram (1960) each described a new species of Rigodium
(R. pendulum and R. crassicostatum, respectively), while at
the same time admitting the near impossibility of applying
any specific names without a critical revision of the entire
Other than the keys of Brotherus (1909, 1925), no
attempt has been made to distinguish all the species of the
genus, although several workers have treated a few species
of Rigodium with a regional, floristic perspective. Most
floras do not include descriptions or keys but only list
those species names (and sometimes the specimens) associated
with the area (e.g., Seki, 1976). Notable exceptions are
the floras of Sehnem (1976) and Robinson (1975), which
include keys and some discussion comparing several species.
These two floras, however, are restricted in scope and do
not address Rigodium as a whole. Sehnem's keys for seven
species of Rigodium in his treatment of the mosses of
southern Brazil use vague characters such as a "delicate
habit, similar in aspect to Pterqynandrum or Thuidium." He
described two new species, R. riparium and R. pallidum.
Rigodium riparium Sehnem is actually Helicodontium
complanatum Broth. (Zomlefer & Buck, 1990), and R. pallidum
Sehnem has been reduced to synonymy with R. toxarion
(Schwagr.) Jaeg. in the present study. Robinson's treatment
of the mosses of the well-collected Juan Fernandez Islands
includes detailed discussions of four species (B.
arborescens, R. hvlocomioides, R. toxarion and R. robustum)
with comments on his opinions of synonomy and relationships
to several other species on mainland Chile. By
concentrating on a small, well-collected area, he apparently
made some assumptions about Riqodium species that reflect
better the local variation rather than that found throughout
whole range of the genus. His conclusions are commented on
under the appropriate species in this study.
Coupled with problems in delimitation of the species is
a lack of agreement on the affinities of Rigodium to other
groups. As with many pleurocarpous taxa, Rigodium was
initially allied with Hypnum/Hypnaceae (e.g., Muller, 1851).
By the early twentieth century, more pleurocarpous families
had been delimited, and Rigodium was moved to the
Brachytheciaceae by Brotherus (1909). Later, he (1925)
transferred it to the Lembophyllaceae. Associating the
genus with these two families has persisted until recently.
For example, Robinson (1975) placed Riqodium in the
Brachytheciaceae due to its similarity stipess and strong
heterophylly) with Stokesiella [hom. illeq.; = Eurhynchium
fide Buck (1988)]. More recent publications (Crosby &
Magill, 1981; Vitt, 1982; Walther, 1983) maintain Ricodium
under the Lembophyllaceae, although the validity of this
family, as first conceived by Brotherus, has continued to be
questioned (Crum, 1991). Buck (1980a) reduced the
Lembophyllaceae to two genera (Camptochaete and
Lembophyllum) and suggested placement of Rigodium in the
Thuidiaceae, a move supported by Vitt (1984). According to
Buck, pertinent characters linking Rigodium to the
Thuidiaceae include the pinnate branching, similar leaf
shapes, short leaf cells, and strong single costae.
Bartram (1949) was the first to suggest placement of
Rigodium in a separate family, if not the Brachytheciaceae
or Leskeaceae (in which he included the Thuidiaceae). Crum
(1981, 1984) recently erected the monotypic family
Rigodiaceae, which has been accepted by some authors (Buck &
Vitt, 1986), and tentatively supported by others (Walther,
1983). Although he later (1991) agrees with Buck (1980a)
and acknowledges a close resemblance of Rigodium to the
Thuidiaceae, Crum maintains that the "stipitate growth,
smooth leaf cells, and absence of paraphyllia" merit
separate familial status for the genus.
The present study recognizes five species (including
two varieties) of Rigodium, including one species described
here for the first time: R. adpressum Zomlefer, R.
brachypodium (C. Mull.) Par. var. brachypodium, E.
brachypodium (C. Mull.) Par. var. tamarix (C. Mull.)
Zomlefer, R. implexum Kunze ex Schwagr., R. pseudo-thuidium
Dus., B. toxarion (Schwagr.) Jaeg. var. toxarion, and R.
toxarion (Schwagr.) Jaeg. var. robustum (Broth. in Skottsb.)
Zomlefer. Considering the initial 22 epithets, the
recognition of only five species represents a 77% rate of
over-description. This figure is consistent with moss
revisions in general: according to Touw's (1974) survey, 73
to 79% of published specific and infraspecific names have
been reduced in synonymy in moss revisions from 1901 to
The results of the preliminary cladistic study and
character analysis in this revision indicate that Rigodium
is phylogenetically intermediate between Echinodium
(Echinodiaceae) and Thuidium (Thuidiaceae), and that all
three taxa are basal in Buck and Vitt's (1986) superfamily
Leskeacanae of the Hypnales (see detailed discussion in
section on phylogeny). With Echinodium as an outgroup for
Rigodium, cladistic analyses identify E. toxarion as the
most ancestral species, R. implexum and R. pseudo-thuidium
as the most derived sister-species in the genus, and R.
brachypodium and R. adpressum as phylogenetic intermediates.
FIG. 1. Type of Rigodium toxarioides Broth. & Par. =
Eurhynchium praelonqum (Hedw.) B. S. G. A. Habit. B.
Detail of stem. C. Stem leaf. D. Branch leaf. E-H.
Areolation of leaf. E-F. Basal cells. G. Median cells. H.
Detail of upper costa showing dorsal spine. All from
Apollinaire s.n., 1905 (H-BR). Copyright 1990 by the
American Bryological and Lichenological Society. Reprinted
with permission from The Bryologist 93 (3): 305.
FIG. 2. Type of Rigodium crassicostatum Bartr. in
Christ. = Eurhynchium praelonqum (Hedw.) B. S. G. A. Habit.
B. Detail of stem. C. Stem leaf. D. Branch leaf. E-H.
Areolation of leaf. E-F. Basal cells. G. Median cells. H.
Detail of upper costa showing dorsal spine. All from
Christophersen & Meiland 907 (BM). A and B copyright 1990
by the American Bryological and Lichenological Society.
Reprinted with permission from The Bryologist 93 (3): 305.
FIG. 3. Type of Rigodium pteriqynandroides (Broth.)
Broth. = Helicodontium pervirens (C. Mull.) Par. A. Habit.
B. Stem leaf. C. Branch leaf. D-G. Areolation of leaf.
D. Basal cells. E. Median cells. F. Acumen. G. Detail of
upper costa showing dorsal spine. H. Capsule. All from
Lindman 52 (H-BR). Copyright 1990 by the American
Bryological and Lichenological Society. Reprinted with
permission from The Bryologist 93 (3): 306.
FIG. 4. Type of Riqodium riparium Sehnem =
Helicodontium complanatum Broth. A. Habit. B. Portion of
plant with sporophyte and perigonia. C. Stem leaf. D.
Branch leaves. E-G. Areolation of leaf. E. Basal cells.
F. Median cells. G. Acumen. H. Capsule. All from Sehnem
21515 pacaA). Copyright 1990 by the American Bryological
and Lichenological Society. Reprinted with permission from
The BryoloQist 93 (3): 307.
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MATERIALS AND METHODS
In the course of this study over 2,400 specimens were
examined from the collections of 43 herbaria: ALTA, B, BA,
BM, BR, C, CANM, CHR, DUIS, E, F, FH, FLAS, G, GB, GOET, H,
IA, JE, KRAM, L, LPB, M, MANCH, MEXU, MICH, MO, MPU, NAM,
NY, O, OXF, P, PACA, RB, RO, S, TENN, U, UPS, UWM, VBI, and
W. The acronyms are standardized according to Holmgren et
al. (1990); specimens indicated as from "Herb. Matteri" are
from the personal herbarium of C. Matteri. The label data
from each specimen were entered into a data base on an IBM-
compatible PC. The user interface for the program, similar
in structure to dBase III PLUS (Ashton-Tate, registered
trademark), was compiled by Kent D. Perkins specifically for
this project using CLIPPER (Nantucket Corp., registered
trademark) language. As exsiccatae are common in bryology,
cataloging the numerous specimens with a data base greatly
facilitated the identification of duplicates and fragmentary
specimens that had incomplete or missing data on the labels.
As computer "records," the specimens could also then be
quickly sorted into any appropriate category ("field")--such
as by collector, country, elevation, type designation, or
reproductive state--for use in specimen citations, ranges,
and exsiccatae lists. The modern spellings of geographical
names are according to the United States Office of
Geography's Official Standard Names gazetteer volumes for
Latin America (1955, 1956, 1957, 1963, 1967, and 1968).
