Tapanatepec on July 13, and at Hueyapan on July 24, 1956. The frogs
were breeding in open ponds in scrub forest and savanna; none was found
in the rainforest. Males call while floating on the water (Pl. 7, fig.
1); the call is a soft "do-ing, do-ing" with a rising tone on the last
note. Numerous individual egg masses were along the bank of a pond near
Tehuantepec; one large composite egg mass there had a surface area of
about one square meter (Pl. 7, fig. 2). The large series from Union
Hidalgo was obtained by digging specimens out of a dry sandy river bank
in the dry season. Some of the individuals were buried to a depth of 25
centimeters.
In life individuals from the Pacific lowlands were dull brown and gray;
those from Acayucan were dark chocolate brown to black with pink or red
blotches, forearms, and dorsal stripe. Not all specimens from the
Atlantic lowlands are so colored; individuals from Cordoba and
Mirador, Veracruz, are like those from Tehuantepec.
=Leptodactylus labialis= Cope
_Oaxaca_: Agua Caliente; Chivela (2); Matias Romero (12); 33
km. N of Matias Romero (4); Mixtequilla; Santa Efigenia;
Tapanatepec; Tehuantepec (38); Tolosita (2); 33 km. W of
Zanatepec (49). _Veracruz_: Acayucan (3); Ciudad Aleman;
Cuatotolapam (10); Hueyapan; La Oaxaquena (4); 38 km. SE of
Jesus Carranza; 20 km. ENE of Jesus Carranza; Novillero (3);
San Lorenzo (2).
Although _Leptodactylus labialis_ does not appear to be so abundant as
_Leptodactylus melanonotus_, the former was found throughout the
lowlands of the isthmus. In the dry season individuals were found along
streams, and in the rainy season breeding congregations were found in
rain pools, marshes, ponds, and even small puddles. The call is a slow
"wort, wort, wort." Males call beneath the water and from beneath rocks
and from holes in the ground. The average snout-vent length of eight
adult males is 37.2 mm. A completely metamorphosed juvenile obtained at
Hueyapan on July 24, 1956, has a snout-vent length of 11 mm.
=Leptodactylus melanonotus= Hallowell
_Oaxaca_: Agua Caliente (25); Cerro Arenal (2); Cerro
Quiengola (3); Cerro San Pedro (3); Chivela (2); Coyol;
Juchitan; Matias Romero (11); Mixtequilla (2); Papaloapan
(2); Salazar (9); Salina Cruz; 11 km. S of Santiago Chivela;
Tapanatepec (17); Tehuantepec (176); Tolosita; Union
Hidalgo; 27 km. W of Zanatepec (6). _Veracruz_: Acayucan;
Cuatotolapam (9); Cosoleacaque; 20 km. ENE of Jesus Carranza
(2); 20 km. SE of Minatitlan (2); Novillero; San Lorenzo
(6).
This frog is abundant throughout the lowlands of the isthmus, where in
the dry season individuals were found along streams and beneath rocks
at a spring seepage. In the rainy season males were calling from nearly
every bit of standing water. The call is a soft clicking sound
resembling that made by striking two small stones together. The average
snout-vent length of ten adult males is 41.8 mm. There is considerable
variation in the extent of the yellowish brown glandular areas on the
belly. Some have none, whereas others have a broad area on the chest, a
band along the flanks, and a thin band across the lower abdomen.
Individuals collected in the dry season vary in the same fashion as do
those collected in the rainy season, at which time they were breeding.
The glands are equally well-developed in adults of both sexes, and were
present in some juveniles with snout-vent lengths of less than 20 mm.
Apparently the development of the glands is not associated with
maturity, sex, or size.
=Diaglena reticulata= Taylor
_Oaxaca_: Cerro Arenal; Chivela; Salina Cruz (26); San
Antonio (3); Tehuantepec (2); 8.6 km. W of Tehuantepec (11);
Zarzamora.
Breeding congregations of this rare frog were found 8.6 kilometers west
of Tehuantepec on July 5, 1956, and at Salina Cruz on July 6, 1958.
