In the following pages various aspects of the occurrence, life
histories, ecology, and variation of the species of amphibians and
reptiles known from southern El Peten are discussed. Only _Cochranella
fleischmanni_ reported by Stuart (1937) from Rio Subin at Santa Teresa
was not collected by us and is excluded. Because more worthwhile
information was gathered for some species than others, the length and
completeness of the accounts vary. All specimens listed are in the
Museum of Natural History at the University of Kansas, to which
institution all catalog numbers refer. Preceding the discussion of each
species is an alphabetical list of localities from which specimens were
obtained; numbers after a locality indicate the number of specimens
obtained at each locality.
=Bolitoglossa dofleini= (Werner)
Chinaja, 1.
An adult female having minute ovarian eggs has a snout-vent length of 81
mm., a tail length of 59 mm., 13 costal grooves, two intercostal spaces
between adpressed toes, 38-35 vomerine teeth in irregular rows forming a
broad arch from a point posterolaterad to the internal nares to a point
near the anterior edge of the parasphenoid teeth, and 43-44
maxilliary-premaxillary teeth. In life the dorsum was rusty brown with
irregular black and orange spots and streaks. The flanks were bluish
gray with black in the costal grooves and creamy tan flecks along the
ventral edge of the flank. The belly and underside of the tail were
yellowish tan with dark brown spots laterally. The limbs were orange
proximally and black distally; the pads of the feet were bluish black.
The dorsal and lateral surfaces of the tail were yellowish orange with
black spots. The iris was grayish yellow.
Stuart (1943:17) reported this species from Finca Volcan, Alta Verapaz.
He diagnosed his specimens as having 13 costal grooves and two or three
intercostal spaces between adpressed toes. He stated that the vomerine
teeth were about 12 in number and that in life the dorsum was mottled
gray and black, the sides gray and brown, and the undersurfaces
uniformly dark gray. These specimens differ noticeably from the
individual from Chinaja in the number of vomerine teeth and in
coloration.
In August, 1961, I obtained a specimen of _Bolitoglossa dofleini_ at
Finca Los Alpes, Alta Verapaz, approximately 13 kilometers airline
south-southwest of Finca Volcan and at approximately the same elevation.
Although the salamander was dead when found, it obviously was more
heavily pigmented than the individual from Chinaja. The belly was bluish
gray with black spots laterally; the dorsum was dull brownish gray with
some brownish red streaks. The specimen is a female having small ovarian
eggs, a snout-vent length of 90 mm., 13 costal grooves, and two
intercostal spaces between adpressed limbs. There are 28-29 vomerine
teeth, more than twice as many as in specimens from Finca Volcan
(Stuart, 1943:17), but noticeably fewer than in the specimen from
Chinaja.
The presence of this species at Chinaja lends support to the idea that
the specimen from the Rio de la Pasion listed by Brocchi (1882:116)
also is _Bolitoglossa dofleini_. Furthermore, the confirmed presence of
this species in the lowlands of El Peten suggests that there may be
genetic connection between _B. dofleini_ in the Alta Verapaz and _B.
yucatana_ in the Yucatan Peninsula. _Bolitoglossa yucatana_ differs from
_B. dofleini_ in having five intercostal spaces between adpressed toes
and in having a different color pattern. Both are robust species having
no close relationships to other species of _Bolitoglossa_ in northern
Central America.
The specimen from Chinaja was found in water in the axil of a large
elephant-ear plant (_Xanthosoma_) by day in March. Its stomach contained
fragments of beetles and a large roach. The natives did not know
salamanders and had no name for them.
=Bolitoglossa moreleti mulleri= (Brocchi)
Chinaja, 2; Rio San Roman, 1.
One specimen is a female having a snout-vent length of 80 mm., a tail
length of 82 mm., and a total length of 162 mm. It contains 63 large
eggs, the largest of which has a diameter of about three millimeters.
This specimen has 13 costal grooves, four intercostal spaces between
adpressed toes, and 12-13 vomerine teeth. A juvenile having a snout-vent
length of 39 mm. and a tail length of 33 mm. has 12 costal grooves,
three intercostal spaces between adpressed toes, and 8-8 vomerine teeth.
