For permission to examine specimens in their care I am indebted to
Charles M. Bogert, American Museum of Natural History (AMNH); Doris M.
Cochran, United States National Museum (USNM); Jean Guibé, Museum
National d'Histoire Naturelle, Paris (MNHN); Robert F. Inger, Chicago
Natural History Museum (CNHM); Hobart M. Smith, University of Illinois
Museum of Natural History (UIMNH); Charles F. Walker, University of
Michigan Museum of Zoology (UMMZ). (Abbreviations of institutions
given above in parentheses are used throughout; the Museum of Natural
History, University of Kansas is abbreviated KU.)

[Pg 472]
For their willing assistance in the field I am grateful to Ann S.
Duellman, Dale L. Hoyt, and John Wellman. Permits for collecting in
México were generously issued by the late Ing. Luis Macías Arellano,
Departamento de la Fauna Silvestre, Dirección General de Caza. The
drawings in figures 1 and 3 were executed by Gail Selfridge. This
research has been supported by the National Science Foundation (NSF
G-9827).

Diagnosis.—Maximum snout-vent length in males 54 mm.; snout in
dorsal profile truncate; tarsal fold strong; inner metatarsal tubercle large,
high, and elongate; outer metatarsal tubercle absent; webbing on foot extending
to middle of antepenultimate phalanx of fourth toe; nuptial spines on thumb small;
thoracic fold absent; anal opening at level of lower edge of femur; dorsum
[Pg 476]
brown or tan; belly cream-color; flanks creamy yellow with brown
reticulations or spots; anal stripe absent; vocal slits present.

Description.—The following description is based on KU 68078 from
Uruapan, Michoacán, México. Adult male having a snout-vent length of
43.2 mm.; tibia length, 22.1 mm., 51.1 per cent of snout-vent length;
foot length (measured from proximal edge of inner metatarsal tubercle
to tip of longest toe), 20.8 mm.; greatest width of head, 15.4 mm.,
35.6 per cent of snout-vent length; head length, 13.9 mm., 32.1 per
cent of snout-vent length; diameter of eye, 5.1 mm.; diameter of
tympanum, 2.4 mm., 47.1 per cent of diameter of eye. Snout in lateral
profile bluntly rounded, in dorsal profile truncate; canthus
pronounced, rounded, not angular; loreal region slightly concave; lips
thick, round, not flaring; nostrils slightly protuberant; internarial
distance, 3.4 mm.; interorbital distance, 4.5 mm., somewhat broader
than width of eyelid, 3.5 mm. A heavy dermal fold from posterior
corner of eye above tympanum and curved downward to insertion of
forearm; tympanum round, its diameter slightly more than its distance
from eye. Forearm not robust; row of small pustules on ventral surface
of forearm; fold on wrist; prepollex moderately enlarged, covered with
small, horny, nuptial spines continuous on edge of digit; row of
spines on inner surface of second finger; subarticular tubercles
large, round, none bifid; supernumerary tubercles rather large, round;
palmar tubercles rather small, flat, elliptical; fingers long,
moderately slender; length of fingers from shortest to longest,
1-2-4-3; discs moderately large, that on third finger slightly larger
than tympanum; rudimentary web between first and second and between
second and third fingers; web between third and fourth fingers
extending about one-fourth length of fourth finger. Heels overlap by
about one-third length of shank when hind limbs adpressed; tibiotarsal
articulation extends to anterior edge of eye; tarsal fold strong,
extending to heel; inner metatarsal tubercle large, high, and
elongate; outer metatarsal tubercle absent; subarticular tubercles
moderately large, round; supernumerary tubercles small, in single rows
on proximal segments of digits; toes moderately short; length of toes
from shortest to longest, 1-2-3-5-4, third and fifth toes about equal
in length; toes about two-thirds webbed; web extending to middle of
antepenultimate phalanx of fourth toe, to discs of first, second, and
fifth toes, and to base of penultimate phalanx of third toe; discs
rather small, about two-thirds size of those on fingers. Anal opening
at level of lower edge of thighs; anal sheath elongate, deeply creased
medially; transverse dermal fold above anus. Skin of dorsal surfaces
of head, body, and limbs faintly areolate; skin of chin, belly, and
ventral surfaces of thighs granular, that of ventral surfaces of
limbs, except thighs, areolate; thoracic fold absent. Tongue nearly
round, slightly longer than wide, shallowly notched behind and barely
free posteriorly. Vomerine teeth 4-4, situated on rounded vomerine
ridges between rather small ovoid inner nares; vocal slits present,
situated along posterior edge of each ramus.

