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_OCCASIONAL PAPERS_
of the
MUSEUM OF NATURAL HISTORY
The University of Kansas
Lawrence, Kansas
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NUMBER 1 APRIL 29, 1971
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A SYNOPSIS OF NEOTROPICAL HYLID FROGS,
GENUS _OSTEOCEPHALUS_
By
LINDA TRUEB[1] AND WILLIAM E. DUELLMAN[2]
[1] Research Associate, Division of Herpetology, Museum of Natural
History, University of Kansas.
[2] Curator, Division of Herpetology, Museum of Natural History,
University of Kansas.
When we initiated a study of the herpetofauna at Santa Cecilia in
Amazonian Ecuador in 1966, we were immediately confronted with many
kinds of animals that we could not identify with the existing
literature. Comparisons of our specimens with those preserved in other
museums resolved some of the problems, but many identifications could be
made only after study of type specimens; even then some determinations
remained questionable. We now find that in order to prepare a meaningful
account of the herpetofauna of Santa Cecilia, we must complete several
taxonomic studies, the limits of which extend far beyond eastern
Ecuador. Because of our interests in hylids we have begun our studies on
these frogs.
One of us (Trueb, 1970a) studied the cranial osteology of casque-headed
hylid frogs and redefined the genus Osteocephalus but did not determine
the number of species in the genus. Our work in Amazonian Ecuador
resulted in the discovery of the sympatric occurrence of three species
at each of two localities; one of these species was found with a fourth
species at another locality. Study of museum specimens confirmed the
recognition of these four species in the Amazon Basin and lower
Amazonian slopes of the Andes. A fifth species from Bolivia and Peru
also is included in the genus. Examination of museum specimens has
provided data on the geographic variation in, and distribution of, the
five species. However, our conclusions pertaining to some populations
need substantiation, because we have been hampered by inadequate
material from areas beyond Ecuador. More than half of the 905 specimens
of _Osteocephalus_ are from Ecuador, a relatively small part of the
total range of the genus.
In this paper we are presenting a taxonomic review of the genus
_Osteocephalus_; of necessity our study has been at the alpha level. We
have utilized all of the usual external characters, as well as
osteological features in our definitions of the species. Tadpoles and
mating calls are available for only one species, _O. verrucigerus_
(Trueb and Duellman, 1970); these and other important systematic
characters, such as karyotypes, are not available for the group at this
time. Our tendency has been to take a conservative view of species; thus
it is doubtful that any subsequent worker will recognize fewer species
in the genus. Our observations on these frogs in Amazonian Ecuador are
presented in a final section of this paper.
ACKNOWLEDGMENTS
For the loan of specimens or for the provision of working space in their
respective institutions, we are indebted to James E. Boehlke, Werner C.
A. Bokermann, F. W. Braestrup, Nelly Carrillo de Espinoza, Osvaldo R. da
Cunha, Josef Eiselt, M. J. Fouquette, Jr., Alice G. C. Grandison, Jean
Guibe, Birgitta Hansson, Walter Hellmich, M. J. Hoogmoed, Robert F.
Inger, Konrad Klemmer, Jean Lescure, Alan E. Leviton, Clarence J. McCoy,
Robert H. Mount, Charles W. Myers, Umberto Parenti, Guenther Peters,
James A. Peters, William F. Pyburn, Juan A. Rivero, Dorothy M. Smith,
Paulo E. Vanzolini, Greta Vestergren, David B. Wake, Charles F. Walker,
Ernest E. Williams, and Richard G. Zweifel.
Study of specimens in European museums was made possible by a grant (No.
5063) from the Penrose Fund of the American Philosophical Society. Field
work in Ecuador was partially supported by grants from the Watkins Fund
of the Museum of Natural History, University of Kansas. At our base camp
at Santa Cecilia, Ecuador, we enjoyed the hospitality of Ing. Ildefonso
Munoz B. Transportation in Ecuador was generously provided by the Texaco
Petroleum Company. During the course of our field work Stephen R.
Edwards and Thomas H. Fritts contributed directly to our study of
_Osteocephalus_. Michael J. Tyler of the South Australian Museum
provided information on the vocal sac structure. We extend our sincere
thanks to all of these persons for their contributions to our endeavors.
MATERIALS AND METHODS
We have examined 893 preserved frogs, including the type specimens of
all included nominal taxa, 8 skeletons, 1 lot of eggs, and 3 lots of
tadpoles that we refer to the genus _Osteocephalus_; in addition skulls
were removed from five preserved specimens, and radiographs were made of
12 other preserved specimens. We have been fortunate in seeing living
individuals of all species, except _O. pearsoni_, but we have colored
photographs of a living specimen of that species. Figures 1 and 2 were
drawn from projected colored transparencies of living frogs. Terminology
follows that of Duellman (1970b). On the distribution maps solid symbols
indicate localities from which we have examined specimens; open symbols
represent additional locality records based on the literature.
Throughout the text specimens are listed by their catalogue numbers
preceded by the appropriate museum abbreviation, as follows:
AMNH American Museum of Natural History
ANSP Academy of Natural Sciences of Philadelphia
ASU Arizona State University
AUM Auburn University Museum
BMNH British Museum (Natural History)
CAS California Academy of Sciences
CAS-SU Stanford University Collection
(In California Academy of Sciences)
CM Carnegie Museum
FMNH Field Museum of Natural History
KU University of Kansas Museum of Natural History
MCZ Museum of Comparative Zoology, Harvard University
MIZS Museo ed Istituto di Zoologi Sistematico, Universita di Torino
MJP Museo Javier Prado, Lima
MNHN Museum National d'Histoire Naturelle, Paris
MPEG Museu Paraense Emiliano Goeldi, Belem
MVZ Museum of Vertebrate Zoology, University of California, Berkeley
MZUSP Museu de Zoologia, Universidade da Sao Paulo
NHMG Naturhistoriska Museet Goeteborg
NHMW Naturhistorisches Museum, Wien
NHRM Naturhistoriska Riksmuseet, Stockholm
RMNH Rijksmuseum van Natuurlijke Histoire, Leiden
SMF Senckenbergische Museum, Frankfurt
UIMNH University of Illinois, Museum of Natural History
UMMZ University of Michigan Museum of Zoology
UP Universite de Paris
UPR-M University of Puerto Rico, Mayagueez
UTA University of Texas, Arlington
USNM United States National Museum
UZM Universitets Zoologiske Museum, Copenhagen
WCAB Werner C. A. Bokermann, Sao Paulo, Brasil
ZMB Zoologisches Museum Berlin
ZSM Zoologisches Sammlung Muenchen
HISTORICAL RESUME
Because of the taxonomic confusion that has surrounded the generic name
_Osteocephalus_ and two of the species (and their synonyms), we present
a brief resume of the taxonomic history of the group.