In life these salamanders were uniformly dull brownish black above with
a dull creamy yellow irregular dorsal stripe beginning on the occiput
and continuing onto the tail. There are no yellow or orange streaks or
flecks on the head or limbs. The specimen from the Rio San Roman was
taken from the stomach of a _Pliocercus euryzonus aequalis_ and has not
been studied in detail, because of its poor condition.
The present specimens show no tendency for the development of a broad
irregular dorsal band that encloses black spots or forms irregular
dorsolateral stripes, as is characteristic of _B. moreleti mexicanus_, a
subspecies that has been reported from La Libertad (Stuart, 1935:35) and
Piedras Negras (Taylor and Smith, 1945:545) in El Peten, and from
Xunantunich, British Honduras (Neill and Allen, 1959:20).
Schmidt (1936:151) and Stuart (1943:13) found _B. moreleti mulleri_ in
bromeliads at Finca Samac, Alta Verapaz. Taylor and Smith's (1945:545)
and Neill and Allen's (1959:20) specimens of _B. moreleti mexicanus_
were obtained from bromeliads, but Neill and Allen (_loc. cit._) stated
that the natives in British Honduras said that they had found
salamanders beneath rubbish on the forest floor. My specimens were
obtained from beneath logs on the forest floor in the rainy season.
Possibly in drier environments the species characteristically inhabits
bromeliads, at least in the dry season.
=Bufo marinus= (Linnaeus)
Chinaja, 3; 10 km. NNW of Chinaja, 1; 11 km. NNW of Chinaja,
1.
During both visits to Chinaja this large toad was breeding in a small
permanent pond in the camp. During the day the toads took refuge in
crevices beneath the buildings or beneath large boulders by the pond. At
dusk from four to ten males congregated at the pond and called. Tadpoles
of this species were in the pond in March and in July. One juvenile was
found beneath a rock in the forest, and another was on the forest floor
by day.
The natives' name for this species and the following one is _sapo_.
=Bufo valliceps valliceps= Wiegmann
Chinaja, 52; Rio San Roman, 8; Sayaxche, 2; Toocog, 1.
This is one of the most abundant, or at least conspicuous, amphibians
inhabiting the forest. Breeding congregations were found on February 24,
March 2, March 11, and June 27. At these times the toads were
congregated at temporary ponds in the forest or along small sluggish
streams. Throughout the duration of both visits to Chinaja individual
males called almost nightly at the permanent pond at the camp.
The variation in snout-vent length of 20 males selected at random is
56.7 to 72.5 mm. (average, 64.8 mm.). Two adult females have snout-vent
lengths of 80.4 and 87.6 mm. In all specimens the parotid glands are
somewhat elongated and not rounded as in _Bufo valliceps wilsoni_ (see
Baylor and Stuart, 1961:199). My observations on the condition of the
cranial crests of the toads in El Peten agree with the findings of
Baylor and Stuart (_op. cit._:198) in that hypertrophied crests are
usual in large females. In the shape of the parotids and nature of the
cranial crests the specimens from El Peten are like those from the
Isthmus of Tehuantepec in Mexico. As I pointed out (1960:53), the
validity of the subspecies _Bufo valliceps macrocristatus_, described
from northern Chiapas by Firschein and Smith (1957:219) and supposedly
characterized by hypertrophied cranial crests, is highly doubtful.
In the toads from El Peten the greatest variation is in coloration. The
dorsal ground-color varies from orange and rusty tan to brown, yellowish
tan, and pale gray. In some individuals the flanks and dorsum are one
continuous color, whereas in others a distinct dorsolateral pale colored
band separates the dorsal color from dark brown flanks. In some
individuals the venter is uniform cream color, in others it bears a few
scattered black spots, and in still others there are many spots, some of
which are fused to form a black blotch on the chest. In breeding males
the vocal sac is orange tan. All specimens have a coppery red iris.
Aside from the breeding congregations, active toads were found on the
forest floor at night; a few were there by day. Some individuals were
beneath logs during the day.
=Eleutherodactylus rostralis= (Werner)
Chinaja, 10.