Color (in alcohol) pale brown on dorsal surfaces of head, body, and
limbs; flanks and anterior surfaces of thighs creamy white with dark
brown reticulations; posterior surfaces of thighs tan with creamy
white spots; belly cream-color; anal stripe absent.

Color (in life) pale tan on dorsal surfaces; flanks and anterior
surfaces of thighs pale creamy yellow with purplish brown
reticulations; posterior surfaces of thighs tan with yellow spots;
ventral surfaces yellow; iris pale copper-color.

Variation.—There is little variation in structure. The total number
of vomerine teeth varies from 6 to 14. In some individuals the
supratympanic fold covers the upper part of the tympanum, but at least
the lower part of the tympanum is always visible. The extent of the
webbing between the toes varies from three-fourths to two-thirds
complete. Usually the web extends to some point on the antepenultimate
phalanx of the fourth toe, but in some specimens the web extends to
the base of the penultimate phalanx.

In the large series of specimens from Uruapan, Michoacán, the
coloration of the flanks and anterior surfaces of the thighs varies
from nearly uniform creamy yellow with only fine dark reticulations to
bold reticulations enclosing yellow spots. Some specimens from Oaxaca
and Veracruz have slightly different markings on the flanks; in these
the dark pigment is in the form of irregular spots or dashes, instead
of reticulations.

There is considerable variation in color in the living frogs. The
dorsum varies from greenish tan and pale yellowish tan to reddish
brown, and some individuals are dark chocolate brown.

Distribution.—Hyla bistincta occurs at elevations from 1400 to
2600 meters in the mountains of the Sierra Madre Occidental in western
Jalisco southward through the Cordillera Volcánica in Michoacán,
México, and Morelos, the Sierra de Coalcomán in Michoacán, and the
Sierra Madre del Sur in Guerrero and Oaxaca, and thence northward in
the Sierra Madre Oriental to central Veracruz (Fig. 2).

Specimens examined.—Guerrero: Omiltemi, UIMNH 38023-5. Jalisco: 25
km. SE Autlán, UMMZ 102076. Mexico: 19 km. W Villa Victoria, UIMNH
28162, USNM 114513. Morelos: Cuernavaca, USNM 121523; 3 km. N
Cuernavaca, UIMNH 28168-70. Michoacan: Cerro San Andrés, UMMZ 102075;
Dos Aguas, UMMZ 119193; 12.5 km. ENE Dos Aguas, UMMZ 119194; Los
Conejos, UMMZ 94238-40; Uruapan, KU 68077-8, 69093 (skeleton), UIMNH
20457, 28167, UMMZ 85452-3, 112838, 112839 (16), 115231 (tadpoles),
115232, 115233 (12), 121515, S-1699 (skeleton), S-1826 (skeleton),
USNM 114514-5, 114517-24. Oaxaca: Cerro San Felipe, UIMNH 28163; Pluma
Hidalgo, AMNH 13447; San Lucas Camotlán, USNM 123689; San Vincente,
UIMNH 51346 (Smith and Williams, 1963:23). Veracruz: no specific
locality, USNM 32261; Cumbres de Acultzingo, CNHM 105482-3, UIMNH
28164-6, 49133-4, USNM 114525.

Holotype.—University of Kansas Museum of Natural History No. 58414
from the Río Totolapa, 14.4 kilometers by road west of Huachinango,
Puebla, México, 2280 meters; obtained by John Wellman on June 8, 1960.

Paratypes.—KU 58415-58423, same data as holotype, and UIMNH 50966,
obtained at the type locality by William E. Duellman on February 11,
1961.