Among the amphibians sent to the Museum National d'Histoire Naturelle in
Paris by a Monsieur Leprieur in French Guiana was a single female
specimen of a moderately large hylid having a well-ossified skull and
smooth dorsal skin. This specimen escaped from the covetous eyes of
Johann Tschudi, who prematurely named several species on the basis of
specimens in Paris, and survived without an epithet until Dumeril and
Bibron (1841) proposed for it the name _Hyla leprieurii_. The
description of the species is fairly detailed, but the specimen was not
illustrated. This is the earliest trivial name now associated with
_Osteocephalus_.
Fitzinger (1843) in his generic synopsis of amphibians and reptiles
proposed the generic name _Osteocephalus_ but did not associate a
specific name with the genus. Consequently, _Osteocephalus_ Fitzinger,
1843, is a _nomen nudum_. Franz Steindachner followed Leopoldo Fitzinger
at the Naturhistorisches Museum in Vienna, where he had access to
Fitzinger's notes and, of course, the important collections housed in
that museum. Steindachner (1862) named two species of _Osteocephalus_ on
the basis of Brasilian specimens collected by Johann Natterer. Both
species were named in the same publication; _O. taurinus_ appeared on
page 77, and _O. favolineatus_, on p. 80. This is the earliest
association of the generic name _Osteocephalus_ with a specific name and
a description, both of which satisfy the Code of Zoological Nomenclature
for generic availability. Therefore, Steindachner is the authority for
the generic name _Osteocephalus_, which has _O. taurinus_ as the type
species by original designation. It is not possible to determine whether
or not Steindachner's usage of _Osteocephalus_ was the same as that
intended by Fitzinger 19 years earlier.
Steindachner (1862) gave reasonably good descriptions of his two new
species and provided excellent illustrations of the two specimens, both
large females. Apparently impressed by the similarities between
_Trachycephalus nigromaculatus_ Tschudi, 1838, and _Osteocephalus
taurinus_, Steindachner (1867) used the combination _Trachycephalus
(Osteocephalus) taurinus_. This ambiguous usage for the 1860's
precludes our determining if Steindachner was in effect synonymizing
_Osteocephalus_ with _Trachycephalus_ or whether he was placing
_Osteocephalus_ in a subgeneric status. Steindachner (1867) did not
mention _O. flavolineatus_; perhaps by that time he had concluded that
_flavolineatus_ was only a color morph of _taurinus_.
Cope (1867) placed _Hyla leprieurii_ in the genus _Hypsiboas_ Wagler,
1830. Cope (1874) named _Osteocephalus planiceps_ from Nauta, Peru. The
single specimen was among the collections made by the Orton Expedition
to the upper Amazon Basin and was deposited in the Academy of Natural
Sciences in Philadelphia.
Boulenger (1882) placed both _Osteocephalus_ and _Trachycephalus_
the synonymy of _Hyla_; he recognized _Hyla taurina_ (with _O.
flavolineatus_ as a synonym), _H. leprieurii_, and _H. planiceps_. In
the same publication Boulenger named _Hyla buckleyi_ on the basis of 10
specimens in the British Museum from Ecuador; in the description he
stated that _buckleyi_ was like _leprieurii_ and _taurinus_ in having
paired lateral vocal sacs. Boulenger held a lasting influence on
taxonomic herpetology, and his generic synonymy of _Osteocephalus_ was
unchallenged until only a decade ago.
Goin (1961) presented a generic synopsis of the genera of hylid frogs,
in which he recognized _Osteocephalus_ and stated: "There are perhaps
eight or ten species of this genus in South America. Certainly
_taurinus_, _britti_, _leprieuri_, _buckleyi_ and _pearsoni_ belong
here. _O. planiceps_ is surely a synonym of _leprieuri_ and I believe
that _garbei_ is as well. The status of such forms as _macrotis_,
_riopastazae_, and _depressa_ has not yet been settled." Goin defined
_Osteocephalus_ as follows: "Males with paired vocal pouches, one at
each angle of the jaw; derm of head not co-ossified with skull but roof
of skull exostosed." Trueb (1970a) elaborated on Goin's definition and
assuredly included only _O. taurinus_ and _O. leprieurii_ in the genus.
Goin's inclusion of _buckleyi_, _britti_, and _pearsoni_ in
_Osteocephalus_ was the first association of any of these names with
that genus. Duellman (1970a) demonstrated that _Garbeana garbei_
Miranda-Ribeiro, 1926, was a member of the _Hyla rubra_ group. _Hyla
macrotis_ Andersson, 1945, is a _Phrynohyas_. Trueb and Duellman (1970)
determined that _Hyla verrucigera_ Werner, 1901, is the earliest name
for an _Osteocephalus_ displaying striking sexual dimorphism in
coloration and texture of the dorsal skin; _Hyla riopastazae_ Andersson,
1945 (female holotype), and _Hyla orcesi_ Funkhouser, 1956 (male
holotype), were placed in the synonymy of _Osteocephalus verrucigerus_.
_Hyla pearsoni_ Gaige, 1929, is a small species of _Osteocephalus_. Our
findings substantiate Goin's suggestions relative to two other taxa.