Because of the multiplicity of names and the variation in coloration,
the small terrestrial _Eleutherodactylus_ in southern Mexico and
northern Central America are in a state of taxonomic confusion. Stuart
(1934:7, 1935:37, and 1958:17) referred specimens from El Peten to
_Eleutherodactylus rhodopis_ (Cope). Stuart (1941b:197) described
_Eleutherodactylus anzuetoi_ from Alta Verapaz and El Quiche, Guatemala,
suggested that the new species was an upland relative of
_Eleutherodactylus rostralis_ (Werner), and used that name for the frogs
that he earlier had referred to _Eleutherodactylus rhodopis_. Dunn and
Emlen (1932:24) placed _E. rostralis_ in the synonymy of _E. gollmeri_
(Peters). Examination of series of these frogs from southern Mexico,
Guatemala, and Costa Rica causes me to think that there are four
species; these can be distinguished as follows:
_E. rhodopis._--No web between toes; one tarsal tubercle;
tibiotarsal articulation reaches to nostril; iris bronze in
life.
_E. anzuetoi._--No web between toes; a row of tarsal
tubercles; tibiotarsal articulation reaches to tip of snout;
color of iris unknown.
_E. rostralis._--A vestige of web between toes; no tarsal
tubercles; tibiotarsal articulation reaches snout or slightly
beyond; iris coppery red in life.
_E. gollmeri._--A vestige of web between toes; no tarsal
tubercles; tibiotarsal articulation reaches well beyond snout;
iris coppery red in life.
The presence of webbing between the toes, the absence of tarsal
tubercles, and the coppery red iris distinguish _E. rostralis_ and _E.
gollmeri_ from the other species. Probably _E. rostralis_ and _E.
gollmeri_ are conspecific, but additional specimens are needed from
Nicaragua and Honduras to prove conspecificity. On the other hand, the
characters of the frogs from Chinaja clearly show that they are related
to _E. gollmeri_ to the south and not to _E. rhodopis_ to the north in
Mexico.
At Chinaja, _Eleutherodactylus rostralis_ was more abundant than the
few specimens indicate, for upon being approached the frogs moved
quickly and erratically, soon disappearing in the leaf litter on the
forest floor. Most of the specimens were seen actively moving on the
forest floor in the daytime; one was found beneath a rock, and one was
on the forest floor at night.
=Eleutherodactylus rugulosus rugulosus= (Cope)
Chinaja, 2; 15 km. NW of Chinaja, 4.
These frogs were found on the forest floor by day. With the exception of
one female having a snout-vent length of 69.5 mm., all are juveniles.
The apparent rarity of this species at Chinaja may be due to the absence
of rocky streams, a favorite habitat of this frog. The local name for
this frog is _sapito_, meaning little toad.
=Leptodactylus labialis= (Cope)
Toocog, 1.
One juvenile having a snout-vent length of 16.4 mm. was found at night
beside a pond in the forest. The scarcity of the species of
_Leptodactylus_ in the southern part of El Peten probably is due to the
lack of permanent marshy ponds.
=Leptodactylus melanonotus= (Hallowell)
Sayaxche, 1.
One individual was found beneath a rock beside a stream in the forest.
The local name is _ranita_, meaning little frog.
=Syrrhophus leprus= Cope
Chinaja, 2; 15 km NW of Chinaja, 1.
An adult female having a snout-vent length of 27.5 mm. was found on the
forest floor by day. Two juveniles having snout-vent lengths of 15.5 and
19.0 mm. were beneath rocks on the forest floor. The specimens are
typical of the species as defined by Duellman (1958:8).
=Hyla ebraccata= Cope
Toocog, 66.
This small tree frog congregated in large numbers at a forest pond at
Toocog. Between June 30 and July 2 we collected specimens and observed
the breeding habits of this and other species at the pond. Calling males
were distributed around the pond, where they called from low herbaceous
vegetation at the edge of the pond or from plants rising above the
water. Calling commenced at dusk and continued at least into the early
hours of the morning. On one occasion a female was observed at a
distance of about 50 centimeters away from a calling male sitting on a
blade of grass. The female climbed another blade of grass until she was
about eight centimeters away from the male, at which time he saw her,
stopped calling, jumped to the blade of grass on which she was sitting
and clasped her. Clasping pairs were observed on blades of grass and
leaves of plants above the water; most pairs were less than 50
centimeters above the surface of the pond.