Both choruses took place immediately after torrential rains. In both
instances the frogs were in and about open muddy pools in the scrub
forest (Pl. 5, fig. 2); males called from the bank near the water, and
clasping pairs were found only on land (Pl. 8, figs. 1-2). The call is
a loud, nasal "braaa," two to three seconds in duration. Amplexus is
axillary.
The dorsal ground color is light yellowish green tending towards olive
on the head and fading to yellow on the flanks. The ventral surfaces,
including the vocal sac, are white; the iris is golden and flecked with
black. The present series agrees well with the description of
_reticulata_ (based on two specimens) given by Taylor (1942:60). A
detailed analysis of variation, comparison with related species, and
descriptions of tadpoles are reserved for a future report.
=Hyla baudini= Dumeril and Bibron
_Oaxaca_: Bisilana; Cerro Quiengola (2); Cerro San Pedro;
Coyol; Matias Romero (12); Mixtequilla; Rio Sarabia (7);
Salazar; San Antonio; 11 km. S of Santiago Chivela; Santo
Domingo (3); Tapanatepec (2); Tehuantepec (23); Tolosita.
_Veracruz_: Acayucan; Amatitlan; Ciudad Aleman (3);
Cosamaloapan (2); Cuatotolapam (15); 10 km. SE of Hueyapan;
20 km. S of Jesus Carranza; 38 km. S of Jesus Carranza (2);
20 km. ENE of Jesus Carranza (4); La Oaxaquena (2);
Minatitlan (2); Naranja (3); Novillero (9); Rio de las
Playas (2); San Lorenzo (5); Tapalapan (2).
Commonly found on both sides of the isthmus, this large tree frog
nearly always is associated with trees; it is not found in the
savannas, although it breeds in savannas adjacent to rainforest. It
appears to be somewhat more abundant in scrub forest than in
rainforest. In the daytime individuals were found under the outer
sheaths of banana plants, in the axils of leaves of elephant ears
(_Xanthosoma_), in cavities in trees, and on shaded limbs in the
forest. Recently metamorphosed individuals having snout-vent lengths
slightly more than 20 mm. were found in the latter part of July.
=Hyla ebraccata= Cope
_Oaxaca_: Donaji (17); 43 km. N of Matias Romero (27);
Sarabia (6); Tolosita (3); Ubero (17). _Veracruz_: Aquilera.
This small species was found only in forested areas, where calling
males were on bushes and trees around rain pools. The call is a harsh
squawk repeated at intervals of 15 to 20 seconds, followed by a minute
or more of silence, and then repeated. Clasping pairs were found on
bushes and in the water.
The dorsum bears a dark chocolate brown hour glass-shaped mark, which
in some individuals is broken into a large mark posteriorly and a
smaller triangular one on the head and nape. The dorsal ground color
varies from pale cream or ivory to yellow or tan. The intensity of the
dorsal pigmentation is subject to rather rapid change. The flanks,
hands, and anterior part of the venter are lemon yellow; the feet,
thighs, and posterior part of the venter are golden yellow. The dorsal
surface of the shank is yellow to tan with chocolate brown bars or
spots; the heel is pale yellow. There is a dark brown bar in the loreal
region and a dark brown bar extending posteriorly from the eye to a
point above the insertion of the forelimb. The iris is a copper color.
The toes are completely webbed; the fingers, one-third webbed. There is
a small axillary web that is evident when the forelimbs are at right
angles to the body. Twenty males have an average snout-vent length of
28.1 mm.; three females, 35.3 mm. There are no nuptial tuberosities on
the pollex of breeding males.
This species has been collected at Coyame and Catemaco in Los Tuxtlas
and at various localities in Tabasco; it apparently ranges eastward
from southern Veracruz, Mexico, in humid forests to El Peten,
Guatemala.
=Hyla loquax= Gaige and Stuart
_Oaxaca_: Donaji (7); 43 km. N of Matias Romero (21).
_Veracruz_: 19 km. N of Acayucan (4); Aquilera (3); 8 km. SW
of Coatzacoalcos (36); Cuototolapam (11); Naranja (13); San
Lorenzo (8).