_Hyla leprieurii britti_ Melin, 1941, from the Rio Uaupes, Brasil, and
_Hyla depressa_ Andersson, 1945, from the Rio Pastaza watershed,
Ecuador, are members of the genus _Osteocephalus_, but both are synonyms
of earlier names--_leprieurii_ and _taurinus_, respectively. Another
name proposed by Melin (1941), _Hyla (Trachycephalus) vilarsi_ from
Taracua, Brasil, also is placed in the synonymy of _O. taurinus_.
Cochran and Goin (1970) were unaware of the identities of _Hyla
verrucigera_ and _riopastazae_; they used the later name _Osteocephalus
orcesi_ for Colombian frogs that are correctly referred to _O.
verrucigerus_. Although Goin (1961) placed _Hyla buckleyi_ and _H.
pearsoni_ in _Osteocephalus_, Cochran and Goin (1970) recognized a
"_buckleyi_ group" in _Hyla_ that included these two species plus a new
species, _Hyla cabrerai_ from Amazonian Colombia and Brasil (total of
three specimens). Also, these authors named _Hyla carri_ from a single
Colombian specimen. Study of the types of _Hyla cabrerai_, _H. carri_,
and _H. festae_ Peracca, 1904, from Ecuador, reveal that all of these
names are synonyms of _Osteocephalus buckleyi_.
Much of the taxonomic confusion and multiplicity of trivial names is due
to the great amount of color variation in _taurinus_ and to the sexual
dimorphism in the texture of the dorsal skin in all of the species.
The details of variation in these and other characters and our
justifications for the synonymies are given in the accounts of the
species. All of the trivial names that apply to species herein
recognized as members of the genus _Osteocephalus_ are listed in
table 1.
=Osteocephalus= Steindachner, 1862
_Osteocephalus_ Steindachner, 1862:77 [Type
species.--_Osteocephalus taurinus_ Steindachner, 1862, by
original designation]. Not _Osteocephalus_ Fitzinger,
1843:50 (_nomen nudum_).
_Diagnostic Definition._--1) Skull broader than long; 2) dermal roofing
bones of skull well ossified, exostosed, and/or co-ossified in some
species; 3) prenasal and internasal bones absent; 4) parasphenoid alae
posterolaterally oriented; 5) dentigerous processes of prevomers angular
(/--\); 6) vocal sacs paired, posterior, and when inflated protruding
posteroventral or posterolateral to angles of jaws; 7) submentalis
muscle moderate in size and araphic; 8) intermandibularis muscle
undifferentiated and bearing an elongate median aponeurosis; 9)
parotoid glands absent or poorly developed, skin not producing viscous
secretion characteristic of _Phrynohyas_; 10) skin on dorsum tuberculate
in males, smooth in females; 11) tympanum large, 60 percent or more of
diameter of eye; 12) fingers about one-third, toes more than
three-fourths webbed; 13) discs large, round; 14) nuptial excrescences
present in breeding males; 15) inner metatarsal tubercle not modified
for digging; 16) outer metatarsal tubercle absent; 17) tarsal fold weak
or absent; 18) pupil horizontal; 19) palpebrum clear; 20) known tadpoles
having two upper and five lower rows of teeth.
TABLE 1.--Alphabetical Synonymy of the Species of _Osteocephalus_.
Trivial Name, Original Generic Name, Author, Date Current Name
----------------------------------------------------------------------
_britti (Hyla leprieurii)_ Melin, 1941 _O. leprieurii_
_buckleyi (Hyla)_ Boulenger, 1882 _O. buckleyi_
_cabrerai (Hyla)_ Cochran and Goin, 1970 _O. buckleyi_
_carri (Hyla)_ Cochran and Goin, 1970 _O. buckleyi_
_depressa (Hyla)_ Andersson, 1945 _O. taurinus_
_festae (Hyla)_ Peracca, 1904 _O. buckleyi_
_flavolineatus (Osteocephalus)_ Steindachner, 1862 _O. taurinus_
_leprieurii (Hyla)_ Dumeril and Bibron, 1841 _O. leprieurii_
_orcesi (Hyla)_ Funkhouser, 1956 _O. verrucigerus_
_pearsoni (Hyla)_ Gaige, 1929 _O. pearsoni_
_planiceps (Osteocephalus)_ Cope, 1874 _O. taurinus_
_riopastazae (Hyla)_ Andersson, 1945 _O. verrucigerus_
_taurinus (Osteocephalus)_ Steindachner, 1862 _O. taurinus_
_verrucigera (Hyla)_ Werner, 1901 _O. verrucigerus_
_vilarsi (Hyla)_ Melin, 1941 _O. taurinus_
_Content._--As defined here, the genus contains five known species: _O.
buckleyi_ (Boulenger), _O. leprieurii_ (Dumeril and Bibron), _O.
pearsoni_ (Gaige), _O. taurinus_ Steindachner, and _O. verrucigerus_
(Werner).
_Distribution._--The Guianas and Amazon Basin; also in the upper Orinoco
and Magdalena drainages. Most localities are at elevations below 500 m,
but the genus ascends the Amazonian slopes of the Andes to elevations of
about 1800 m.
ANALYSIS OF CHARACTERS
_Size and Proportions._--Frogs of the genus _Osteocephalus_ are moderate
to large hylids. The largest species is _taurinus_, attaining a
snout-vent length of 103.1 mm; the smallest is _pearsoni_, which attains
a length of 54.7 mm. Considerable intraspecific geographic variation
occurs in adult size, especially in _taurinus_. Females of all species
attain a noticeably larger size than males, but no significant
differences are apparent in proportions (Table 2).
TABLE 2.--Comparison of Size and Proportions in the Species of _Osteocephalus_.