Diagnosis.—Maximum snout-vent length in males, 45 mm.; snout in
dorsal profile truncate; tarsal fold short and weak; inner metatarsal
tubercle moderately large, elliptical, and flat; outer metatarsal
tubercle minute, round, and indistinct; webbing extending to base of
terminal phalanx of fourth toe; nuptial [Pg 479]spines on thumb absent;
thoracic fold absent; anal opening at level of middle of thigh; dorsum
olive-green with black reticulations; venter cream color with brown
flecks on chin; flanks pale grayish green with brown spots; anal
stripe absent; row of white flecks above and a row below anus; vocal
slits absent.

Description of Holotype.—Adult male having a snout-vent lenth of
44.4 mm.; tibia length, 22.2 mm., 50 per cent of snout-vent length;
foot length (measured from proximal edge of inner metatarsal tubercle
to tip of longest toe), 20.4 mm.; greatest width of head, 14.0 mm.,
31.5 per cent of snout-vent length; head length, 13.6 mm., 30.6 per
cent of snout-vent length; diameter of eye, 5.0 mm.; diameter of
tympanum, 1.6 mm., 32.0 per cent of diameter of eye. Snout in lateral
profile bluntly rounded, in dorsal profile truncate (Fig. 3); canthus
pronounced, rounded, not angular; loreal region slightly concave; lips
thick, rounded, not flaring; nostrils slightly protuberant;
internarial distance, 3.7 mm.; interorbital distance, 4.1 mm.,
somewhat broader than width of eyelid, 3.3 mm. A heavy dermal fold
from posterior corner of eye above tympanum and then to insertion of
forearm; tympanum round, its diameter three-fourths its distance from
eye. Forearm rather slender; a short axillary membrane; no fold on
wrist; no nuptial excrescence or spines on enlarged prepollex;
subarticular tubercles moderately small, round; none bifid; few
supernumerary tubercles on proximal segments of digits; large, flat
palmar tubercle present; fingers long and slender; length of fingers
from shortest to longest, 1-2-4-3; discs moderately large, that on
third finger about equal to diameter of tympanum; rudimentary web
between first and second fingers; web between third and fourth fingers
extending to about one-fifth length of fourth finger (Fig. 1). Heels
overlap by about one-third length of tibia when hind limbs adpressed;
tibiotarsal articulation extends to middle of eye; tarsal fold weak,
extending from moderately large, flat, elliptical inner metatarsal
tubercle to middle of tarsus; outer metatarsal tubercle minute, round,
indistinct; subarticular tubercles round; single row of small, round
supernumerary tubercles on proximal segments of each digit; toes
moderately short and slender; length of toes from shortest to longest,
1-2-3-5-4, third and fifth about equal in length; toes about
three-fourths webbed; web extending to base of terminal phalanx of
fourth toe; discs small, about two-thirds size of those on fingers.
Anal opening directed posteroventrally at middle of thighs; two
transverse dermal folds above anus; short, thin anal sheath present;
many small tubercles lateral and ventral to anal opening. Skin of
dorsum, chin, and ventral surfaces of limbs smooth; belly moderately
granular; posterior surfaces of thighs heavily granular; no thoracic
fold. Tongue nearly round, shallowly notched behind, free posteriorly
for about one-fourth its length; vomerine teeth, 3-4, long, situated
on posteroventral edges of narrow transverse vomerine ridges between
moderately large, round inner nares; no vocal slits.

Color (in alcohol) purplish brown on dorsal surfaces of head, body,
and limbs; fine darker reticulations on dorsum; flanks pale tan with
dark brown spots; posterior surfaces of thighs tan; chin creamy white
with brown spots; belly dusty white; undersides of thighs and shanks
yellow; webbing grayish brown; undersides of first two fingers dusty
white, of third and fourth fingers and of feet brown; anal stripe
absent; small white flecks above and below anal opening.

Color (in life) dark green on dorsal surfaces of head, body, and limbs;
darker green reticulations on back; flanks dusty white with dark olive-gray
[Pg 480]
mottling; dark olive-gray stripe from nostril through
eye and then to insertion of forelimb; upper lips pale green; inguinal
region, anterior and posterior surfaces of thighs dark yellowish
orange; ventral surfaces of tarsi and shanks, and webbing of feet
dusty yellow; belly white; iris silvery gold.