In the isthmus this species is known only from the humid forests of the
Gulf lowlands; it is also known from Boca del Rio, Veracruz, and from
Teapa and Villa Hermosa, Tabasco.
Calling males were found on aquatic plants above the water in deep
ponds in the forest where it was necessary for the collector to wade
waist-deep in water to obtain them. The call is a loud "hah-onk."
Individuals, when active at night, are yellowish tan above with light
olive green spots. The flanks, belly, and vocal sac are yellow, and the
anterior and posterior surfaces of the thighs and webbing of the feet
are bright orange-red or tomato red. Individuals found during the day
are grayish brown with olive markings or reddish brown with black
markings. Sleeping individuals are ivory-gray with faint gray markings.
The iris is a bright copper color. Fifteen adult males have an average
snout-vent length of 41.7 mm.; they have no horny nuptial pads on the
pollex.
The relationships of this species are with _Hyla rickardsi_ Taylor, a
species known only from the foothills of the Sierra Madre Oriental in
the states of Puebla and Veracruz. The distinguishing characteristics
of these species are given in Table 1. Living individuals may be
distinguished immediately by the flash colors on the thighs--red in
_loquax_ and yellow in _rickardsi_. The calls of the two species are
distinctly different; that of _rickardsi_ is a high-pitched, loud
rattle continued for several seconds, notably different from the
goose-like honk of _loquax_.
TABLE 1.--COMPARISON OF CERTAIN CHARACTERS IN HYLA LOQUAX
AND HYLA RICKARDSI
=================================+================+====================
CHARACTER | _loquax_ | _rickardsi_
---------------------------------+----------------+--------------------
Toe webbing | Full | Three-fourths
| |
Finger webbing | Three-fourths | One-half
| |
Average snout-vent length (Male) | 41.7 mm. | 37.4 mm.
| |
Tympanum/eye (Male) | 63.2% | 55.8%
| |
Dorsal leg pattern | Barred | Unmarked
| |
Tarsal fold | Tubercular | Absent
| |
Tarsal stripe | Absent or | Broad, indistinct,
| indistinct | or absent
| |
Dorsolateral stripe | Absent | Present
| |
Light line over anus | Broad | Narrow
| |
Flash colors | Red | Yellow
| |
Iris color | Copper | Bronze
---------------------------------+----------------+--------------------
The three specimens from San Lorenzo, Veracruz (USNM 123513-5), were
identified as _Hyla rickardsi_ by Smith (1947:409). The flash colors
have faded in preservative, and so are of no aid in identifying these
specimens. Two are adult females with snout-vent lengths of 35 and 39
mm. In possessing a relatively large tympanum and barred thighs, and in
lacking a dorsolateral stripe they are typical of _loquax_, but in the
amount of webbing on the hands and feet, broad tarsal stripe, and
narrow anal stripe they are like _rickardsi_. The third specimen, a
juvenile, has a snout-vent length of 25 mm. In coloration it resembles
the adults; it has more distinct bars on the limbs. On the basis of
geography these specimens should be _loquax_, for the closest known
record of _rickardsi_ is more than 200 kilometers to the northwest,
whereas _loquax_ is known from several localities around San Lorenzo.
Shannon and Werler (1955:383) described _Hyla axillamembrana_ from the
lower southern slopes of Los Tuxtlas. The unique type is a small male
(27 mm. snout-vent). I have examined the type and find no great
differences between it and small specimens of _loquax_. It is not
possible to determine the color of the thighs, nor was this information
given in the description. _Hyla axillamembrana_ is here considered to
be a synonym of _Hyla loquax_.
=Hyla microcephala martini= Smith
_Oaxaca_: Donaji (15); 43 km. N of Matias Romero (19); Rio
Sarabia (2); Sarabia (11); Tolosita. _Veracruz_: Acayucan
(17); Alvarado (41); Aquilera (21); 8 km. SW of
Coatzacoalcos (10); Cosoleacaque (26); 10 km. SE of
Hueyapan; Naranja (3); Novillero.