The eggs are deposited on the dorsal surfaces of leaves above the water.
All eggs are in one plane (a single layer) on the leaf. External
membranes are barely visible, as the eggs consist of a single coherent
mass. Eggs in the yolk plug stage have diameters of 1.2 to 1.4 mm.
Seventeen eggs masses were found; these contained from 24 to 76 (average
44) eggs. The jelly is extremely viscous and tacky to the touch. At time
of hatching the jelly becomes less viscous; the tadpoles wriggle until
they reach the edge of the leaf and drop into the water.
Eleven tadpoles were preserved as they hatched; these have total lengths
of 4.5 to 5.0 (average 4.77) mm. Hatchling tadpoles are active swimmers
and have only a small amount of yolk. The largest tadpoles preserved
have total lengths of 13.0 and 13.5 mm. At this size distinctive
sword-tail and bright coloration have developed.
[Illustration: FIG. 2. Tadpole of _Hyla ebraccata_ (KU 59986) from
Toocog, El Peten, Guatemala. x 6.]
Description of fully developed tadpole (KU 59986): Total length, 13.5
mm.; tail-length, 8.4 mm., 62 per cent of total length. Snout, in dorsal
view, bluntly rounded; in lateral view less bluntly rounded; body
depressed; head flattened; mouth terminal; eye large, its diameter 25
per cent of length of body; nostrils near tip of snout and directed
anteriorly; spiracle sinistral and situated postero-ventrad to eye;
cloaca median. Tail-fin thrice depth of tail-musculature, which extends
beyond posterior end of tail-fin giving sword-tail appearance (Fig. 2).
In life, black stripe on each side of body and on top of head; black
band on anterior part of tail and another on the posterior part; body
and anterior part of tail creamy yellow; dark red band between black
bands on tail. Mouth terminal, small, its width about one-fifth width of
body; fleshy ridge dorsally and ventrally; row of small papillae on
ventral lip; no lateral indentations of lips; upper beak massive,
convex, and finely serrate; lower beak small and mostly concealed behind
upper; no teeth (Fig. 3).
[Illustration: FIG. 3. Mouthparts of larval _Hyla ebraccata_ (KU 59986)
from Toocog, El Peten, Guatemala. x 100.]
=Hyla loquax= Gaige and Stuart
Toocog, 14.
These specimens were found at night when they were calling from low
vegetation in a forest pond. Most of the frogs were several meters away
from the edge of the pond. Although two clasping pairs were found, we
obtained no eggs or tadpoles referable to this species.
=Hyla microcephala martini= Smith
Chinaja, 1; Toocog, 21.
The specimen from Chinaja was calling from a small bush at the edge of a
temporary grassy pond in a clearing in the forest. At Toocog this
species was closely associated with _Hyla ebraccata_; males were calling
from herbaceous vegetation in and around the forest pond. These frogs
were not so abundant in the forest at Toocog as they were around ponds
on the savanna at La Libertad.
=Hyla picta= (Guenther)
Toocog, 8.
This small tree frog was calling from herbs in a pond in the forest on
June 30 and July 2. The voice is weak; probably greater numbers of males
were present than are indicated by the few specimens collected, for the
din from the more vociferous species made it impossible to hear _Hyla
picta_ unless one was calling close by.
=Hyla staufferi= Cope
Chinaja, 1.
This individual was calling from a low bush in the clearing at Chinaja.
None was found in the pond in the forest at Toocog. Stuart (1935:38) and
Duellman (1960:63) noted that _Hyla staufferi_ breeds early in the rainy
season. Nevertheless, I think early breeding habits do not account for
the near absence of this species in our collections from southern El
Peten. In early July, 1960, a few individuals were heard at a pond on
the savanna at La Libertad. In mid-July of the same year they were
calling sporadically from temporary ponds in the lower Motagua Valley.