Hydrated specimens and permanent slides were examined
for the detailed measurements and qualitative characters
used in the descriptions, phenetic studies, and cladistic
analyses. (The specific methodologies for the cladistic and
phenetic analyses are discussed in their particular
chapters.) Prior to examining them, appropriate portions of
specimens were steeped for several minutes in boiling water.
Occasionally, the entire contents of a packet were soaked if
the plants were inextricably intertwined. The strongly
clasping stem and stipe leaves (only ca 0.45 1.70 mm long)
were individually teased off the stems with fine-tipped
forceps. At least ten to twenty leaves were mounted for
each stipe and stem leaf slide. Leaves, stems, and capsules
were sectioned by hand using single-edged razor blades.
Capsules were cut vertically and the columnae and spores
flushed out. The two capsule sections were then cut into
fourths for the slide.
Permanent slides of whole leaves and sectioned parts
were prepared with Hoyer's solution (Anderson, 1954). The
slides were then heated following application of the cover
slips to clear the air bubbles and flatten the specimens.
Temporary water mounts were prepared of capsules from
specimens with scanty sporophyte material, which was
returned to its packet after examination. At least five
slides were made of each specimen examined, including whole
mounts of the leaves (stipe, stem, branch, perigonial, and
perichaetial) and sections of the stem, stem leaves, and
Measurements of the stems, branches, and capsules, as
well as qualitative observations on habit features (e.g.,
leaf position), were made with the aid of a Wild M5A
Stereomicroscope. Specimens on slides (leaves, cells,
peristome features, and spores) were measured with a Wild
M20 compound microscope equipped with drawing tube.
Measurements were made with an appropriately scaled gauge on
outlines sketched with the drawing tube or directly on the
projected image from the drawing tube. Detailed data
sheets, which included xerox copies of the actual (hydrated)
specimen as a record of the habit, were compiled to organize
The surface details of stem and perichaetial leaves
papillaee, prorosities), peristomes, and spores were
examined and photographed using a Hitachi S-450 scanning
electron microscope (SEM). Specimens were attached to studs
with double-sided tape and then plated with gold in an Eiko
IB-2 ion coater for five minutes at 8 mA prior to SEM
examination. Capsules peristomess) did not require
rehydration and were attached to the stubs in the dry
condition directly from the herbarium specimen.
Spores and leaves, which tended to be collapsed in the
dried state, required special preparation. Stem leaves were
left attached to ca 0.5 1.0 cm stem segments, perichaetia
were removed as a whole unit, and spores were left in their
capsules during rehydration. Due to their small size,
perichaetia and capsules with spores were sandwiched between
1 cm Nucleopore polycarbonate filter papers placed in
modified Beem capsules. All leaves and spores were first
hydrated for 15 minutes in warm water. The leaves of
Rigodium toxarion and R. brachypodium were next placed
through a series of successive ten-minute washes in 25, 50,
75, and 95% ethanol, respectively, followed by two
successive ten-minute rinses in 100% ethanol. The specimens
were subsequently subjected to a critical point drying
sequence composed of five fifteen-minute wash cycles of
liquid CO2 in a Balzers CPD-101 Critical Point Dryer. These
leaves were then coated with gold as described above.
The perichaetia and stem leaves of R. adpressum and all
spores required fixation prior to ethanol rinses and
critical point drying. Otherwise, entire spores and the low
papillae at the base of the perichaetial leaves tended to
collapse, and the decurrent portion of the stem leaves of R.
adpressum curled over. After rehydration in water, these
specimens were soaked in 5% gluteraldehyde in .2M
NaCacodylate buffer for two hours. They were then rinsed
three times in .05M buffer for five minutes and placed in a
1% solution of osmium tetroxide (Os04) in buffer overnight.
After four rinses with distilled water, these specimens were
taken through the alcohol washes, critical point drying
sequence, and coating preparation as described above for the
capsules and other leaves.
Salient morphological features of the genus Rigodium
are included in this chapter, along with a discussion on the
terminology (particularly that of the axes and corresponding
leaves) incorporated in this monograph.
Traditionally, bryologists have used the terms
"primary" and "secondary" to distinguish the stoloniferous
vs. the erect/pendent axes, respectively, of a pleurocarpous
habit (e.g., Arzeni, 1954). Argent (1973) describes in
detail the difficulty in applying these designations to the
different types of shoots in the Pterobryaceae, a
pleurocarpous group. His simplified terminology (stolon,
stems, branches, and flagella) has been adopted by others
(e.g., Allen & Crosby, 1986). Some of Argent's ideas have
been incorporated into this monograph, with the addition of
a few terms peculiar to the habit of Rigodium (stipe vs.
stem, primary, secondary, and tertiary branches), and are
1. "Stolons" (or rhizomes) are often referred to as
"primary stems" by other authors (e.g., Crum, 1981, 1984).
These axes are usually creeping, deeply colored (brown-red
to dark brown) and bear rhizoids. Leaves, when present, are
often achlorophyllous and less well-developed than those on
2. "Stems" and stipess" are general terms for the two
parts of the main axis (or secondary stem of some authors)
of plants which are erect (or pendulous) and are derived
from the stolons. The stipe is the lower, unbranched
portion of the main shoot which is often darkly pigmented.
In Rigodium, stipe leaves are ecostate but are otherwise
well-developed. The term "stem" refers here to the upper,
branched portion of Rigodium plants where the leaves are
3. Branches are ranked in this study as primary,
secondary, and tertiary. Primary branches arise from stems
and are characterized by leaves intermediate in shape and
size of those of the stem/stipe and secondary/tertiary
branches. Secondary branches, which arise from the primary
branches, have narrowly ovate leaves without a well-
developed acumen. Tertiary branches are borne on secondary
branches. The leaves are similar in shape but smaller than
those of the secondary branches.
The delimitation of these types of axes outlined above
is not always clear-cut in Rigodium since they may
intergrade with one another. Allen and Crosby (1986)
suggest that this intergradation in Squamidium is due to
probably very weak genetic control coupled with
environmental influences, which may also be the case in
Rigodium. For example, in addition to the secondary
branches, the upper main axis (stem) may give rise directly
to new main axes (stems), resulting in "stem-like primary
branches" (Figs. 7H-J, 8H-J) that are similar to the
innovations in genera such as Hylocomium (Crum & Anderson,
1981). In Rigodium, though, these "innovations" are not
necessarily restricted to the area just below the
inflorescences, but may arise anywhere along the stem.
Although the term is not used here, Rigodium species also
have "flagellae" as defined by Allen and Crosby (1986): axes
stolonss) which develop from the tips of branches. However,
in Rigodium both branches and stems may root at the tips and
produce new plants (produce either stolons or stems; Fig.
5). Rhizoids, then, may be found at the tips of rooting
stems and branches as well as on the substrate sides of
stolons and stems.
The branching in Rigodium is monopodial (as defined by
Crum & Anderson, 1981) with irregularly pinnate branching.
Three of the species (R. brachypodium, R. adpressum and R.
toxarion) are dendroid with distinct creeping vs. pendulous
(or erect) portions. In R. pseudo-thuidium and R. implexum
the stipe is less distinct and short. R. implexum is
profusely branched, forming well-developed cushions (Fig.
43A). Plants of R. pseudo-thuidium have very little
secondary branching (Fig. 46A).
The various types of axes are similar in anatomy
although branches are much smaller in diameter and with a
less-developed central strand. In all species, several
layers (three to six rows) of small and incrassate epidermal
cells (Fig. 6A and B) form a well-developed rind which
probably contributes to the characteristic stiffness of the
plants. The epidermis has a furrowed appearance in surface
view (Fig. 11C). The cortex (Fig. 6B) consists of large,
hyaline thin-walled cells which usually become smaller
toward the center of the axis. Sometimes the smaller cells
of the cortex form a loosely organized ring around the
central strand as in Fig. 6B. Small, reddish, incrassate
cells comprise the central strand which varies in degree of
development (Fig. 6C and D) but generally consists of ten to
twenty (or sometimes more) cells.