This frog is abundant in the Gulf lowlands of the isthmus, where large
breeding congregations were found in grassy ponds on the savannas and
in openings in the forest. Most frequently males were calling from
grasses and reeds in the ponds; many individuals were perched
precariously on thin blades as high as one meter above the water. The
call is a series of low squeaks.
Individuals found at night were pale yellow above with light brown
lines arranged in an irregular pattern on the back, but often forming a
cross or an X-shaped mark in the scapular region. There is a brown
stripe from the nostril to the eye and thence to the groin. Anteriorly
this stripe is bordered above by a thin white or cream-colored line.
Numerous small brown flecks are scattered on the back and dorsal
surface of the shank. In most specimens there are thin transverse brown
bars on the shank. The thighs and undersides of the limbs are golden
yellow; the belly and vocal sac are lemon yellow. The iris is yellowish
brown. During the day individuals assume a pale reddish tan ground
color with darker brown markings. Twenty-five adult males from Alvarado
have an average snout-vent length of 24.1 mm.
=Hyla picta= Guenther
_Oaxaca_: Donaji (8); Sarabia (11); Tolosita (15); Ubero
(6). _Veracruz_: 19 km. N of Acayucan (4); Alvarado (5);
Aquilera; 8 km. SW of Coatzacoalcos; 10 km. SE of Hueyapan
(7); Lerdo de Tejada; Tula (3).
Widespread in the forests, scrub, and savannas on the Gulf lowlands of
the isthmus, these frogs were found breeding at numerous localities.
Males call from grasses and bushes growing in and about ponds. The
call is a high-pitched insect-like trill. At night these frogs are pale
yellow above; they change to light grayish tan during the day. A dark
stripe extends from the nostril to the eye and thence posteriorly to a
point between the axilla and groin. Above this dark stripe is a broader
white stripe. Scattered on the dorsum are brown flecks or spots; the
shanks are marked with poorly-defined cross-bars. The thighs are deep
yellow below and paler above with scattered dark flecks. The belly is
white, and the vocal sac is yellow. The iris is golden. Twenty males
have an average snout-vent length of 21.5 mm.; three females, 24.0 mm.
=Hyla robertmertensi= Taylor
_Oaxaca_: Tapanatepec (28); 7.5 km. NW of Tapanatepec (38);
7.2 km. WNW of Zanatepec (77).
This species was found in the isthmian region only on the Pacific
lowlands at the southern base of the western part of the Sierra Madre
de Chiapas. On July 13, 1956, many large choruses were discovered. The
calling males were on reeds and thorn scrub in and at the edge of
temporary ponds; the call is a cricket-like "creak-creack," quickly
followed by a series of notes "creak-eek-eek-eek-eek."
At night the dorsal ground color is pale yellow; this changes to
pinkish buff during the day. There is a grayish or brown dark stripe
from the nostril to the eye; the stripe continues to the groin. This
dark stripe is bordered above by a narrow white stripe. The belly is
white, and the vocal sac is yellow. The iris is dull reddish brown.
Twenty-five males have an average snout-vent length of 24.7 mm.
=Hyla staufferi= Cope
_Oaxaca_: Chivela; Huilotepec (5); Juchitan (4); Matias
Romero (4); 25 km. N of Matias Romero; Mixtequilla (4); Rio
Sarabia (11); 11 km. S of Santiago Chivela; Sarabia (3);
Tapanatepec (67); Tehuantepec (66); Tolosita (2); Ubero;
Union Hidalgo; Zanatepec (6). _Veracruz_: Acayucan (7);
Alvarado (3); Amatitlan; Aquilera; Ciudad Aleman (3); 8 km.
SW of Coatzacoalcos (9); Cosamaloapan (4); Cosoleacaque (8);
10 km. SE of Hueyapan; Lerdo de Tejada; Novillero (6); Tula
(2).
This is the only species of small hylid that crosses the isthmus.