(Means are given in parentheses below observed ranges)
========================================================================================================
Species N Snout-vent Tibia Length/ Foot Length/ Head Length/ Head Width/ Tympanum/
Length S-V L S-V L S-V L S-V L Eye
--------------------------------------------------------------------------------------------------------
_O. buckleyi_ [M] 30 37.9-48.1 0.478-0.580 0.375-0.444 0.319-0.357 0.329-0.368 0.608-0.820
(43.3) (0.520) (0.408) (0.343) (0.351) (0.711)
[F] 31 48.6-75.1 0.476-0.599 0.363-0.469 0.310-0.358 0.318-0.367 0.574-0.905
(61.7) (0.553) (0.428) (0.333) (0.348) (0.734)
_O. leprieurii_ [M] 21 41.2-48.4 0.514-0.571 0.383-0.430 0.308-0.357 0.326-0.368 0.652-0.884
(44.7) (0.538) (0.408) (0.335) (0.348) (0.777)
[F] 21 46.6-61.5 0.516-0.592 0.382-0.453 0.314-0.343 0.328-0.363 0.698-0.909
(57.1) (0.539) (0.404) (0.329) (0.349) (0.785)
_O. pearsoni_ [M] 2 45.3-46.2 0.481-0.504 0.404-0.437 0.322-0.335 0.327-0.342 0.660-0.673
(45.8) (0.493) (0.421) (0.329) (0.335) (0.666)
[F] 1 54.7 0.521 0.405 0.318 0.346 0.862
_O. taurinus_ [M] 59 40.3-84.6 0.512-0.576 0.387-0.445 0.296-0.345 0.301-0.355 0.638-0.896
(66.3) (0.541) (0.416) (0.318) (0.324) (0.752)
[F] 45 45.1-103.1 0.520-0.577 0.391-0.448 0.306-0.334 0.308-0.347 0.640-0.817
(75.8) (0.542) (0.420) (0.321) (0.327) (0.758)
_O. verrucigerus_ [M] 11 50.4-54.3 0.494-0.552 0.409-0.442 0.322-0.346 0.328-0.344 0.623-0.804
(53.0) (0.519) (0.427) (0.333) (0.337) (0.730)
[F] 3 63.1-65.8 0.532-0.561 0.435-0.463 0.345-0.347 0.348-0.379 0.692-0.808
(64.5) (0.545) (0.448) (0.346) (0.358) (0.731)
--------------------------------------------------------------------------------------------------------
_Coloration._--All _Osteocephalus_ are predominantly brown frogs usually
with some darker dorsal markings (Figs. 1 and 2). _Osteocephalus
verrucigerus_ has a nearly uniform dark brown dorsum and no distinct
transverse bars on the limbs, whereas all of the other species have
distinct bars on the limbs. The dorsal markings on the body consist of
irregular blotches in _buckleyi_, _pearsoni_, and _taurinus_ but are
narrow transverse marks in _leprieurii_. A narrow middorsal cream or
yellow stripe is present in some individuals of _buckleyi_ and
_taurinus_ but absent in all individuals of the other species. The
flanks are uniform pale tan in _leprieurii_ and uniform reddish brown in
_verrucigerus_; in the other species the flanks are cream to brown with
dark brown or black spots (also dark diagonal marks in some _buckleyi_).
A creamy white anal stripe is present in some specimens of _leprieurii_
but absent in all individuals of other species.
The postocular region, encompassing the tympanum, is dark brown in most
specimens. In adults of _pearsoni_ and _taurinus_ the upper lips are
dark brown. A pale cream or tan suborbital spot is present in _pearsoni_
and in some _taurinus_; in some specimens of _taurinus_ the suborbital
spot is expanded posteriorly forming a labial stripe on the posterior
part of the lip. The labial markings of _verrucigerus_ are similar to
the latter pattern, except that in females a distinct, light labial
stripe extends the length of the lip. _Osteocephalus leprieurii_ has a
distinct, broad, pale labial stripe. The lips are barred cream and dark
brown in _buckleyi_.
The venter is uniform creamy white or pale tan in _leprieurii_, uniform
white in some _buckleyi_ (most males), and uniform tan in some
_taurinus_. The other species and some individuals of _taurinus_ and
_buckleyi_ (most females) have dark ventral markings. These markings are
most distinctive in _verrucigerus_, in which the venter is white with
bold black mottling and spots (Fig. 3c). Those individuals of _taurinus_
having ventral markings usually have indistinct, diffuse brown spots
on the throat and chest (Fig. 3b). _Osteocephalus pearsoni_ is
characterized by a fine brown reticulation on the venter and on the
anterior and posterior surfaces of the thighs in adults (Fig. 3a).
Individuals of _buckleyi_ that have ventral markings vary between the
patterns illustrated for _pearsoni_ and _taurinus_ (Figs. 3b and c).
Ontogenetic change in coloration is slight or non-existent in
_buckleyi_, _pearsoni_, and _taurinus_, except that juveniles lack
ventral markings. A dark blotch on the back and distinct transverse bars
on the limbs are evident in juveniles of _verrucigerus_; these markings
are obscured in the adults. Juveniles of _leprieurii_ are olive-brown
with yellow dorsolateral stripes; the transverse dark marks,
characteristic of the adults, appear before the stripes are lost.
[Illustration: FIG. 1. Species of _Osteocephalus_: Top. _O.
pearsoni_, KU 136312, [M]; Middle. _O. buckleyi_, KU 123172,
[M]; Bottom. _O. verrucigerus_, KU 123177, [M]. x1.5.]
[Illustration: FIG. 2. Species of _Osteocephalus_: Top. _O.
leprieurii_, KU 126611, [F]; Bottom. _O. taurinus_, KU 126648,
[M]. x1.]
[Illustration: FIG. 3. Diagrammatic views of ventral color patterns
in _Osteocephalus_: a. _O. pearsoni_, UMMZ 57533, [M]; b. _O.
taurinus_, USNM 166037, [M]; c. _O. verrucigerus_, KU 123185, [F].]
_Skin._--The dorsal skin of all males of _Osteocephalus_ is tuberculate
to varying degrees, whereas the dorsal skin of females is smooth, or
nearly so (Fig. 4). _Osteocephalus verrucigerus_ differs from other
members of the genus by the presence of numerous, large tubercles
bearing keratinized tips. The tubercles of _leprieurii_ are numerous and
spinous but much smaller than those of _verrucigerus_; those of
_taurinus_ are spinous but less numerous than in _leprieurii_.