Riaodium is unusual in having ecostate lower stem
(stipe) leaves and costate upper stem leaves, in addition to
the dimorphic stem and branch leaves. Due to intergradation
of axes and corresponding leaf forms, care must be taken in
assigning and comparing "leaf types." Figures 7 and 8 show
the relative changes in size and morphology of leaves along
particular axes in R. toxarion (long acumen) and R.
brachypodium (short acumen). In this study (phenetic
analysis and all descriptions), "stipe leaves" are defined
as those ecostate leaves from the mid-stipe, "stem leaves,"
as those from the mid- to upper stem, and "branch leaves,"
as those from the secondary branches (Fig. 23A).
In all species, stipe and stem leaves are broadly ovate
and taper abruptly to a long or short acumen. The strongly
clasping and concave leaf bases tend to be decurrent (in R.
adpressum, strongly so). All species show a tendency to
form auriculae (Fig. 9A-E), although this character is most
consistent in R. pseudo-thuidium. Stipe and stem leaves are
typically wide-spreading to squarrose, wet or dry, but the
leaves of R. adpressum are appressed with spreading tips.
Branch leaves are consistently ovate (R. pseudo-thuidium) to
usually narrowly ovate (all other species) and are typically
erect to spreading.
Leaf cells are incrassate throughout and the alars are
not differentiated. Cell walls vary from even (R. toxarion)
to uneven (E. brachypodium). Due to the thick walls, the
cells are consistently prorulose, most weakly so in R.
toxarion (Fig. 10A). In the most extreme case (R.
brachypodium), the midlaminar cells project as well-
developed papillae (prorulae) on the dorsal surface (Fig.
10C and D). Although leaf cells in Rigodium are reported as
smooth (Crum, 1981, 1984, 1991), central papillae occur on
the dorsal side of some cells in the decurrent portion of
the stem and stipe leaves of R. adpressum (Figs. 11D, 40F
and G) and at the base of perichaetial leaves of some
specimens of all species (discussed below under perigonia
An outstanding feature of the areolation of Rigodium
stem, stipe, and branch leaves is an apparent intramarginal
border very visible at low power (Fig. 12A and B) and also
distinguishable in cross sectional view of the leaves (Fig.
12C), as well as in surface view with the SEM (Fig. 10B).
The border is formed by four to nine rows of cells that have
much thicker walls than those of the midlaminar cells. The
cells comprising this border are often a different shape
than those of the midlaminar portion of the leaf, as well.
For example, the seven- to ten-cell border in R. pseudo-
thuidium typically is composed of longer and wider cells
than the rest of the leaf, while the narrower border (four
to six cells) of R. adpressum consists of much shorter
cells. The intramarginal border is always present to some
degree but its appearance varies from weak (R. toxarion) to
very strong (R. adpressum), depending on the relative
thickness of the cell walls in comparison to the midlaminar
The costa is absent from the stipe leaves and is
usually present in the stem leaves. The stem leaves of all
species, however, show a tendency for a reduced costa (e.g.,
Fig. 9F-I), which is most consistent and characteristic of
R. pseudo-thuidium. The costa is strongest in R. implexum
(five-stratose in the thickest part) and to a lesser extent,
R. brachypodium (47-96 um wide at base). Branch leaves are
always costate in Riaodium, although the costa may be weak
in R. pseudo-thuidium (Fig. 9H and I).
Recently (Griffin & Buck, 1989), axillary hairs have
been emphasized as useful characters for characterizing
taxonomic groups, especially genera (Saito, 1975) or
groupings of genera, such as subfamilies (Griffin, 1990).
Although not useful for distinguishing between species of
Rigodium, the structure of the axillary hairs is consistent
within the genus: two pigmented basal cells and an elongate,
hyaline terminal cell (Fig. 6E-I). The lower basal cell is
sometimes very lightly pigmented and difficult to see. The
axillary hairs are profuse at the tips of stems and branches
and are easiest to locate in E. adpressum appressedd leaves
which prevent loss of the delicate hairs) and R. pseudo-
thuidium (relatively large leaves with broad bases).
Paraphvllia and Pseudoparaphyllia
Paraphyllia and pseudoparaphyllia are small,
chlorophyllous, filamentous or foliose structures arising on
the stems of pleurocarpous mosses (Rohrer, 1985).
Historically, distinctions between the two structures have
been blurred until recently with the investigations of
Iwatsuki (1963) and Ireland (1971). Paraphyllia, usually
abundant when present, occur everywhere on stems and
branches (Ireland, 1971). Rigodium lacks these structures.
Pseudoparaphyllia, not particularly abundant when found
on moss plants, are restricted to areas around the branch
primordia and mature branches. The structures, distinct for
many species, have recently been emphasized in moss taxonomy
(Buck, 1984). However, foliose pseudoparaphyllia and
rudimentary branch leaves are sometimes confused (Allen,
1987). Generally, pseudoparaphyllia arise strictly on the
stem, while immature branch leaves occur at the base of
branches (Buck, 1984). Ovate, foliose, ecostate structures
occur at the base of branches of Rigodium (e.g., Figs. 7K,
8K). These intergrade with the branch leaves above (Figs.
7L-O, 8L-O) and are interpreted here as rudimentary branch
leaves and not as pseudoparaphyllia. Pseudoparaphyllia do
not occur in Rigodium.
Perichaetia and Perigonia
Rigodium is dioicous, and male and female plants are
indistinguishable. Reports of monoicism in the literature
(e.g., Sehnem, 1976) were due to the inclusion of discordant
elements within the genus, such as species of Helicodontium
(Zomlefer & Buck, 1990). Specimens with archegonial plants
are much more common than those with antheridia. The
infrequency of male populations compared to female in
dioicous mosses has been noted often (Longton & Greene,
1979; Stark, 1987) but not explained.
Both perichaetia and perigonia are bud-like structures
arising laterally along the axes of the plant. Perichaetia
are most common along the stems (but also occur on the
primary branches), whereas perigonia are most frequent along
primary branches, occurring much less often on the stems
(and secondary branches as well). Perigonial leaves (e.g.,
Fig. 28F) are similar to branch leaves in shape and
areolation but are ecostate and also tend to be more broadly
ovate. The inner perigonial leaves may also taper to a
somewhat longer acumen. Perichaetial leaves, weakly costate
to ecostate, are consistently subulate with spreading to
squarrose acumens in all species. The areolation, oblong to
rhombic cells at the base and shorter flexuous cells above,
thus differs from that of the stem leaves (shorter cells
below, cells above not flexuous). In addition, dorsal
central papillae may be found within the some cells near the
base of the outer perichaetial leaves (Figs. 11A and B, 41B
and C). These papillae are consistent on all available
collections of R. adpressum with archegonial plants and are
occasionally to frequently present in the other four species
as well (e.g., Fig. 35B).
Representative examples of gametangia and paraphyses of
Rigodium are illustrated in Figs. 13A-D. Of note is that
the structure of the paraphyses is somewhat similar to that
of the axillary hairs: usually two (but sometimes more)
pigmented cells at the base plus elongate hyaline terminal
cells (several as opposed to one in the axillary hairs).
The paraphyses subtending the antheridia (Fig. 13C) tend to
be stouter than those found within perichaetia (Fig. 13A).
Mature sporophytes are not commonly found on Rigodium
specimens. The morphology of the capsule is consistent
among the species, although the urns of R. pseudo-thuidium
(Fig. 47H) are somewhat larger than those of the other
species. The asymmetric, horizontal to inclined capsule of
Rigodium has a well-developed rostrum (Fig. 13F) on the
operculum. The annulus, consisting of two rows of
incrassate cells, is illustrated in Fig. 13H. The
phaneroporous stomates (Fig. 13G) occur at the base of the
Rigodium has a typical hypnaceous peristome, which does
not vary in structure between species (Figs. 131, 14). The
exostome teeth, cross striolate below (Fig. 14C and D) and
papillose above (Fig. 14B), have well-developed lamellae on
the ventral side (Fig. 14E and F). The endostome consists
of a high basal membrane, well-developed segments (Fig. 14A)
and usually two to three cilia.
The typical spherical and papillose spores are
illustrated in Figs. 13J and 15A-D.
A chromosome number of n = 11 has recently been
reported by Deguchi and Oginuma (1990) for "Rigodium
implexum" (Dequchi 31548, KOCH; specimen not seen).
FIG. 5. General Morphological Features of Rigodium:
Rooting at Tips. From T. Muller 2635 (L).
FIG. 6. General Morphological Features of Rigodium:
Stem Anatomy and Axillary Hairs. A-D. Stem cross sections.