Calling males were found in and about ponds on the savannas in southern
Veracruz, in ponds in open forest in northern Oaxaca (not in forest
pools), and in temporary pools in the scrub forest on the Pacific
lowlands. Individuals usually called from bushes and reeds in or at the
edge of ponds. The call is a short "braaa." Dates of breeding choruses
indicate that by the time the other small species of hylids in the Gulf
lowlands reach the peak of their breeding season, that of _H.
staufferi_ is essentially over; no large breeding congregations were
found in July. On July 8, 1956, two metamorphosing young were found
clinging to blades of grass in a pond; they had snout-vent lengths of 8
and 9 mm. and tail stumps less than 3 mm. in length. Others were found
on July 13 and 26. The juveniles are nearly unicolor olive green above
and white below.
In life the adults vary greatly in color pattern. The dorsal ground
color is yellowish tan to olive brown with olive brown or dark brown
spots, some of which in certain individuals are connected to form
longitudinal dark stripes. On the posterior surface of the thighs are
small white flecks. The belly is white, and the vocal sac is a rich
yellow. Twenty males have an average snout-vent length of 26.3 mm.;
they have no horny nuptial pads. No noticeable differences in either
color or body proportions were found between the populations on either
side of the isthmus.
=Hylella sumichrasti= Brocchi
_Oaxaca_: Cerro Arenal (5); Cerro San Pedro (2); Escurano;
La Concepcion (41); Portillo Los Nanches (6); San Antonio
(16); 11 km. S of Santiago Chivela (18); Santa Lucia (7);
Tapanatepec (5); Tehuantepec (8); Tenango (49); Tres Cruces
(19).
With the exception of the series from 11 kilometers south of Santiago
Chivela, most of these specimens were found in small arboreal
bromeliads during the dry season. Males were found along a clear,
shallow, rocky stream south of Santiago Chivela on July 6, 1956. The
frogs were calling from bushes and rocks in and along the stream. When
disturbed, they jumped into the water and floated downstream until they
were able to hold onto a rock or other object. The call is a loud
"bra-a-ah." In breeding individuals the dorsum is pale yellow; the
belly is white, and the vocal sac is yellow. The iris is pale golden
yellow. Eighteen males have an average snout-vent length of 25.2 mm.
All have dark brown nuptial tuberosities on the pollex.
Certain diagnostic characters of this species as given by Taylor
(1943a:50) and Taylor and Smith (1945:598) are in need of revision.
_Hylella sumichrasti_ has been characterized as having no vocal sac,
rarely having vomerine teeth, and as having a relatively smooth throat.
The vocal sac in breeding males is quite evident; it is single, median,
and when expanded, spherical. The openings into the vocal sac are
narrow slits along the inner posterior border of the jaw rami. Of 151
specimens studied, 74 have vomerine ridges between the choanae, and 36
of these have one to three teeth on each ridge. The belly and
undersurfaces of the thighs are granular; the throat is only somewhat
less so. The granular condition may be correlated with breeding, for
specimens obtained from bromeliads in the dry season had rather smooth
throats. It seems that the vocal sac atrophys in the non-breeding
season. These seasonal changes may account for the diagnoses given by
Taylor (_op. cit._) and Taylor and Smith (_op. cit._); likewise, since
many of the specimens obtained by Smith in the dry season were
juveniles and subadults, the development of the vomerine ridges could
not be diagnosed properly.
The range of this species encompasses the Pacific slopes of the Isthmus
of Tehuantepec eastward to the upper Cintalapa Valley and vicinity of
Tonala in western Chiapas. Priscilla Starrett collected tadpoles of _H.
sumichrasti_ from a stream 19 km. N of Arriaga, Chiapas. These limited
observations on the ecology of this frog suggest that it breeds in the
fast-moving streams of the Pacific slopes, and that it seeks shelter in
arboreal bromeliads during the dry season.
=Phrynohyas modesta= Taylor and Smith
_Oaxaca_: Tuxtepec. _Veracruz_: 20 km. S of Jesus Carranza;
20 km. ENE of Jesus Carranza (2); Minatitlan.