Variation.—Adult males have snout-vent lengths from 35.3 to 44.4
mm., and adult females from 43.4 to 50.9 mm. No notable variation in
structure is displayed in the type series. In some individuals the
dark reticulation on the dorsum is faint. Juveniles in life had dorsal
colorations varying from rich brown with darker reticulations to pale
green or gray with dark green reticula[Pg 481]tions. Some adults when
collected were pale green with faint or no dorsal reticulations; later
these individuals darkened. In all specimens the anal stripe is
absent, and the flanks are heavily spotted.

Comparisons.—Hyla charadricola differs from all other members of
the Hyla bistincta group in the following combination of characters:
truncate snout, green dorsum, and absence of a thoracic fold. From
other hylids that occur in the same area, Hyla charadricola differs
from Hyla miotympanum and H. arborescandens, both of which are
green dorsally, by having a truncate snout and longer fingers with
less webbing. Hyla eximia, though green, has brown dorsal spots,
shorter fingers, and a round snout. Hyla robertsorum differs in
having a round snout and brown dorsum, and Hyla taeniopus is much
larger, has transverse bands on the limbs, and has extensive webbing
between fingers.

Distribution.—Hyla charadricola inhabits streams in pine and
pine-oak forests at elevations of 2000 to 2300 meters in northern
Puebla and eastern Hidalgo (Fig. 2).

Specimens examined.—Hidalgo: Lago de Tejocotal, 11 km. E
Acaxochitlán, KU 58438, UMMZ 104032, 118165; 4 km. SW Tianguistengo,
KU 53811-2. Puebla: 11.7 km. W Huachinango, UMMZ 121567 (5); Río
Totolapa, 14.4 km. W Huachinango, KU 53813-5, 55624, 58414-37, 59813
(skeleton), 59886 (skeleton), MCZ 34964-5, UIMNH 50966, UMMZ 118166
(5), S-2242 (skeleton).

Diagnosis.—Maximum snout-vent length in males, 48 mm.; snout in
dorsal profile rounded; tarsal fold short and weak; inner metatarsal
tubercle moderate in size and elliptical; outer metatarsal tubercle
small, round, and indistinct; webbing extending to base of penultimate
phalanx of fourth toe; nuptial spines on thumb small; weak thoracic
fold present; anal opening above level of middle of thighs; dorsum
dark brown with dark reticulations; venter brown with cream-colored
flecks; flanks brown with creamy white spots; anal stripe absent;
small white spots in anal region; vocal slits absent.

Description.—The following description is based on KU 57651 from El
Chico Parque Nacional, Hidalgo. Adult male having a snout-vent length
of 45.1 mm.; tibia length, 22.1 mm., 49.0 per cent of snout-vent
length; foot length (measured from proximal edge of inner metatarsal
tubercle to tip of longest toe), 21.5 mm.; greatest width of head,
13.7 mm., 30.4 per cent of snout-vent length; head length, 12.6 mm.,
27.9 per cent of snout-vent length; diameter of eye, 4.0 mm.; diameter
of tympanum, 1.8 mm., 45 per cent of diameter of eye. Snout short, in
lateral profile blunt, in dorsal profile round; canthus rounded;
loreal region slightly concave; lips thick, round, and not flaring;
nostrils slightly protuberant; internarial distance, 3.6 mm.;
interorbital distance, 4.0 mm., slightly broader than width of eyelid,
3.5 mm. A moderately heavy dermal fold from posterior corner of eye
above tympanum and curving downward towards insertion of forearm;
tympanum nearly round, covered by dermal fold above, its diameter
slightly less than its distance from eye. Forearm moderately robust;
distinct fold on wrist; prepollex much enlarged with patch of small
nuptial spines continuous on side of digit; similar line of nuptial
spines on inner edge of second finger; subarticular tubercles round,
moderate in size, none bifid; supernumerary tubercles small and
present only proximally; fingers long and slender; length of fingers
from shortest to longest, 1-2-4-3; discs moderately large, that on
third finger about size of tympanum; no web between first and second
fingers; rudimentary web between other fingers. Legs robust; heels
over-lap by about one-fourth length of shank when hind limbs
adpressed; tibiotarsal articulation extending to posterior corner of
eye; tarsal fold weak, extending to about middle of tarsus; inner
metatarsal tubercle moderately large, flat, and elliptical; outer
metatarsal tubercle small, round, and indistinct; subarticular
tubercles round; supernumerary tubercles small, in single row on
proximal segments of each digit; toes moderately long and slender;
length of toes from shortest to longest, 1-2-5-3-4, the fifth nearly
as long as third; toes nearly fully webbed; web extending to base of
penultimate phalanx of fourth toe and to discs on other toes; discs
small, about two-thirds size of those on fingers. Anal opening above
middle of thighs; anal sheath short, deeply creased medially; heavy
transverse dermal fold above anus; no large anal tubercles. Skin of
all dorsal surfaces, chin, and ventral surfaces of limbs, except
proximal parts of thighs, smooth; belly and proximal parts of thighs
areolate; thoracic fold present, weak. Tongue elliptical, slightly
longer than wide, not notched behind, and free posteriorly for about
one-fourth of its length; vomerine teeth 3-3, situated on small,
widely separated, transverse ridges between rather small elliptical
inner nares; no vocal slits.