A. Whole stem section indicating position of wedge featured
in B. B. Detail of section showing rind, cortex and well-
developed central strand. C-D. Variation in the development
of the central strand. C. Weak central strand. D. Typical
development of the central strand. A-B from Sehnem 4686
(PACA, E. toxarion); C from Crosby 12984 (MO, R. toxarion);
D from Skottsberq & Skottsberg 418 (S, R. toxarion). E-I.
Representative axillary hairs from each species. E. R.
adpressum (Roivainen 1597, H). F. R. toxarion (Wasum et al.
3964, FLAS). G. R. brachvpodium (Matteri 2274, BA). H. R.
implexum (Crosby 12504, MO). I. R. pseudo-thuidium
(Schiavone 2451, BA).
FIG 7. General Morphological Features of Rigodium:
Changes in Leaf Morphology (Leaf with Long Acumen) along
Various Axes. A. Habit. B. Leaf from stolon. C-E. Stipe
leaves. C. Leaf from stipe base. D. Leaf from mid-stipe.
E. Leaf from stipe apex. F-G. Stem leaves. F. Leaf from
mid-stem. G. Leaf from stem apex. H-J. Leaves from "stem-
like" branch (innovation). H. Leaves from innovation base.
I. Leaf from mid-innovation. J. Leaf from innovation apex.
K-M. Primary branch leaves. K. Leaves from branch base.
L. Leaf from mid-branch. M. Leaf from branch apex. N.
Leaves from secondary branch base (left) to apex (right).
O. Leaves from tertiary branch base (left) to apex (right).
All from Tonduz rPittier No:1 5667 (BR, E. toxarion).
FIG. 8. General Morphological Features of Rigodium:
Changes in Leaf Morphology (Leaf with Short Acumen) along
Various Axes. A. Habit. B. Leaf from stolon. C-E. Stipe
leaves. C. Leaf from stipe base. D. Leaf from mid-stipe.
E. Leaf from stipe apex. F-G. Stem leaves. F. Leaf from
mid-stem. G. Leaf from stem apex. H-J. Leaves from "stem-
like" branch (innovation). H. Leaves from innovation base.
I. Leaf from mid-innovation. J. Leaf from innovation apex.
K-M. Primary branch leaves. K. Leaves from branch base.
L. Leaf from mid-branch. M. Leaf from branch apex. N.
Leaves from secondary branch base (left) to apex (right).
O. Leaves from tertiary branch base (left) to apex (right).
All from Elliott 139 (H, R. brachypodium).
FIG. 9. General Morphological Features of Rigodium:
Aspects in Leaf Morphology. A-E. Examples of auriculate
leaves in the various species (rare in all but R. pseudo-
thuidium). A. R. pseudo-thuidium (Halle & Skottsberq 842,
S). B. R. brachvyodium (Dusen 357, W). C. R. adpressum
(Kuhnemann 5260, ALTA). D. R. implexum (Poeppia s.n., BM).
E. R. toxarion (Landrum 240, MO). F-I. Stem leaves from a
collection of R. toxarion, showing unusual variation in
costa development (Tonduz rPittier No:1 5667, BR).
FIG. 10. General Morphological Features of Rigodium:
Scanning Electron Micrographs of Leaf Surfaces. A. Dorsal
side of R. toxarion stem leaf showing weakly prorulose
midlaminar cells. B. Ventral side of R. brachypodium stem
leaf (arrow indicates intramarginal band of cells). C.
Dorsal side of R. brachypodium stem leaf showing projecting
end walls (prorulae) of midlaminar cells. D. Detail of C.
A from Tonduz [Pittier No:l 5667 (BR); B-D from Crosby 12992
(MO). A: line = 25 um; B, C: = 50 um; D: = 10 um.
FIG. 11. General Morphological Features of Rigodium:
Scanning Electron Micrographs of Leaf Surfaces in R.
adpressum. A. Whole perichaetium (arrow indicates position
of detail in B). B. Detail of dorsal surface of
perichaetial leaf base showing papillae. C. Stem leaves
(arrow indicates decurrent portion). D. Detail of
decurrency showing papillae. A-B from Dusen 397 (S), C from
Matter & Schiavone 4985 (Herb. Matteri, D from Cantino M-
11 (MO). A: line = 250 um; B: = 15 um; C: = 100 um; D: = 25
FIG 12. General Morphological Features of Rigodium:
Areolation of Stem Leaf. A. Stem leaf showing location of
view in B. B. Portion of stem leaf with various zones
labelled. C. Cross section of stem leaf with zones
corresponding to B. All from Claude-Joseph 5775 (FH, R.
-*-costa -midlaminar cells -cells marginal cells
5030 frn ,q
80 0 \
0 00 SS225S22235^
0^ 50AIm- 41
FIG. 13. General Morphological Features of Rigodium:
Sporophytic and Associated Gametophytic Structures. A.
Paraphysis from perichaetium. B. Archegonium. C.
Paraphysis from perigonium. D. Antheridium. E. Calyptra
from developing sporophyte. F. Capsule. G. Stomate at base
of capsule urn. H. Annulus (still attached to urn and
operculum). I. Portion of peristome. J. Spore. A-B from
Kuhnemann 5260 (ALTA, R. adpressum); C-D from Ruthsatz s.n.
(H, R. adpressum); E from Matteri 432 (BA, R. adpressum); F
from Lechler 629 (MICH, R. brachypodium); G from Stevermark
32769 (F, R. toxarion); H from Ventura 18869a (MEXU, R.
toxarion), I from Hammen et al. 2676 (FLAS, B. toxarion); J
from Matteri & Schiavone 4985 (Herb. Matteri, R. adpressum).
" ', /
FIG. 14. General Morphological Features of Rigodium:
Scanning Electron Micrographs of the Peristome. A. Overview
of peristome. B. Apex of exostome tooth showing papillose
outer surface. C. Base of peristome tooth showing cross-
striolations on the outer surface. D. Detail of C. E.
Inner surface of peristome tooth showing lamellae. F.
Detail of E. A from Kunkel 2029 (H, R. brachypodium); B-D
from Barrandequv 345 (MO, R. pseudo-thuidium); E-F from
Neaer 10 (L, R. brachypodium). A: line = 100 um; B, C: = 25
um; D, F: = 10 um; E: = 50 um.
FIG. 15. General Morphological Features of Rigodium:
Scanning Electron Micrographs of Spores. A-D.
Representative spores. A-B from Hollermayer 281 Ep.. (S, R.
brachypodium); C-D from P6cs 6782/B (VBI, R. toxarion). All
lines = 5 um.
Cladistic methodology has been developing in zoology
and botany over the past three decades, but has been
infrequently applied to systematic studies in the
bryophytes. The disadvantages of using bryophytes as the
subjects for cladistic study are discussed in detail by
several bryologists, such as Robinson (1985, 1986) and Buck
(1986). However, these problems with cladistics (e.g.,
difficulty of determining homology, choosing outgroups, and
dealing with character loss) exist in "traditional"
taxonomic work as well (Mishler, 1986). The primary
benefits of cladistic analysis are: (1) the care in which
characters is presented: the characters, their polarity, and
their level of universality must be stated explicitly in
order to support a cladogram, and (2) the ability to
construct an explicit hypothesis of genealogical
Few studies have incorporated pleurocarpous groups
(including Rigodium) in a phylogenetic framework.
Historically, most bryologists have concentrated on
describing new species and genera; few have dealt with
delimitation of groups based on phylogeny (Buck & Crum,
1990). Family definitions, established at the turn of the
century and generally based on European taxa, became more
and more heterogeneous as newly described genera were added.
Recently, the circumscriptions of moss families and genera,
particularly those of the pleurocarps, are being radically
revised, but no scheme using strict Hennigian principles for
the pleurocarps has yet been published.
Trees showing relationships among pleurocarpous
families have been presented by Vitt (1984) and Buck and
Vitt (1986). Vitt (1984) applies character analysis at the
subordinal level (= orders in other classifications, i.e.,
Bryineae, Hypnineae, Leucodontineae, Hookeriineae) for the
Bryales, but his dendrogram of the families groups them
"according to similarity." In this scheme, Rigodium is
included within Thuidiaceae, shown as a sister group to the
Echinodiaceae. The survey of pleurocarpous families
presented by Buck and Vitt (1986) results in some
revolutionary alignments of families, some of which are
shifted between orders. The authors admittedly use both
symplesiomorphies and synapomorphies in the construction of
their "pseudocladogram." Explanations of the polarities of
characters, as well as their level of universality, are not
often offered but are convincing when given (e.g., for
peristomal development characters and leaf cell shape).