Possibly the individual collected at Chinaja was accidentally
transported there in cargo from Toocog, from which camp at the edge of
the savanna planes fly to Chinaja weekly. My observations on this
species throughout its range in Mexico and Central America indicate that
it inhabits savannas and semi-arid forests and usually is absent from
heavy rainforest. Stuart (1948:34) obtained this species at Cubilquitz
in the lowlands of Alta Verapaz.
=Phyllomedusa callidryas taylori= Funkhouser
Toocog, 25.
Between June 30 and July 2 this species was abundant at a pond in the
forest at Toocog. Calling males were as high as five meters in bushes
and trees around the pond. At dusk males were observed descending a
vine-covered tree at the edge of the pond; this strongly suggests that
the frogs retreat to this tree and others like it for diurnal seclusion.
Clasping pairs were found on branches and leaves above the water. The
eggs are deposited in clumps usually on vertical leaves, but sometimes
on horizontal leaves or on branches, vines, and aerial roots above the
water. Twenty-six clutches of eggs contained from 14 to 44 (average 29)
eggs. In a clutch in which the eggs are in yolk plug stage the average
diameter of the embryos is 2.3 mm. and that of the vitelline membranes,
3.4 mm. Most of the eggs are in the external part of the gelatinous
mass; the jelly is clear. The yolk is pale green, and the animal pole is
brown. As development ensues, the yolk becomes yellow and the embryo
first dark brown and then pale grayish tan. Upon hatching the tadpoles
wriggle free of the jelly and drop into the water. One clutch of 19 eggs
was observed to hatch in three minutes. Apparently, on dropping into the
water the hatchling tadpoles go to the bottom of the pond, for one or
two minutes pass from the time they enter the water until they reappear
near the surface. The average total length of seven hatchling tadpoles
is 7.4 mm. There is a moderate amount of yolk, but this does not form a
large ventral bulge. Large tadpoles congregate in the sunny parts of the
pond, where they were observed just beneath the surface. Many had their
mouths at the surface. Except for constant fluttering of the tip of the
tail, they lie quietly with the axis of the body at an angle of about 45
degrees with the surface of the water.
Description of tadpole (KU 60006): total length, 24.5 mm.; tail-length,
15.4 mm.; body broader than deep; head moderately flattened; snout
viewed from above blunt; nostrils close to snout and directed dorsally;
eyes of moderate size and directed laterally; mouth directed
anteroventrally; anus median; spiracle ventral, its opening just to left
of midline slightly more than one-half distance from tip of snout to
vent. Tail-fin slightly more than twice as deep as tail musculature,
which curves upward posteriorly; tail-fin narrowly extending to tip of
tail (Fig. 4). Color in life pale gray; in preservative white with
scattered melanophores; tail-fin transparent.
[Illustration: FIG. 4. Tadpole of _Phyllomedusa callidryas taylori_ (KU
60006) from Toocog, El Peten, Guatemala. x 4.]
Upper lip having single row of papillae laterally, but none medially;
lower lip having single row of papillae; no lateral indentation of lips;
two or more rows of papillae at lateral corners of lips; tooth-rows 2/3;
second upper tooth row as long as first, interrupted medially; inner
lower tooth-row as long as upper rows, interrupted medially; second and
third lower rows decreasingly shorter; upper beak moderate in size and
having long lateral projections; lower beak moderate in size; both beaks
finely serrate (Fig. 5).
[Illustration: FIG. 5. Mouthparts of larval _Phyllomedusa callidryas
taylori_ (KU 60006) from Toocog, El Peten, Guatemala. x 30.]
=Smilisca baudini= (Dumeril and Bibron)
Chinaja, 9; 20 km. NNW of Chinaja, 42; Rio de la Pasion, 1;
Rio San Roman, 5; Sayaxche; Toocog, 2.