Color (in alcohol) dark brown with irregular darker reticulations on
dorsal surfaces of head, body, and limbs; flanks brown with small
creamy white spots; posterior surfaces of thighs dark brown; chin
creamy tan; belly grayish brown [Pg 483]with cream-colored flecks; ventral
surfaces of limbs pale brown; webbing on feet gray; small white spots
in anal region.

Color (in life) chocolate brown with darker brown reticulations and
irregular blotches above; flanks brown with yellow spots; belly gray
to grayish brown with faint cream-colored spots; iris a deep bronze
color.

Variation.—In males the total number of vomerine teeth varies from
4 to 7. In many specimens the vomerine ridges are larger and more
closely approximated medially than in the specimen described above.
Females attain snout-vent lengths of 51 mm., have as many as 9
vomerine teeth, and have a proportionately larger tympanum than males.
Some of the largest specimens of both sexes have indistinct
cream-colored pustules scattered on the ventral surface of the
forearm. Some individuals have nearly uniform grayish brown ventral
surfaces; in others the chin, as well as the abdomen, is brown with
cream-colored spots. The dorsal surfaces of some specimens are nearly
uniform dark brown with no reticulations. In others the dorsum is
paler brown with distinct darker mottling; in some of these there is
little mottling laterally, so that there is the effect of an
irregular, pale brown, dorsolateral stripe.

Tadpoles.—The tadpoles of this species were described by Rabb and
Mosimann (1955). Tadpoles obtained from streams at 3.3 kilometers
north and at 8.5 kilometers southeast of Zacualtipán, Hidalgo, are
like those described by Rabb and Mosimann in having ⅔ tooth rows,
peglike serrations on the beaks, and long rounded tails. The largest
tadpole (KU 60078) has small hind legs, a body length of 22 mm., and a
total length of 61 mm.

Distribution.—Hyla robertsorum inhabits streams in the pine and fir
forests in the higher parts (2250 to 3050 meters) of the Sierra Madre
Oriental in extreme northern Puebla and eastern Hidalgo (Fig. 4).

Specimens examined.—Hidalgo: 16 km. W Agua Blanca, UMMZ 106432 (6);
El Chico Parque Nacional, CNHM 75786, 100124, KU 57650-71, 59824-5
(skeletons), 59914-5 (skeletons), 71269-95, 71757 (skeleton), UIMNH
10349-64, 27022-35, 39434-49, UMMZ 92462, 106401 (5), 106443
(tadpoles), USNM 114762-85, 134268; 3.3 km. N Zacualtipán, KU 53810,
60078 (tadpoles); 8.5 km. SE Zacualtipán, KU 60079 (tadpoles). Puebla:
Honey, UMMZ 95245.