Figure 16 is a redrawn version of their cladogram of the
Hypnales with the cited plesiomorphic characters deleted,
resulting in unresolved branching points in the
superfamilies Hypnacanae and Brachytheciacanae. For
simplicity, autapomorphies are not included here as the
assumption is being made that the families are monophyletic.
The numbers of the character sets, listed in Table 2, follow
the original list of Buck and Vitt (1986). Numbers for the
plesiomorphic and autapomorphic characters are deleted here.
According to Buck and Vitt, the members of the Hypnales
lineage, all pleurocarpous, are characterized additionally
by hypnoid peristomes, elongate leaf cells, horizontal and
asymmetric capsules, and distinctive exostomal ornamentation
(outer surface cross-striolate below and coarsely papillose
above; inner surface with projecting trabeculae). The
Hypnales are further divided into three suborders: the
Hypnodendrineae, Fontinalineae, and Hypnineae. The
Rigodiaceae are classified within the Hypnineae, the most
advanced hypnalean suborder, characterized by well-developed
peristomal development (character 11, shouldered teeth).
The division of this suborder into three superfamilies is
based on gametophytic characters: the families of the basal
superfamily Leskeacanae (in which the Rigodiaceae are
included) are linked by the strong synapomorphy of
secondarily shortened leaf cells, plus a weaker character
cited as a tendency for papillosity (of various types) of
leaf cells. (That the latter character is found in other
groups is not directly addressed by the authors, and
additionally, the various kinds of papillae found in these
and other families are not distinguished.) The authors
postulate that these characters may be adaptations for water
retention in exposed habitats.
The five families composing the Leskeacanae
(Pterigynandraceae, Leskeaceae, Thuidiaceae, Echinodiaceae
and Rigodiaceae) have undergone numerous and ongoing
revisions. The family Pterigynandraceae was erected by Buck
(1980a) as a monotypic family, which has been recently
expanded to include four more genera (Buck & Crum, 1990).
The family is characterized by reduced costae, prorulose
leaf cells, and reduced peristome (smooth exostome;
endostome reduced to slender segments).
The Leskeaceae have historically been considered part
of, or close to, the Thuidiaceae (e.g., Grout, 1932) and due
to the reduced peristome of some genera, have even been
included within the Isobryales (Leucodontales; Buck, 1980a;
Vitt 1982, 1984). Buck and Vitt (1986) recognize a more
restricted Leskeaceae, as first suggested by Crum (1973),
with Anomodon and allies excluded. According to their
definition, the family is reduced to Leskea and Pseudoleskea
plus their associated relatives and are characterized by
strong tendencies of cells to be papillose over the lumina,
limited presence of paraphyllia, and orange exostome with
reduced striations (usually papillose). Recently, Buck and
Crum (1990) transferred several genera (e.g.,
Brvohaplocladium and Claopodium, discussed below) to the
Leskeaceae from the Thuidiaceae, primarily recognizing the
family on the basis of gametophytic characters and
perceiving "a habitat-driven, sporophytic reduction series
with Leskea as the reductionary extreme."
The Thuidiaceae s.l., sometimes combined with the
Leskeaceae, historically included several subfamilies (see
Watanabe, 1972). Buck and Vitt (1986) excluded Anomodon
from the family and simply defined it on the basis of
papillose leaf cells and abundant paraphyllia. Buck and
Crum (1990) further reduced the family to only the subfamily
Thuidioideae, with members of the other subfamilies
transferred to other families (discussed below).
The Echinodiaceae, a small monotypic family, have
sometimes been included in the Isobryales (e.g., Walther,
1983), but according to Buck and Vitt (1986) and Churchill
(1986), the plants have a standard hypnalean peristome. The
coarse, poorly branched plants have an unusual (and possibly
relict) Macaronesian-Australian-New Zealand distribution.
The monophyly of the superfamily Leskeacanae is based
on Buck's and Vitt's suite of characters represented by "12"
in Fig. 16; of these, the secondarily derived short leaf
cells is their strongest and best defined synapomorphy. For
the purposes of this study, the assumption is being made
that the superfamily is a natural and monophyletic group,
until such a time when a higher level phylogenetic analysis
(based on shared derived characters) is completed on all the
families of the Hypnales (as well as for the Leucodontales
and Hookeriales). These families continue to undergo much
redefinition, including transfer of genera between them
(even since the cladogram of Buck and Vitt was published).
The following representative genera of the superfamily have
been chosen for a preliminary cladistic analysis in an
attempt to better ascertain the phylogenetic position of
Riqodium. The affinities of several of the genera
themselves, as outlined below, have also not been agreed
upon as they are shifted around between families of the
Pteriqynandrum, a monotypic genus (Buck, 1980b), was
included in the Entodontaceae (Crosby & Magill, 1981; Vitt,
1982) and tentatively in the Leskeaceae in the Isobryales
(Vitt, 1984). The genus initially comprised the
Pterigynandraceae (Buck, 1980a) until Buck and Crum (1990)
expanded the family. Buck (1980b) stated that the genus was
clearly an isolated group with no obvious connections to
other genera, but Buck and Crum (1990) acknowledge a
relationship with Leskeaceae and Thuidiaceae.
Leskea and Pseudoleskea represent the major groups of
Leskeaceae s.s., with Pseudoleskea characterized by a normal
hypnalean peristome, and Leskea, having the reductionary
extreme of the sporophyte.
Thuidium, Brvohaplocladium, Claopodium, Heterocladium,
and Helodium represent the diverse Thuidiaceae s.1.
Thuidium, Bryohaplocladium [= Haplocladium nom. ille fide
Watanabe & Iwatsuki (1981)], and Claopodium have been
included in the subfamily Thuidioideae s.l. The close
relationship between Claopodium and Brvohaplocladium has
long been recognized (Noguchi, 1964; Watanabe, 1972), and
the genera have been sometimes included within the
Anomodontaceae, as well as the Thuidiaceae. Buck and Crum
(1990) recently transferred them to the Leskeaceae as part
of the reduction series within the family. Of note here is
that Noguchi (1964) in his monograph of Claopodium suggested
that it may possibly not be monophyletic. Heterocladium,
previously within the subfamily Heterocladioideae of the
Thuidiaceae s.l., has been added to the expanded
Pterigynandraceae (Buck & Crum, 1990) as part of a reduction
series within that family. Helodium, a small genus of three
species (Abramova & Abramov, 1972), was formerly included
within the subfamily Helodioideae. Buck and Crum (1990),
somewhat unsure of its placement, erected the new monotypic
family, Helodiaceae, to accommodate it.
Echinodium is the small genus of six species comprising
the Echinodiaceae. According to Churchill (1986), the
monophyly of the genus is questionable since it is not well-
defined on the basis of shared derived characters.
The problems in placement and previous inclusion of
Rigodium within various families (Brachytheciaceae,
Lembophyllaceae, Thuidiaceae) are discussed in detail in the
section on "Taxonomic History." Crum (1981, 1984) recently
circumscribed the monotypic Rigodiaceae.
Phylogenetic reconstruction and character polarization
depend on the proper selection of an outgroup. Often a
functional or provisional outgroup is the best available
choice (see Watrous & Wheeler, 1981). According to Buck and
Vitt (1986; Fig. 16), the suborders Fontinalineae
(Fontinalaceae) and Hypnodendrineae (Pterobryellaceae,
Thamnobryaceae, Pleuroziopsidaceae, and Hypnodendraceae) are
the outgroups for the suborder Hypnineae (including
superfamily Leskeacanae). The choice of using these groups
is problematical for the following reasons. Most of these
families had been scattered among several orders and are
tentatively allied by Buck and Vitt in the Hypnales for the
first time. The use of characters of the Fontinalaceae
(traditionally in the Isobryales) is difficult due to the
extreme modifications in both the sporophyte and gametophyte
for an aquatic habitat. The synapomorphies (character set
2: exostome teeth long, gametophores dendroid, endostome
segments gaping, leaves coarsely serrate) for the
Hypnodendrineae may be weak, as arguments concerning the use
and polarities of these particular characters are not
presented. Two of these families, the Pterobryellaceae and
Thamnobryaceae, were previously subfamilies of the
Neckeraceae (subfamily Pterobyelloideae and Thamnoideae,
respectively) in the order Isobryales (Vitt, 1982, 1984).