_Osteocephalus buckleyi_ has a mixture of large and small, non-spinous
tubercles, and _pearsoni_ has only a few, small, scattered, non-spinous
tubercles. Fleshy tubercles occur on the eyelids and supratympanic fold
in females of _buckleyi_; a few small tubercles are present on the back
of females of _pearsoni_, whereas the dorsal skin in females of the
other species is smooth. The skin on the flanks of both sexes of
_buckleyi_ is weakly areolate; in the other species the flanks are
smooth. The skin on the top of the head in _taurinus_ is rugose as a
consequence of co-ossification. In all species the anal opening is
directed posteriorly at the upper level of the thighs.
_Hands and Feet._--The feet of _Osteocephalus_ are fully webbed or
nearly so. Webbing between fingers one and two is basal in all species.
Webbing between fingers two, three, and four is most extensive in
_taurinus_, in which the three fingers are about one-half webbed (Fig.
5). _Osteocephalus buckleyi_, _pearsoni_, and _verrucigerus_ have
reduced webbing between fingers two and three, and _leprieurii_ has
reduced webbing between fingers two, three, and four. All members of the
genus have well-developed subconical subarticular tubercles on the
fingers and toes; there is a tendency for the distal tubercle on the
fourth finger to be weakly bifid. Palmar and plantar supernumerary
tubercles are well developed in _taurinus_, moderately developed in
_buckleyi_, _leprieurii_, and _pearsoni_, and barely evident in
_verrucigerus_. All of the species have a noticeable fold on the wrist
and enlarged prepollices, bearing horny nuptial excrescences in breeding
males. The prepollex is least enlarged in _buckleyi_. Outer metatarsal
tubercles are absent. The inner metatarsal tubercle is moderately well
developed and ovoid in _leprieurii_ and _pearsoni_; it is elliptical and
flat in the other species. Tarsal folds are absent in all species except
_verrucigerus_, in which the folds are barely evident.
[Illustration: FIG. 4. Segments of dorsal skin of males of
_Osteocephalus_ showing size and arrangement of tubercles:
a. _O. verrucigerus_, KU 123183; b. _O. taurinus_, USNM 166033;
c. _O. leprieurii_, KU 126616; d. _O. buckleyi_, USNM 165999.
Each square = 1 sq. cm.]
_Cranium._--As a genus, the cranial structure is remarkably uniform and
quite generalized when viewed in the context of the family Hylidae. The
skulls are broad and relatively flat, each being only slightly more
broad than long and about one-third as high as long. In dorsal aspect
the snouts are broadly rounded; the snout of _buckleyi_ is somewhat less
rounded and appears to be slightly longer than the snouts of other
species. This subtle difference relates to the relative narrowness of
the premaxillaries in _buckleyi_.
[Illustration: FIG. 5. Palmar views of hands of males of
_Osteocephalus_: a. _O. buckleyi_, KU 109506; b. _O. leprieurii_,
KU 126627; c. _O. pearsoni_, MCZ 15565; d. _O. taurinus_, KU 126653;
e. _O. verrucigerus_, KU 123177. x4.]
[Illustration: FIG. 6. Skulls of two species of _Osteocephalus_:
a and b. _O. leprieurii_, KU 125961; c and d. _O. pearsoni_,
UMMZ 67465. x3.]
The genus is characterized by well-developed dermal roofing bones and an
unusually large exposure of the sphenethmoid dorsally (Fig. 6). The
conformation of the sphenethmoid exposed dorsally is determined by the
marginal positions of the adjacent, overlapping elements--the nasals and
frontoparietals. Medially the nasals overlap the lateral margins of the
sphenethmoid. Anteromedially, the nasals converge in _leprieurii_ and
_taurinus_, are narrowly separated in _buckleyi_ and _pearsoni_, or are
more widely separated in _verrucigerus_. In all species the nasals
terminate at the anterodorsal corner of the orbit. The frontoparietals
of _buckleyi_, _leprieurii_, and _taurinus_ have an anterolateral
extension, which marginally overlaps the dorsolateral edge of the
sphenethmoid and articulates with the posterodorsal corner of the nasal
in _buckleyi_ and _taurinus_; the bones are narrowly separated in
_leprieurii_. The frontoparietals of _pearsoni_ and _verrucigerus_ have
more extensive median ossification and less extensive anterolateral
ossification. Thus, in those species the posteromedian portion of the
sphenethmoid is obscured, and the lateral margins are partly exposed.
The frontoparietal fontanelle is completely covered in all species,
except _buckleyi_ and _leprieurii_, in which an irregular, median
separation of the frontoparietals exposes a small portion of the
fontanelle. The posterolateral margins of the frontoparietals lie medial
to the epiotic eminences.
Dermal ornamentation, involving the nasals, frontoparietals, and
sphenethmoid, occurs in _taurinus_ and, to a limited extent,
in _pearsoni_. In the latter species marginal portions of the
frontoparietals, the dorsal surfaces of the nasals, and the
posteromedial part of the exposed sphenethmoid are slightly exostosed,
resulting in an open, reticulate pattern of dermal sculpturing of
exceedingly low relief (Fig. 6c). _Osteocephalus taurinus_ is
characterized by casquing, co-ossification, and a rather intricate
pattern of dermal sculpturing, which was described in detail and
illustrated by Trueb (1970a).
The squamosals of all species are moderately large structures having
otic plates that overlie the lateral portion of the cristae paroticae.
The posterior rami are short; the zygomatic rami of all species, except
_taurinus_, extend slightly more than one-half of the distance to the
maxillary. In _taurinus_ the zygomatic ramus extends nearly to, or
articulates with, the maxillary.