Diagnosis.—Maximum snout-vent length in males 40 mm.; snout in
dorsal profile round; tarsal fold strong; inner metatarsal tubercle
round and moderate in size; outer metatarsal tubercle small and
indistinct; webbing on foot extending to middle of penultimate phalanx
of fourth toe; nuptial spines on thumb large; thoracic fold present;
anal opening at level of middle of thighs; dorsum dull grayish brown
with scattered indistinct dark flecks; venter cream-color mottled with
brown on throat and chest; flanks grayish brown with cream-colored
reticulations; anal stripe distinct, creamy white, sometimes extending
outward on thighs; white spots or line below anus; vocal slits absent.

Description.—The following description is based on USNM 115028 from
Pan de Olla, Veracruz. Adult male having a snout-vent length of 39.9
mm.; tibia length, 21.0 mm., 52.6 per cent of snout-vent length; foot
length (measured from proximal edge of inner metatarsal tubercle to
tip of longest toe), 20.5 mm.; greatest width of head, 12.8 mm., 32.1
per cent of snout-vent length; head length, 12.3 mm., 30.8 per cent of
snout-vent length. Snout short, in lateral profile bluntly rounded, in
dorsal profile rounded; canthus rounded; loreal region slightly
concave; lips thick, round, and not flaring; nostrils slightly
protuberant; internarial distance, 2.7 mm.; interorbital distance, 3.7
mm., somewhat broader than eyelid, 2.9 mm. A heavy dermal fold from
posterior corner of eye above tympanic region and then to insertion of
forearm; tympanum completely concealed. Forearm moderately robust;
distinct fold on wrist; prepollex enlarged bearing cluster of
moderate-sized, horny, nuptial spines continuous on edge of digit; row
of spines present on second finger; subarticular tubercles round,
small proximally and slightly larger distally; supernumerary tubercles
small and indistinct; three palmar tubercles, median and outer partly
fused; fingers long, moderately slender; discs moderately large;
length of fingers from shortest to longest, 1-2-4-3; second and fourth
fingers subequal in length; webbing between fingers rudimentary. Heels
overlap by about one-fourth length of shank when hind limbs adpressed;
tibiotarsal articulation extends to anterior edge of eye; tarsal fold
thick, low, extending nearly to heel; inner metatarsal tubercle
moderately large and round; outer metatarsal tubercle small and
indistinct; subarticular tubercles small and round; [Pg 486]
supernumerary tubercles small, present on proximal segments of digits; toes
moderately long and slender; length of toes from shortest to longest,
1-2-3-5-4; third and fifth toes subequal in length; toes about
three-fourths webbed; web extending to middle of penultimate phalanx
of fourth toe; discs rather small, about two-thirds size of those on
fingers. Anal opening directed posteroventrally at level of middle of
thighs; anal flap slightly elongate; thick, transverse dermal fold
above anus. Skin of dorsum and ventral surfaces of limbs, except
thighs, smooth; skin of chin, belly, and ventral surfaces of thighs
granular; thoracic fold present. Tongue nearly round, slightly notched
behind, and barely free posteriorly; vomerine teeth 3-3, situated on
posteroventral edges of small, transverse vomerine ridges between
rather large triangular inner nares; no vocal slits.

Color (in alcohol) of dorsal surfaces of head, body, and limbs dull
grayish brown with indistinct scattered darker flecks; flanks grayish
brown with cream-colored reticulations; posterior surfaces of thighs
tan; chin cream-color, mottled with brown; belly creamy yellow; anal
stripe cream-color.

Variation.—In addition to the specimen described above three others
are known. One is a juvenile having a snout-vent length of 29.5 mm.,
and two are females having snout-vent lengths of 46.9 and 41.6 mm.
Variation in structure and coloration between the four specimens is
slight. In the females the tympani are partly visible and are about
one-third the diameter of the eye; the chest is mottled with brown;
the anal stripe extends laterally in the form of a row of
cream-colored dashes and spots onto the posterodorsal surfaces of the
thighs.

Distribution.—This species is known only from a stream at an
elevation of about 1600 meters on the Atlantic slopes of the Sierra
Madre Oriental in central Veracruz (Fig. 4).

Specimens examined.—Veracruz: Pan de Olla, south of Tezuitlán,
Puebla, USNM 115026-9.