(Buck and Vitt maintain the rest of the Neckeraceae in the
Isobryales.) The monotypic Pleuroziopsis comprises the
Pleuroziopsidaceae (Ireland, 1968), previously allied with
the Climaciaceae (Isobryales), but now segregated into its
own family due to several unusual characters. The
Hypnodendraceae have traditionally been considered as an
acrocarpous family in the Bryales (Vitt, 1982, 1984), but
Buck and Vitt (1986) follow Touw (1971) in interpreting the
habit as having compressed pinnate branching.
For the preliminary investigation of the representative
genera of superfamily Leskeacanae, Pleuroziopsis
(Pleuroziopsidaceae) and Thamnobryum (Thamnobryaceae) were
chosen as provisional outgroups for rooting the trees
presented here (Figs. 17, 18). As discussed below, the
results of these analyses suggest Echinodium as the possible
outgroup for the cladistic analysis of RiQodium species,
enabling the polarization of characters within Riqodium in
an effort to determine the possible phylogenetic
relationships of the species. These cladistic analyses were
generated using the software program Phylogenetic Analysis
Using Parsimony (PAUP), Version 3.0 (Swofford, 1990) on a
Macintosh computer. PAUP and similar software are
summarized and compared by Platnick (1987). The cladograms
were rooted using the particular outgroups as indicated in
the discussions below under the appropriate analyses. The
searches for the shortest trees included the heuristic
option "MULPARS" (multiple parsimony) along with branch-
swapping, as well as branch-and-bound. Equivalent results
were obtained with both methods. When more than one minimal
tree resulted from an analysis, a strict consensus tree also
was calculated. Characters for multistate taxa, as coded in
Tables 3 and 5, were included and interpreted as
"polymorphism" (as opposed to "uncertainty").
Autapomorphies were excluded from the computer analyses (so
as to not influence the consistency index); those of the
Rigodium species are listed in the discussion of that
analysis. For autapomorphies of the families for
superfamily Leskeacanae, see Buck and Vitt (1986).
Characters for Analysis of Representative Genera of
Out of numerous possible features examined, only those
with the potential for elucidating phylogenetic
relationships (i.e., those potential synapomorphies) were
included in the PAUP analyses. Table 3 represents the basic
data set for the three analyses of the ten representative
genera of superfamily Leskeacanae (plus two outgroups). The
18 characters are listed numerically and discussed briefly
1. Development of the stipe (0 = well-developed). As
discussed in the section on morphology, the stipe is the
unbranched part of the lower stem and is an indication of
the development of an arborescent habit type.
2. Differentiation of secondary orders of branching (0
= differentiated branching). Some genera, such as Thuidium
and Thamnobryum are characterized by secondary (and even
tertiary) branching, while in others, such as Leskea, the
primary branches do not ramify.
3. Organization of the axes into stems vs. branches (0
= well-organized stems and branches). In Leskea and
Pseudoleskea, for example, the few branches that do occur
are not very well-developed and are not distinguishable from
the main stems. In Thuidium, or even Bryohaplocladium (with
essentially no secondary branching), the branches are
numerous and well-developed.
4. Presence and types of paraphyllia (0 = no
paraphyllia). Riqodium lacks these structures, which are
discussed in detail under morphology. The three forms of
paraphyllia filamentouss, branched and foliose) are numbered
(but not ordered) differently in the matrix (see Table 3).
Note that a genus may be characterized by more than one
5. Presence of pseudoparaphyllia (= 0).
Pseudoparaphyllia, also absent in Ricodium, are discussed
with paraphyllia in the section on morphology.
6. Dimorphic stem and branch leaves (0 = no
dimorphism). In certain genera (e.g., Rigodium and
Thuidium), the stem leaves are broadly ovate at the base and
taper to an acumen, but the branch leaves are narrowly ovate
and acute. Pleuroziopsis, with very broadly ovate and blunt
stem leaves and ovate, deeply toothed branch leaves, here is
considered to have a different type of leaf dimorphism.
7. + Subulate stem leaves (0 = non-acuminate leaves).
These stem leaves are ovate at the base and more or less
abruptly taper to an acumen (e.g., Claopodium and Rigodium).
This feature is related to character 7, but not all genera
with this stem leaf shape have dimorphic stem and branch
leaves (e.g., Echinodium).
8. Reduced costa (0 = costa present). A very weak to
absent costa is present in genera such as Heterocladium (as
well as certain species of Rigodium).
9. Quadrate alar cells in rows (0 = alars not
differentiated). Pterigynandrum, Leskea and Pseudoleskea
share this feature, but in the other genera, the alar region
is either undifferentiated or not differentiated in this
10. Prorulose midlaminar cells (0 = cells non-
prorulose). A distinction is made here between papillose
("11" below) and prorulose cells, in which the end walls
project dorsally, sometimes even forming well-developed
papillosities (prorulae) as in Pteriqynandrum and Rigodium.
11. Papillose leaf cells (0 = smooth leaf cells). A
loose interpretation of "papillose" is applied here,
including mammillose (low papillose) and multiple papillate
forms. Mammillose cells bulge in the lumen as well as in
the wall. Basically, all of these wall projection types
occur centrally in the cell.
12. Autoicous sexual condition (0 = dioicous). This
indication of sexuality was included in the analysis as a
few taxa (e.g., Bryohaplocladium and some species of
Helodium) differed from the rest of the group (dioicous).
13. Lack of cilia (0 = cilia present). This character
is an indication of a reduced hypnalean endostome, as found
in Leskea, Pseudoleskea, and Pteriqynandrum.
14. Reduced ornamentation of exostome (0 = standard
exostome ornamentation). As discussed by Buck and Vitt
(1986), the standard hypnalean exostome tooth is cross-
striolate below and papillose above; teeth of Leskea and
Pseudoleskea demonstrate irregularly striolate to entirely
15. Erect capsules (0 = inclined to horizontal
capsules). (See below).
16. Symmetric capsules (0 = asymmetric capsules).
Erect and symmetric capsules may be correlated characters.
A typical hypnalean capsule is horizontal to inclined and
asymmetric in shape.
17. Reduction of the annulus (0 = well-developed
annulus). In Leskea and Pseudoleskea, the annulus is
reduced to absent.
18. Conic operculum (0 = rostrate operculum).
Opercula are either rostrate (e.g., Rigodium) or lack the
beak (conic), as in Leskea.
Results of Analyses of Genera
Three analyses were evaluated using the basic matrix in
Table 3. In one analysis, Thamnobryum functioned as the
outgroup (Pleuroziopsis deleted), and in the second,
Pleuroziopsis was the designated outgroup (Thamnobryum
omitted). In the third analysis, both genera were included
as outgroups. Thus, certain characters are polarized
differently according to the particular outgroup(s) chosen.
Only one most parsimonious tree (50 steps, CI=0.760;
Fig. 17) was generated when Thamnobryum was used as the
outgroup. Echinodium is basal (as opposed to terminal in
Buck and Vitt's cladogram, Fig. 16), with Riqodium
positioned between it and Thuidium. In addition, Leskea-
Pseudoleskea-Pteriqynandrum, basal in Fig. 16, are the most
derived groups here. The cladogram also does not support
Buck and Crum's (1990) transfer of Bryohaplocladium and
Claopodium from Thuidiaceae to Leskeaceae, as inclusion of
these two genera with Leskea and Pseudoleskea in one family
would result in a polyphyletic group. Bryohaplocladium and
Claopodium appear phylogenetically closer to Leskea than to
Thuidium, however. Likewise, Pterigvnandrum and
Heterocladium (Pterigynandraceae; Buck and Crum, 1990) are
not shown as sister groups. The several homoplasies on the
lineage leading to Pteriqynandrum, however, may indicate
problems with its placement in this cladogram.