The maxillary arches are complete and relatively robust. The alary
processes of the premaxillaries are vertically oriented in _leprieurii_,
_pearsoni_, and _taurinus_ and very slightly inclined posteriorly in
_buckleyi_ and _verrucigerus_. The maxillaries are uniformly
characterized by the absence of postorbital processes and by the
presence of preorbital processes that articulate with the maxillary
processes of the nasals. The partes facialae of the maxillaries are
moderately developed in all species, except _taurinus_, in which the
pars fascialis tends to articulate with the lateral margin of the nasal
in well-ossified individuals. The partes palatinae are poorly developed
in all species, except _buckleyi_, in which the pars palatina of the
premaxillary is moderately robust.
The pterygoids are uniformly tri-radiate structures. The anterior rami
terminate at about the mid-level of the orbit, and the medial rami
articulate firmly with the anterolateral corner of the otic capsule. The
palatines are well-developed elements bearing ventral ridges; the ridges
are somewhat irregular in _buckleyi_, _taurinus_, and _verrucigerus_ but
smooth in _leprieurii_ and _pearsoni_. The parasphenoids are large
elements characterized by acuminate cultriform processes and
posterolaterally inclined alary processes. The basal areas of the
cultriform processes bear small odontoid protuberances in _buckleyi_,
_taurinus_, and _verrucigerus_, whereas they are smooth in _leprieurii_
and _pearsoni_. The prevomers are remarkably uniform, moderately
well-developed structures. In each species the anterior ramus lies
adjacent to the premaxillary, and the lateral wings form the anterior,
medial, and posteromedial margins of the internal nares. The dentigerous
processes are characteristically large and angular and bear numerous
teeth. The sphenethmoid and otoccipitals are well ossified; a dermal
sphenethmoid is present only in _taurinus_.
[Illustration: FIG. 7. Dorsal views of vertebral columns of two
species of _Osteocephalus_: a. _O. leprieurii_, KU 125962, [F];
b. _O. buckleyi_, USNM 165997, [F]. x2.]
_Vertebral Column._--The cervical cotyles are uniformly widely
displaced. The neural arches are low and non-imbricate. The transverse
processes of the third presacral vertebrae are approximately equal in
width to the sacral diapophyses in all species, except _buckleyi_, in
which the processes of the third presacral are slightly narrower than
the diapophyses. _Osteocephalus buckleyi_ is further distinguished by
the presence of narrow transverse processes on presacrals five through
eight (Fig. 7b); males have narrower processes than do females. The
processes are moderately wide but subequal in width in _pearsoni_,
_taurinus_, and _verrucigerus_, whereas they are nearly equivalent in
width to one another and to the sacral diapophyses in _leprieurii_ (Fig.
7a). The sacral diapophyses of all species are moderately dilated and
posterolaterally inclined. The coccyx bears a distinct dorsal ridge and
has a bicondylar articulation with the sacrum.
_Pectoral Girdle._--The pectoral girdles are fully arciferal and bear
small, cartilaginous omosterna and moderately large cartilaginous
sterna. The coracoids are robust, and the clavicles are strongly arched.
Procoracoid cartilage seems to be absent. The scapulae are large,
longer than the clavicles, and bicapitate proximally. The suprascapulae
are moderately large and well ossified in _leprieurii_ and _taurinus_.
The suprascapula of _verrucigerus_ is poorly ossified, and that of
_buckleyi_ is not ossified.
_Pelvic Girdle._--The ilia of _buckleyi_, _taurinus_, and _verrucigerus_
lack any indication of a crest on the shaft, whereas _leprieurii_ has a
low crest. The dorsal acetabular expansion of the ilia is moderately low
in _taurinus_ and _verrucigerus_, but distinctly lower in _buckleyi_ and
_leprieurii_. The ilia of all species bear low dorsal protuberances. The
ischia of _leprieurii_, _taurinus_, and _verrucigerus_ are moderately
expanded; that of _buckleyi_ is somewhat less expanded dorsally. The
pubis of _leprieurii_, _taurinus_, and _verrucigerus_ are calcified,
whereas that of _buckleyi_ remains cartilaginous.
_Throat Musculature and Vocal Sac Structure._--Tyler (1971) described
the throat myology of _Osteocephalus_. The genus is characterized by a
moderate-sized araphic submentalis muscle and an undifferentiated
intermandibularis having an elongate median aponeurosis. The
intermandibularis and submentalis are completely independent in
_buckleyi_, whereas in the other species there is a small attachment
between these muscles.
According to Tyler (pers. com.), _Osteocephalus_ has three distinctive
types of vocal sac structure which result from differences in the
development of the interhyoideus muscle and the overlying skin. In
_leprieurii_ and _verrucigerus_ the supramandibular portions of the
interhyoideus form a simple tubular, posterolateral extension; there is
no modification of the associated skin. _Osteocephalus buckleyi_ and
_pearsoni_ have more extensive development of the supramandibular
portions of the interhyoideus; furthermore, the associated skin forms a
broad, loose fold extending from the ventromedial surface of the throat
dorsolaterally to the base of the supratympanic fold. Like _buckleyi_
and _pearsoni_, the supramandibular portion of the interhyoideus is much
expanded in _taurinus_. The vocal sac structure of _taurinus_ differs
from that of other members of the genus in that the skin of _taurinus_
forms an everted pouch, which dangles loosely beneath the supratympanic
fold.