I have not collected this species in the isthmus. The locality records
indicate that the range is discontinuous (Duellman, 1956:27). The
species occurs on the humid Pacific slopes from south-central Chiapas
eastward to El Salvador and on the humid Gulf lowlands from southern
Veracruz eastward into Tabasco, but is unknown from the dry Pacific
slopes and plains in the isthmus.
The acquisition of several specimens of this species in southern
Veracruz, Tabasco, and Oaxaca, together with a knowledge of the
variation displayed by _Phrynohyas spilomma_, suggests that _modesta_
may be a color variety of _spilomma_.
=Phrynohyas spilomma= Cope
_Oaxaca_: Tapanatepec (3). _Veracruz_: Amatitlan (12);
Chacaltianguis (2); Ciudad Aleman (6); Cosamaloapan;
Novillero (3).
Like the preceding species, this frog is unknown from the arid Pacific
lowlands of the isthmus; its presence at Tapanatepec, a locality
situated in more mesic conditions than prevail on the Plains of
Tehuantepec, indicates that it may have a distribution on the Pacific
slopes much like that of _P. modesta_. Furthermore, this frog was not
detected in the rainforests of the Gulf lowlands; in that region it was
found only in scrub forest and savanna.
On July 26, 1956, numerous choruses of these frogs were heard between
Ciudad Aleman and Tlacotalpan, Veracruz. The call is a loud, nasal
"grawl" repeated continuously. The males call from the water. Several
clasping pairs were found in shallow grassy ponds amidst the scrub
forest. The ground color varies from reddish brown to tan with dark
brown dorsal markings. The iris is golden, and the vocal sacs are dark
olive brown. After a light shower during the dry season, six
individuals were found on the low branches of trees at night near
Ciudad Aleman.
=Phyllomedusa callidryas taylori= Funkhouser
_Oaxaca_: Donaji (9); Sarabia (8); Tolosita (6); Ubero (27).
_Veracruz_: Alvarado (7); Aquilera; Berta; Coatzacoalcos
(9); 10 km. SE of Hueyapan (5); Naranja (17).
In life this frog presents a striking array of colors. The dorsum
varies from pale green to dark olive green; there may be scattered
whitish or cream-colored spots on the back. On the flanks are bright
yellow to deep cream-colored vertical bars separated by pale blue or
purple interspaces. The thighs and undersurfaces of the hind limbs are
golden orange; the belly is yellow, and the throat is cream-colored.
The iris is crimson; the transparent part of the lower eyelid has
golden reticulations. When the frog is resting, the forefeet are folded
beneath the throat, and the limbs are folded tightly against the body.
In this position and with the eyes closed and head flattened, this
gaudy frog assumes the appearance of a small elliptical green leaf.
Throughout the month of July, 1956, _Phyllomedusa_ was breeding in
ponds in or adjacent to the rainforest in northern Oaxaca and in
southern Veracruz. Only at Alvarado was it found breeding in a grassy
pond. Males and females alike were found on bushes and trees in and
around the ponds. The call is a single "wank." Amplexing males continue
to call, but the call is softer and less nasal in quality. The eggs are
encased in pale green gelatin and attached to leaves on branches
overhanging the water. Three egg clutches contained 38, 41, and 46
eggs.
=Phyllomedusa dacnicolor= Cope
_Oaxaca_: Escurano; Tehuantepec.
Although it is abundant on the Pacific lowlands to the northwest in
Guerrero, Michoacan, and Colima, this species is known only from two
specimens from Tehuantepec. There is no apparent physical barrier to
their distribution in the isthmus; in the Balsas Basin the species
lives in a hotter, more arid environment than that at Tehuantepec.
=Gastrophryne usta= Cope
_Oaxaca_: Santa Efigenia; Tehuantepec (10); 24 km. W of
Tehuantepec; Tolosita (2). _Veracruz_: Ayentes (6); La
Oaxaquena; Novillero (2); San Lorenzo.
Calling males were found in open scrub forest near Tehuantepec and in
savannas near Novillero. The specimens from Tolosita were found under
cover in a clearing in the forest (Fugler and Webb, 1957:106).