Thirteen characters (1, 2, 5, 6, 7, 9, 11, 13, 14, 15,
16, 17, 18) do not exhibit parallelism, although reversals
(in 5, 6, 7, 14, 11) and polymorphism (5, 11, 15, 16, 18; in
multistate taxa) occur. Also, six of these characters (9,
13, 15, 16, 17, 18) are associated with the Ptericvnandrum-
Rigodium and Echinodium (and other taxa; see Fig. 17)
share characters 7 acuminatee leaves) and 11 (papillose
cells); the synapomorphy of lack of pseudoparaphyllia (5)
and dimorphic leaf shape (6) link Rigodium to Thuidium (and
other taxa). The Rigodium lineage is characterized by
prorulose cells (10, a feature showing homoplasy), and the
polymorphic features of the weak costa (8) and papillose
cells (11), change from 0->1,0 and 1->1,0, respectively.
In the second analysis (Pleuroziopsis as outgroup), the
results are much less resolved; 27 equally parsimonious
trees (53 steps, CI=0.717) were discovered. The consensus
tree (Fig. 18B) is basically polytomous, although
Pteriqynandrum, Leskea, and Pseudoleskea are established as
a monophyletic group. However, one of the 27 trees is
identical in topology to the cladogram derived with
Thamnobryum as the outgroup (Fig. 17), and in many trees,
(e.g., Fig. 18A), Echinodium is basal within the group, with
Ricodium phylogenetically adjacent.
With Thamnobrvum and Pleuroziopsis functioning as a
combined outgroup, 33 most parsimonious trees were generated
(54 steps, CI=0.704). The use of both taxa simultaneously
to root cladograms was problematical as one or the other of
these genera appears within the ingroup in several of the
trees (i.e., the tree could not be rooted so that the
ingroup was monophyletic). This issue weakens the validity
of using both these taxa as outgroups. However, several of
the trees (where the combined Pteriqynandrum-Thamnobryum
does appear as the outgroup) are similar in topology to
those discussed above (e.g., Fig. 17) and have Echinodium in
a cladistically basal position, followed by Riqodium and
The consensus tree of the previous analysis (Fig. 18B)
indicates that more detailed phylogenetic investigations
(with more genera) are needed to better define the
relationships of the families within the Leskeacanae. The
present analyses do support maintaining Rigodiaceae as a
monotypic family, since inclusion with Thuidiaceae
(Thuidium) would result in a paraphyletic family.
Characters for Rigodium Species
The matrices of Tables 4 and 5 are the data sets used
in the analyses of Rigodium species. Eight characters were
polarized using Echinodium as the outgroup. Although the
number of OTUs differ (see discussion following), the number
of characters remained constant for both analyses. Six
characters are qualitative, and two are quantitative (one
continuous and one discontinuous). The problems in forming
taxonomic characters from measurements are summarized in
Almeida and Busby (1984). The approach in this revision
(see Fig. 19A and B) involves the traditional method of
scanning the full range of the material and partitioning the
scale into classes of varied range. The character states
are, thus, somewhat arbitrarily delimited. Only the
characters with an obvious gap (number of cells in the
intramarginal band, Fig. 19A; stem leaf decurrency/total
leaf length, Fig. 19B) were used in the cladistic analysis,
although three other characters (intramarginal vs.
midlaminar cell length, Fig. 19C; stem leaf length/width,
Fig. 19D; and stem leaf acumen length/length from point of
insertion, Fig. 19E) show basic trends. These three latter
features are discussed under the appropriate species
discussions following the diagnoses in this revision.
The following lists the characters as their derived
state ("1" in Tables 4 and 5; character 6 has two derived
states, "1" and "2.")
1. Rooting at tips. As discussed in the morphology
section, several species of Rigodium (e.g., R. toxarion)
develop rhizoid clusters at the tips of stem and branches
and thereby form new plants.
2. Loss of well-differentiated stipe. Two species (R.
implexum and R. pseudo-thuidium) lack the arborescent habit
and the associated well-developed stipe (lower unbranched
portion of the stem).
3. Right angle branching. In R. brachypodium var.
tamarix (Fig. 38A), B. implexum (Fig. 44G), and R. pseudo-
thuidium (Fig. 46A), the primary branches are spreading,
evenly spaced and arise at right angles to the stem.
4. Decurrent stem leaves. Stem leaves were ranked as
"decurrent" when the stem leaf decurrency/total leaf length
ratio exceeded 8% (Fig. 19B). Note that a percentage
greater than 14 is an autapomorphy for R. adpressum.
5. Uneven midlaminar cell walls. In R. toxarion, (as
in Echinodium), these cell walls are not very porose (Fig.
27J), compared to the other species with conspicuously
uneven walls (e.g., R. pseudo-thuidium, Fig. 46M).
6. Visibly prorulose midlaminar cells. In R.
toxarion, the cells are prorulose, but not easily
discernible (Fig. 27J), while in R. adpressum, R. implexum
and R. pseudo-thuidium these cells are noticeably thickened
at the end walls (e.g., Fig. 46M). In R. brachypodium (both
varieties) the end walls project as dorsal papillae
(prorulae; Fig. 10C and D). In the matrices, the thickened
but not papillose condition is indicated as "1," and the
papillose extreme, as "2." This does not, however, mean
that condition "2" is necessarily more derived that "1;"
other than the fact that "0" is basal (outgroup comparison),
the actual sequence of events (i.e., 0->1->2, 0->2->1, or
1<-0->2) is unknown here (see discussion of results).
7. Seven or greater cell rows in intramarginal band.
A natural division in the number of cell rows is apparent at
seven cells (Fig. 19A), with R. implexum and R. pseudo-
thuidium both characterized by this derived condition..
8. Extremely thickened cell walls of intramarginal
band. In E. toxarion (Fig. 27K) the intramarginal band is
barely visible, even in cross section (Fig. 271). In the
other four species, the walls are extremely incrassate and
easily distinguished from the midlaminar cells, even in
surface view (e.g., Fig. 46L).
Results of Analyses of Rigodium Species
The data sets (Tables 4 and 5) for the two analyses
were identical except for the configuration of R.
brachypodium. In the first analysis, this species was split
into its two varieties, R. brachypodium var. brachypodium
and R. brachypodium var. tamarix, in order to test the
monophyly of the species (Table 4). In the second
examination (Table 5), the species was assumed to be
monophyletic with two polymorphous character states (3,
right angle branching; 4, decurrent stem leaves).
Figure 20 is the single most parsimonious tree (11
steps, CI=0.818) for Riqodium species with the two varieties
of R. brachypodium designated as separate OTUs. Ricodium
toxarion is basal, followed by R. brachypodium and R.
adpressum, and R. pseudo-thuidium and R. implexum are
derived sister-species. Of interest is that R. brachypodium
is not monophyletic here, but paraphyletic.
The only parallelism involves character 3 (right angle
branching) for R. brachypodium var. tamarix and the R.
implexum-R. pseudo-thuidium clade, which may reflect that
the ramification is actually different in these two
instances. In R. brachypodium var. tamarix the branches are
regularly pinnate (Fig. 38A), while the branching of the
other two species is irregularly pinnate. In fact, the
habit type of R. implexum (Fig. 22A) may have been derived
from a form like R. pseudo-thuidium with several innovations
arising from the main stem (Fig. 22B); see also discussion
under R. pseudo-thuidium).
The only reversal in the cladogram is where "rooting at
the tips" (1) was lost for the R. implexum-R. pseudo-
thuidium clade, possibly because this feature is correlated
with the loss of the aborescent or frondose habit. This
analysis also suggests that the direction within character 6
(degree of prorulosity) is 0->2->1, i.e., the less prorulose
state (1) is secondarily derived from the extreme papillose
In the second analysis, R. brachypodium was considered
to be a monophyletic multistate taxon (polymorphic
characters 3 and 4; Table 5). Two equally parsimonious
cladograms were generated (12 steps, CI=0.917; Fig. 21A and
B), with one tree (Fig. 21B) equivalent to the strict
consensus tree. In contrast to the previous analysis, where
R. adpressum is more derived than R. brachypodium (which is
paraphyletic), the position of the former species here is
either phylogenetically intermediate between R. toxarion and
E. brachypodium (Fig. 21A) or unresolved (Fig. 21B). The
other portions of the tree (R. toxarion basal; R. implexum-
R. pseudo-thuidium terminal sister-taxa) are supported as in
the previous analysis.
Within the multistate E. brachypodium, homoplasy is
indicated for characters 3 (right angle branching) and 4
(decurrent stem leaves). Also, the direction of evolution
for character 6 is towards increasing degree of prorulosity
(0->1->2), instead of the secondarily derived reduction in
the previous analysis.