KEY TO THE SPECIES OF _Osteocephalus_
1. Inner edge of third finger webbed to mid-length of antepenultimate
phalange; dorsum brown with dark brown spots or median
blotch; skull in adults casqued and co-ossified with prominent
supraorbital flanges _O. taurinus_
Inner edge of third finger webbed to base of antepenultimate
phalange; dorsum plain or marked with dark blotches or transverse
bars; skull in adults smooth or slightly exostosed, lacking
supraorbital flanges 2
2. Skin on flanks areolate; dorsum in males bearing a mixture of
large and small non-spinous tubercles; lips distinctly barred
_O. buckleyi_
Skin on flanks smooth; dorsum in males bearing tubercles of
uniform size; lips not barred 3
3. Dorsal pattern consisting of narrow transverse dark bars; dorsum
in males bearing numerous small spinous tubercles _O. leprieurii_
Dorsal pattern not consisting of transverse bars; dorsal tubercles
large or few in number 4
4. Dorsum uniformly dark brown; venter heavily mottled with
black, especially in females; dorsum in males bearing large,
keratinized tubercles _O. verrucigerus_
Dorsum tan with irregular dark brown blotches; venter cream
with fine brown reticulations; dorsum in males bearing few, small
non-spinous tubercles _O. pearsoni_
ACCOUNTS OF SPECIES
=Osteocephalus buckleyi= (Boulenger)
_Hyla buckleyi_ Boulenger, 1882:362 [Syntypes.--BMNH
1947.2.13.36-39 from Sarayacu, Provincia Pastaza, Ecuador; BMNH
1947.2.13.40-41, 1947.2.13. 43-45 from Canelos, Provincia Pastaza,
Ecuador; BMNH 1947.2.13.46 from "Paitanga" (= Pallatanga),
Provincia Chimborazo, Ecuador (in error); Mr. Buckley collector;
BMNH 1947.2.13.44 here designated as lectotype].
_Hyla festae_ Peracca, 1904:39 [Holotype.--MIZS 2950 from "Valle de
Santiago" (= lower Rio Zamora), Provincia Morona-Santiago, Ecuador;
Enrico Festa collector]. New synonymy.
_Osteocephalus buckleyi_--Goin, 1961:13.
_Hyla carri_ Cochran and Goin, 1970:211 [Holotype.--FMNH 69702 from
Acevedo, Rio Suaza, Departamento Huila, Colombia; Philip
collector]. New synonymy.
_Hyla cabrerai_ Cochran and Goin, 1970:215 [Holotype.--USNM 152759
from Cano Guacaya, tributary of lower Rio Apoporis, Comisaria
Amazonas, Colombia; Isadore Cabrera collector]. New synonymy.
_Justification of Synonymy._--Boulenger (1882:362) listed 11 specimens
in his description of _Hyla buckleyi_. We have examined all of these and
conclude that one (BMNH 1947.2.13.42) is _O. leprieurii_. Cochran and
Goin (1970:213) restricted the type locality to Canelos, Provincia
Pastaza, Ecuador; we here select BMNH 1947.2.13.44 from that locality as
the lectotype. This specimen is a male having a snout-vent length of
37.9 mm; the diameter of the tympanum is 3.5 mm, 81.4 percent of the
diameter of the eye. The type series, exclusive of BMNH 1947.2.13.42
(=_O. leprieurii_) consists of six males having snout-vent lengths of
37.9-44.6 (mean 40.4) mm, and four females having snout-vent lengths of
50.0-53.9 (mean 51.5) mm. The dorsum in the males bears a mixture of
large and small tubercles, whereas the dorsum in females is nearly
smooth. The skin on the flanks, especially the axilla, is areolate. The
coloration consists of a creamy tan ground color with irregular reddish
brown markings on the back and broad transverse bars on the limbs. The
dorsal markings are narrowly bordered by creamy white; those on the back
consist of an interorbital bar and a pair of longitudinal marks
beginning in the scapular region and usually diverging posteriorly in
the sacral region or converging into a broad median blotch. One specimen
has a middorsal creamy white stripe from the tip of the snout to the
vent. In all of the types large dark brown spots are present on the
flanks and posterior surfaces of the thighs. The ventral surfaces are
pale creamy tan with or without diffuse brown spots on the throat and
chest.
The holotype of _Hyla festae_ is a female having a snout-vent length of
75.0 mm; the diameter of the tympanum is 3.9 mm, 57.4 percent of the
diameter of the eye. The skin is smooth on the dorsum and areolate on
the anterior part of the flanks. The dorsum is pale brown with a large
median longitudinal dark brown blotch on the back and broad transverse
bars, narrowly outlined by cream, on the limbs. Dark brown spots are
present on the flanks; the posterior surfaces of the thighs are dark
brown. The throat and belly are grayish white with irregular dark brown
spots.
The holotype of _Hyla carri_ is a female having a snout-vent length of
66.1 mm; the diameter of the tympanum is 4.7 mm, 81.0 percent of the
diameter of the eye. The skin on the dorsum is smooth with scattered
small tubercles and areolate on the anterior part of the flanks. The
dorsum is tan with irregular dark brown blotches on the back and
transverse bars on the limbs; all dorsal markings are narrowly outlined
by creamy white. Dark brown spots are present on the flanks; the venter
and posterior surfaces of the thighs are tan without dark spots.
The holotype of _Hyla cabrerai_ is a female having a snout-vent length
of 52.7 mm; the diameter of the tympanum is 4.0 mm, 76.9 percent of the
diameter of the eye. The skin on the dorsum is weakly tuberculate and
that on the anterior part of the flanks is areolate. The dorsum is
creamy tan with dark brown markings (interorbital bar, reticulations on
occiput, three longitudinal streaks on back, and broad transverse bars
on limbs). Irregular dark brown spots are present on the flanks. The
venter is pinkish tan with small reddish brown spots on the throat and
darker brown spots on the chest and belly.
In their description of _Hyla cabrerai_, Cochran and Goin (1970:217)
stated: "This species, together with _buckleyi_ and _pearsoni_ certainly
make a closely knit group.... Both _buckleyi_ and _cabrerai_ have long
hind legs, with the extended heel reaching to the tip of the snout,
while in _pearsoni_ the extended heel reaches only to the eye. _H.
buckleyi_ has the belly dusky, while it is heavily spotted in _cabrerai_
and is reticulated in _pearsoni_. _H. cabrerai_ seems to have the
heaviest hands with the most webbing between the fingers; the other two
species have the webbing reduced between the fingers." The description
of _Hyla cabrerai_ was based on three specimens. We have examined the
holotype and one paratype (WCAB 13284 from Territorio do Amapa, Brasil).
Another paratype in the private collection of C. J. Goin from Cano Tui,
between Mitu and Raudal de Yurupari, Comisaria de Vaupes, Colombia, was
not examined.