Individuals of this species were found at night sitting on bushes and
small trees in the forest in February and March and again in June and
July. One was in the axil of a leaf of a _Xanthosoma_. In June and July
males were heard nearly every night. The series of specimens from 20
kilometers north-northwest of Chinaja was taken from a breeding
congregation in a shallow muddy pool in the forest. Tadpoles of this
species were in small, often muddy pools in the forest. To my knowledge
_Smilisca baudini_ is the only hylid to breed in these pools at Chinaja,
although perhaps _Smilisca phaeota_ also utilizes them. The only other
amphibian at Chinaja known to breed in the pools is _Bufo valliceps
valliceps_. Although two specimens were on bushes at night at Toocog,
_Smilisca baudini_ was not present at the pond where five other species
of hylids were breeding. Nevertheless, _Smilisca baudini_ was calling
from two ponds on the savannas near La Libertad. All of the specimens
from southern El Peten have yellow or yellowish white flanks and
ventrolateral surfaces.
=Smilisca phaeota cyanosticta= (Smith)
Chinaja, 4; 10 km. NNW of Chinaja, 1.
All specimens were found in February and March. Those from Chinaja were
obtained from _Xanthosoma_ and bromeliads; the individual from 10
kilometers north-northwest of Chinaja is an adult male that was calling
from a puddle in a fallen tree on March 13. A juvenile having a
snout-vent length of 34.7 mm. lacks the pale blue spots on the thighs;
instead, the anterior and posterior surfaces of the thighs are bright
red.
=Hypopachus cuneus nigroreticulatus= Taylor
Toocog, 1.
An adult male having a snout-vent length of 41.7 mm. was found at night
on the forest floor at the edge of a temporary pond. In life the dorsum
was dark brown with chocolate brown markings; the stripe on the side of
the head was white; the middorsal stripe was pale orange; the belly was
black and white, and the iris was a bronze color.
Characteristically this species inhabits savannas and open forest; thus,
its occurrence in the rainforest at Toocog is surprising. This is the
southernmost record for the species in El Peten; to the south in the
highlands it is replaced by the smaller _Hypopachus inguinalis_, having
rounded, instead of compressed, metatarsal tubercles.
=Rana palmipes= Spix
Chinaja, 11; 15 km. NW of Chinaja, 1; 20 km. NNW of Chinaja,
1.
With the exception of one recently metamorphosed juvenile having a
snout-vent length of 30.7 mm. that was found on the forest floor by day
on June 24, and one that was found beside a pool in a cave, all
individuals were found at temporary woodland pools or along sluggish
streams at night. The largest specimen is a female having a snout-vent
length of 107 mm.
=Rana pipiens= Schreber
Chinaja, 1; 20 km. NNW of Chinaja, 1; Rio San Roman, 1;
Toocog, 1.
All specimens were found near water at night. The largest individual is
a female having a snout-vent length of 112.5 mm.
=Crocodylus moreleti= Dumeril and Dumeril
Chinaja, 1; Rio San Roman, 1.
One specimen was obtained from a quiet pool in the Rio San Roman at
night; another was found in a small sluggish stream at Chinaja. Two
large individuals were seen in tributaries to the Rio San Roman. On the
savannas at Toocog two small individuals were obtained in the dry
season, at which time the crocodiles apparently were migrating to water.
The local name for this species is _lagarto_.
=Chelydra rossignoni= (Bocourt)
Chinaja, 1; 20 km. NNW of Chinaja, 1.
The paucity of specimens of _Chelydra_ from Central America has resulted
in rather inadequate diagnoses of various populations. The present
specimens have carapace lengths of 250 and 238 mm. and plastral lengths
of 185 and 176 mm. The length of carapace/bridge ratio is 6.0 and 6.1
per cent. Each individual has four barbels, the median pair of which are
extremely long. In KU 55977 the lateral pair of barbels is forked at the
base. The relative length of the plastral bridge in these specimens
compares favorable with the ratio (.06-.08) given by Schmidt (1946:4)
for five specimens from Honduras. _Chelydra serpentina_, which may occur
sympatrically with _C. rossignoni_ in some parts of Central America, has
a narrower plastral bridge and only two barbels beneath the chin.
Furthermore, _C. rossignoni_ and _C. osceola_ in Florida have long, flat
tubercles on the dorsal and lateral surfaces of the neck, whereas _C.
serpentina_ has short, round tubercles.
The specimen from Chinaja was found in a small sluggish stream; the
other individual was in a muddy pool in the forest. The local name is
_sambodanga_.
=Claudius angustatus= Cope