For both analyses, character 1 (rooting at tips--which
reverses within the terminal portion) is a defining feature
of Rigodium. In addition to this feature, autapomorphies of
the genus (i.e., synapomorphies of its species) include the
presence of a differentiated intramarginal band of cells and
extremely incrassate cells. Thus, the genus is clearly
Taxonomic Philosophy Concerning Species
As suggested in Budd and Mishler (1990), the working
definitions of species used by taxonomists are, in general,
either phenetic or basically cladistic. In this revision, a
species was defined primarily as a phenetically cohesive
unit that is separated from other similar entities by a
consistent morphological gap. Monophyly cladisticc
approach) was examined secondarily in the analyses discussed
above. Rigodium toxarion (the basal species) is
metaphyletic (Donoghue, 1985; Mishler, 1985), as no
autapomorphies define it. Rigodium adpressum, R. implexum
and R. pseudo-thuidium are monophyletic, each distinguished
by the following autapomorphies: (1) R. adpressum: appressed
leaves, strongly revolute leaf margins, decurrency of stem
leaf greater than 14% of total leaf length (Fig. 19B), low
central papillae in some cells of the stem leaf decurrency,
and intramarginal cells shorter than the midlaminar cells
(Fig. 19C); (2) R. pseudo-thuidium: reduction of secondary
and loss of tertiary branching and loss/reduction of stem
leaf costae; and (3) R. implexum: free-living, terrestrial
"tumbleweed" habit with extremely wiry axes and profuse
branching. As discussed above, R. brachypodium may be
monophyletic or paraphyletic. Since the strong character 6
(end walls with prorulae) and intermediate habit forms
(detailed in the discussion of R. brachypodium var.
brachypodium) link the two varieties, from a practical
standpoint this taxon is considered as a single species in
this revision, and it is considered probably monophyletic.
A variety here is defined as a monophyletic (or
metaphyletic) group within a species that is separated from
other such entities by a small morphological gap (Wilken &
Hartman, 1991). Thus, the variety in the traditional sense
of an allopatric race (Mayr, 1969), i.e., having one to few
conspicuous differences associated with a certain
geographical range, is not applied in this revision (see
Stuessy, 1990, for discussion on infraspecific categories).
The category of variety is applied within two species, R.
toxarion and R. brachvyodium. Although both varieties of R.
toxarion are sympatric, the traditional varietal concept
somewhat applies since R. toxarion var. robustum is
restricted to the Juan Fernandez Islands. This variety is
additionally defined by the autapomorphy of narrow branch
leaves (see details under discussion of R. toxarion var.
robustum), while R. toxarion var. toxarion is metaphyletic.
As discussed above, the two varieties of R. brachypodium
here are considered to comprise one species due to the
presumed synapomorphy of prorulae, as well as intermediates
in habit type. Rigodium brachypodium var. tamarix is
defined by the autapomorphy of the habit type (elongated
stems with regularly pinnate branching), while R.
brachypodium var. brachypodium is considered metaphyletic.
Table 2. A list of the synapomorphic characters for the
order Hypnales as featured in the cladogram (Fig. 16)
modified from Buck and Vitt (1986). The characters
indicated by the authors as symplesiomorphic and
autapomorphic are deleted here, hence the
discontinuities in the numbering system on the
cladogram and for their characters listed below.
1. Peristome hypnoid; capsules horizontal, asymmetric; leaf
2. Exostome teeth long; gametophores dendroid; endostome
segments gaping; leaves coarsely serrate
3. Leaf cells thin-walled; alar cells thin-walled, quadrate
5. Leaf cells long
7. Opercula + rostrate; leaves with thickened margins
11. Exostomial shoulder well-developed
12. Leaf cells + papillose; alar cells reduced; leaf cells
secondarily short; plants xerophytic
13. Leaves subulate
14. Capsules erect; costa weak; paraphyllia reduced;
16. Stem leaves differentiated; branching well-developed
21. Leaf cells long
22. Leaves varying around lanceolate
25. Peristome yellow-brown; costa poorly developed; leaf
26. Alar cells small; capsules short; substrate of wood and
29. Alar cells covering costal base; pseudoparaphyllia
30. Costal spine present
34. Leaf cells short; peristome reduced; plants epiphytic
37. Costa lost
40. Exostome shoulder amplified; opercula long-rostrate;
alar cells amplified (shape)
45. Plants flattened
Table 3. Data matrix for the cladistic analysis of selected
genera of the superfamily Leskeacanae. "?" = missing
data. Polymorphous characters are indicated as: a =
1,2,3, b = 1,2; c = 0,2; d = 0,1. Thamnobryum and
Pleuroziopsis functioned as outgroups in the analyses.
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8
Thamnobryum 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Pleuroziopsis 0 0 0 0 1 0 0 1 0 1 0 0 1 0 0 0 ? ?
Bryohaplocladium 1 1 0 a 1 1 1 0 0 1 1 0 O O O 0 d
Claopodium 1 1 0 c 1 d 1 0 O 0 1 0 O O O O O O
Echinodium O0 1 0 O 0 1 0 O 0 d 0 O O O O O 0
Helodium 1 1 0 a 1 O 1 0 0 1 1 d O O O O O O
Heterocladium 1 1 0 b d 1 1 1 0 1 1 0 O O O 0 d
Leskea 1 1 1 b 1 0 0 0 1 0 1 1 1 1 1 1 1 1
Pseudoleskea 1 1 1 b 1 0 1 0 1 0 1 0 1 0 dd 1 1
Pterivqnandrum 1 1 1 0 0 0 0 1 1 1 0 0 1 1 1 1 0 0
Riqodium O O O0 1 1 1 d 0 1 d O O O O O O0
Thuidium 1 0 0 a 1 1 1 0 O 0 1 0 O O O O O O
FIG. 17. Most parsimonious tree for representative
genera of the superfamily Leskeacanae using Thamnobryum as
the outgroup. Characters are listed in the text; for the
character states see data matrix (Table 3).
o 0 0 0 -
a =1,2,3 c = 0,2
b=1,2 d =0,1
FIG. 18. Representative trees for the genera of the
superfamily Leskeacanae using Pleuroziopsis as the outgroup.
A. Sample tree (out of 27 equally parsimonious cladograms).
Characters are listed in the text; for the character states
see data matrix (Table 3). B. Consensus tree.
. o 0 o 0 0 L- .
S C) r) D
0 "-C r- 0 -C C. _. Q.
1a2 6d' c8,11 4b1' 14
18d \ 4 12 b' .15d',16d'
a4a' (2 1718
8 1 \ \12d' 10'
4a' 5d' 7,13
8d' 10' 18d' 3'15',16'
3' 1 1d' 10'
4(0-2) polymorphic characters
a = 1,2,3 c = 0,2
o o -oo r- o o- o "
S 0 _? M.
FIG. 19. Morphological Trends in Rigodium species. A.
Number of cell rows in the intramarginal band of stem
leaves, showing division at 8 cells. B. Range of variation
in stem leaf decurrency length/total leaf length, showing
gaps at 8 and 13. C. Range in intramarginal and marginal
cell lengths. D. Range in stem leaf length/width. E.
Range in stem leaf acumen length/leaf length from point of
insertion. TOX = R. toxarion; BRAB = R. brachypodium var.
brachypodium; BRAT = R. brachypodium var. tamarix; ADP = R.
adpressum; PSE = E. pseudo-thuidium; IMP = R. implexum.
Asterisks (*) in B and C indicate autapomorphies (for R.
adpressum). Character groupings depicted in A and B were
used in cladistic analyses.
t--- m-- r
4 6 8 10
Number of Cells
5 10 15 20
Decurrency L/Total Leaf L
-.-- .-- -
Cell Length (um)
0.75 1.25 1.75
Stem Leaf L/W
20 o 0 60
Acumen L/Leaf L
- -' -- --'- --- -- ---- ----- ---- --- -- ----
Table 4. Data matrix for the cladistic analysis of
Rigodium species where the varieties of R.
brachypodium are treated as separate OTUs.
Echinodium functioned as the outgroup in the
R. brachypodium var. brachypodium
R. brachypodium var. tamarix
1 2 3 4 5 6 7
0 0 0 0 0 0 0
1 0 0 0 0 0 0
FIG. 20. Most parsimonious tree in analysis of
Rigodium species with the two varieties of R. brachypodium
("brat" and "brab") treated as separate OTUs. For
characters see the text; for the character states see Table