Cochran and Goin (1970:211) based their description of _Hyla carri_ on
one gravid female and stated: "A large _Hyla_ with the vomerine teeth in
two ^^ shaped patches between the somewhat squarish choanae; reduced
webs between the fingers; and a pattern of dorsal dark blotches bordered
by light margins. The species is not similar to any other species known
in Colombia. It is perhaps most closely related to _Hyla claresignata_
of Brazil, from which it can be differentiated by its more heavily
spotted dorsum, larger tympanum, and lack of dark anal spots."
Except for the inclusion of the name in checklists, _Hyla festae_ has
not been mentioned in the literature since the original description.
The wholesale synonymization of names, which, on the bases of their
published diagnoses, seem to apply to distinctly different species, is
possible with the application of uniform criteria to the types and
series of other specimens. In measurements and proportions the type
specimens of the nominal taxa all fall within the range of variation
exhibited by a series of 18 males and 15 females from Provincia Pastaza,
Ecuador, except the ratio of the diameter of the tympanum to that of the
eye in the female holotype of _Hyla festae_. In that specimen the ratio
is 0.574, whereas the ratio in the 15 females from Provincia Pastaza is
0.587-0.905 (mean 0.736).
Ventral coloration is the most variable character among the types. The
venter in the type of _Hyla festae_ is boldly spotted; it is distinctly
spotted in _cabrerai_, uniform tan in _carri_, and tan, flecked, or
spotted in the type series of _buckleyi_. The ventral coloration in
series of specimens from Amazonian Ecuador encompasses that observed in
all of the types, except that of _festae_, which has more ventral
spotting than any other individual.
The webbing on the hand usually excludes the penultimate phalanges of
the fingers, but in some specimens from Amazonian Ecuador the webbing
encompasses the proximal parts of the penultimate phalanges of the
fingers. In a few of these specimens, the holotype of _festae_, and one
paratype of _cabrerai_ the webbing extends to the middle of the
penultimate phalanges of the third and fourth fingers. In the holotype
of _cabrerai_ the webbing extends to the middle of the penultimate
phalanges of the third and fourth fingers and to the base of the disc of
the second finger.
The types of the nominal taxa and series of specimens from Guyana and
Amazonian Ecuador display noticeable variation in dorsal coloration. The
variety of dorsal patterns of all of the types is included in the
variation displayed by the other specimens. All specimens have some
amount of dark spotting on the flanks; all have vertically barred lips,
on which a pale subocular spot usually is evident. Probably the most
unifying physical characteristic of all of the specimens is the nature
of the skin on the anterior part of the flank. The skin is elevated
amidst an irregular network of depressions. This areolate dermal
condition is present in all specimens and does not occur in other
species of _Osteocephalus_. The degree of tubercularity of the skin on
the dorsum is variable and sexually dimorphic. All males are tubercular,
whereas small females are smooth or have only a few scattered tubercles.
Large females usually have pronounced tubercles on the eyelids and
supratympanic fold.
In their description of _Hyla carri_, Cochran and Goin (1970:211)
misrepresented the nature of the dentigerous processes of the
prevomers, which are angular, not ^-shaped. Their suggestion that the
Colombian _Hyla carri_ is related to _Hyla claresignata_ in southeastern
Brasil is unfounded. The latter species is smaller (40 mm), has a yellow
dorsum and venter, dark brown spots dorsolaterally, oblique dentigerous
processes of the prevomers, small tympanum, and smooth skin dorsally.
The ventral coloration of the type of _Hyla festae_ resembles that of
_Osteocephalus verrucigerus_, but the type differs from _verrucigerus_
by having areolate skin on the flanks and distinct dark markings on the
dorsum. In _verrucigerus_ the skin on the flanks is smooth, and the
dorsum is uniform dark brown, except for a tan snout in females.
Comparisons of the types of the nominal species with series of specimens
from Guyana, Colombia, Ecuador, and Peru suggest strongly that the types
are representative of one taxon, the oldest name for which is _Hyla
buckleyi_ Boulenger, 1882. Consequently, we place _Hyla festae_ Peracca,
1904, _Hyla carri_ Cochran and Goin, 1970, and _Hyla cabrerai_ Cochran
and Goin, 1970, as junior synonyms of _Hyla buckleyi_ Boulenger, 1882.
_Diagnosis._--1) Size moderate, sexual dimorphism extreme; maximum
observed snout-vent length in males 48.1 mm, in females 75.1 mm; 2) skin
on dorsum in males bearing a mixture of large and small non-spinous
tubercles; 3) skin on flanks, especially anteriorly, areolate; 4) web
usually extending only to base of antepenultimate phalange on inner edge
of third finger; 5) dorsum pale tan or green with irregular,
longitudinal, dark brown blotches, usually narrowly outlined with cream;
6) venter cream or tan, suffused with brown or marked with brown spots
in some specimens; 7) lips marked with vertical brown and cream bars; 8)
flanks creamy tan with irregular brown spots and/or diagonal marks; 9)
dermal roofing bones of skull lacking exostosis; 10) dermal sphenethmoid
absent; 11) nasals widely separated medially; 12) anteromedial margin of
frontoparietal at mid-level of orbit; 13) frontoparietal fontanelle
partially exposed; 14) palatine serrate; 15) parasphenoid bearing
odontoids; 16) zygomatic ramus of squamosal extending approximately
one-half of distance to maxillary arch; 17) transverse processes of
third presacral vertebra narrower than sacral diapophyses; transverse
processes of presacral vertebrae 3-8 subequal in width and narrower in
males than in females; 18) intermandibularis and submentalis muscles
independent; 19) supramandibular portion of interhyoideus extensively
developed; associated skin forming broad loose fold.
_Osteocephalus buckleyi_ can be distinguished readily from all other
species in the genus by the presence of areolate skin anteriorly on the
flanks and by the rather boldly contrasting dorsal pattern. Furthermore,
females are distinctive in having tubercles on the eyelids and
supratympanic folds.