Diagnosis.—Maximum snout-vent length in males 54 mm.; snout in
dorsal profile round; tarsal fold strong; inner metatarsal tubercle
small and elliptical; outer metatarsal tubercle small, flat, and
indistinct; foot fully webbed; nuptial spines on thumb small; thoracic
fold absent; anal opening at level of middle of femur; dorsum dull
olive-green; belly creamy yellow; chin gray with yellow flecks; flanks
dull olive-green with scattered cream-colored spots; and stripe faint,
cream-color; vocal slits absent.

Description.—The following description is based on UIMNH 25050 from
Cerro San Felipe, Oaxaca. Adult male having a snout-vent length of
53.7 mm.; tibia length, 26.9 mm., 50.1 per cent of snout-vent length;
foot length (measured from proximal edge of inner metatarsal tubercle
to tip of longest toe), 25.4 mm.; greatest width of head, 17.6 mm.,
32.8 per cent of snout-vent length; head length, 16.0 mm., 29.8 per
cent of snout-vent length; diameter of eye, 5.4 mm.; diameter of
tympanum, 1.5 mm., 27.8 per cent of diameter of eye. Snout short, in
lateral profile bluntly rounded, in dorsal profile broadly round;
canthus absent; loreal region nearly flat; lips thick and not flaring;
nostrils barely protuberant; internarial distance, 3.8 mm.;
interorbital distance, 4.7 mm., somewhat broader than width of eyelid,
3.8 mm. Heavy dermal fold from posterior corner of eye above tympanum
and then to insertion of forearm; tympanum concealed above, its
diameter about equal to its distance from eye. Forearm thick; distinct
fold on wrist; prepollex enlarged bearing patch of small nuptial
spines continuous on side of digit; similar patch on second finger;
subarticular tubercles small and round, none bifid; few supernumerary
tubercles on proximal segments of digits; large, flat palmar tubercle;
fingers long and slender; length of fingers from shortest to longest,
1-2-4-3; discs moderately large; rudimentary web between second and
third fingers and between third and fourth. Legs thick; heels overlap
by about one-fourth length of shank when hindlimbs adpressed;
tibiotarsal articulation extends to posterior corner of eye; tarsal
fold thick, extending to heel; inner metatarsal tubercle small and
elliptical; outer metatarsal tubercle small, flat, and indistinct;
subarticular tubercles small and round; single row of supernumerary
tubercles on proximal segments of each digit; toes moderately short
and slender; length of toes from shortest to longest, 1-2-3-5-4; toes
fully webbed; flap of skin on inner surface of first toe; discs about
same size as those on fingers. Anal opening directed posteroventrally
at middle of thighs; anal sheath moderately elongate; small tubercles
below anal opening. Skin of dorsum rather smooth, somewhat
[Pg 488]
granular on dorsal surfaces of limbs; skin of chin and belly moderately
granular; that of posterior surfaces of thighs smooth; no thoracic
fold. Tongue nearly round, shallowly notched posteriorly, and free for
about one-fourth its length; vomerine teeth 5-5, situated on rounded
ridges between small inner nares; no vocal slits.

Color (in alcohol) dull olive-green on dorsal surfaces of head, body,
and limbs; flanks dull olive-green with scattered cream-colored spots;
posterior surfaces of thighs grayish brown with faint creamy mottling;
chin gray with cream-colored spots; belly creamy yellow, suffused with
gray posteriorly; undersides of feet and webbing gray; anal stripe
faint, pale cream-color.

Variation.—The only other known specimen (MNHN 6331) is a female
having a snout-vent length of 53.7 mm. and resembling the specimen
described above in most details of morphology. In MNHN 6331 the
tympanum is completely concealed, and the 8-7 vomerine teeth are
arranged in two irregular rows. The female has more cream-colored
mottling on the flanks and posterior surfaces of the thighs and more
distinct mottling on the throat than the male described above.

Distribution.—This species is definitely known only from a small stream at
an elevation of 2300 meters in the mountains of central Oaxaca (Fig. 4).

Specimens examined.—Oaxaca: Cerro San Felipe, UIMNH 25050. "Mexico,"
MNHN 6331.