The Amphibians and Reptiles of Michoacan, Mexico Part 5

Sci., 39:352, 1937.--1 mile north of Rodriguez Clara, Veracruz, Mexico.

_Microbatrachylus pygmaeus_ Taylor, Univ. Kansas Sci. Bull., 26:500, November 27, 1940.

_Microbatrachylus albolabris_ Taylor, Univ. Kansas Sci.

Bull., 26:502, November 27, 1940.--2 miles west of Cordoba, Veracruz, Mexico.

_Microbatrachylus minimus_ Taylor, Univ. Kansas Sci. Bull., 26:507, November 27, 1940.--Agua del Obispo, Guerrero, Mexico.

_Microbatrachylus imitator_ Taylor, Univ. Kansas Sci. Bull., 28:70, May 15, 1942.--La Esperanza, Chiapas, Mexico.

Arteaga (328).

This large series (UMMZ 119247-8) was collected on June 22 and 23, 1958, before the onset of the heavy summer rains. The frogs were found in a shaded ravine at the north edge of Arteaga; they were obtained during the day, at which time they were actively moving about in the leaf litter along a small stream.

These frogs are all referred to _M. pygmaeus_, because this is the earliest name available for frogs showing the variation in characteristics displayed by this large series. The characters used by Taylor (1936a, 1940d, 1941a, and 1942b) and Smith and Taylor (1948) to distinguish the various species of _Microbatrachylus_ include color pattern, relative length of the hind limb, presence and position of dorsal dermal folds or pustules, relative size of inner and outer metatarsal tubercles, and the number of palmar tubercles. All specimens from Arteaga have two palmar tubercles; the inner and outer metatarsal tubercles are subequal in size. Furthermore, aside from s.e.xual difference, there is little variation in the relative length of the hind limbs (Table 3). However, many color patterns do exist in the series; each of these color patterns is described below.

TABLE 3.--SNOUT-VENT LENGTH EXPRESSED AS A PERCENTAGE OF TIBIA LENGTH IN ANIMALS OF SIX COLOR PATTERNS OF MICROBATRACHYLUS PYGMAEUS. (LETTERS REFER TO THE VARIANTS HAVING THE COLOR PATTERN DISCUSSED IMMEDIATELY BELOW)

+------------+-----------+---------+---------+----+--------+ | | | Number | Range | | Twice | | Color | s.e.x | of | of |Mean|standard| |Pattern | |specimens|variation| | error | | | | | | |of mean | +------------+-----------+---------+---------+----+--------+ | A | Male | 25 |51.4-57.5|55.2| 3.34 | | | Female | 25 |49.3-54.9|51.6| 3.12 | | B | Male | 20 |51.0-57.1|55.4| 2.44 | | | Female | 21 |47.3-54.9|51.2| 3.52 | | C | Male | 6 |54.5-56.2|55.2| .... | | | Female | 6 |50.0-52.9|51.6| .... | | D | Male | 17 |52.9-58.2|55.4| 2.64 | | | Female | 14 |48.5-56.6|52.1| 4.16 | | E | Male | 10 |50.9-56.9|55.1| 3.40 | | | Female | 7 |49.6-54.5|51.6| .... | | F | Female | 2 |51.9-52.6|52.3| .... | +------------+-----------+---------+---------+----+--------+

A.--225 specimens: Dorsum mottled brown and cream, usually with a dark spot between the eyes and one or two dark V-shaped marks with the apex anteriorly on the back; 55 of these have a narrow cream-colored line from the tip of the snout to the vent and thence onto the posterior surfaces of the thighs. All are pustulate above; in most specimens the pustules form no pattern, but in some they tend to form a V in the scapular region.

B.--41 specimens: Dorsum pale tan or cream-color with brown mottling on flanks; a brown interorbital bar and a brown chevron in scapular region.

Dorsum irregularly pustulate; in some specimens the pustules tend to form a V in the scapular region.

C.--12 specimens: Dorsum colored like "A", but having a broad yellow stripe narrowly bordered by black from the tip of the snout to the vent; in some specimens there is a narrow yellow stripe on the posterior surfaces of the thighs. The dorsum is irregularly pustulate.

D.--31 specimens: Dorsum variably streaked with cream-color or pale tan and brown; usually a broad cream-colored stripe from eyelid to groin bordered laterally by a somewhat narrower brown stripe; middorsal area cream-color and separated from dorsolateral cream-colored stripe by a brown stripe, or middorsal area brown with a cream-colored or yellow, narrow stripe from tip of snout to vent; a dark stripe from tympanum to flank; dorsal surfaces of heels creamy white to pale orange; a.n.a.l patch brown. A dermal ridge from posterior edge of eyelid to rump; another ridge extends posteromedially from the eyelid; scattered pustules on the dorsum in some specimens.

E.--17 specimens: A narrow dark stripe from snout, through nostril and eye, over tympanum, to vent, enclosing a unicolor dorsum (reddish tan to yellowish tan in life); heels pale tan or yellow above; a.n.a.l patch black. A faint dermal ridge from posterior edge of eyelid to rump, or part way to rump.

F.--2 specimens: Mottled brown and cream-color above; upper lips and upper arms white. A dermal fold from posterior edge of eyelid to rump; scattered pustules on dorsum.

Some of these color variants are a.s.signable to names proposed by Taylor: "A" and "B" undoubtedly are _M. pygmaeus_ (Taylor, 1936a); "C" probably is _M. pygmaeus_; "D" is referable to _M. minimus_ (Taylor, 1940d) in most characteristics, although the coloration is more nearly like that of _M. lineatissimus_ (Taylor, 1941a), a larger species characterized by a relatively long hind limb; "E" apparently is _M. imitator_ (Taylor, 1942b); "F" is _M. albolabris_ (Taylor, 1940d). Examination of series of these frogs from other parts of Mexico shows a similar composition of color variants. Of 78 specimens from the Rio Sarabia and the village of Sarabia in Oaxaca (UMMZ 115428-37), 57 are "A," six are "D," three are "E," and 12 are "F"; of 22 specimens from Teapa, Tabasco (UMMZ 113829), 11 are "A," five are "D," two are "E," and four are "F"; of 33 specimens from Potrero Viejo, Veracruz (USNM 115447-58, 115461-71, 116840-2, 116864-70), ten are "A," 13 are "E," and ten are "F"; of 31 specimens from La Esperanza, Chiapas (USNM 115477-9, 116827-39, 116849-63), 28 are "A" and four are "F."

It is highly doubtful if these color variants are actually distinct species. Goin (1950 and 1954) in his studies of inheritance of color pattern in West Indian species of the genus _Eleutherodactylus_ has shown that similar color pattern variants come from the same clutch of eggs; furthermore, Goin has worked out the genetic ratios of certain of these variants. Heathwole (_in litt._) obtained "normal" specimens and individuals having a broad middorsal stripe ("C" in figure 9) from a clutch of eggs of _Eleutherodactylus gollmeri_. The presence of a broad middorsal yellow stripe is common in _Eleutherodactylus rugulosus_.

Perhaps the most interesting aspect of variability in color pattern in Mexican eleutherodactylids is the parallelism between members of the _Eleutherodactylus rhodopis_-group and some members of _Microbatrachylus_. In the former group there are white-lipped individuals (_Eleutherodactylus beatae_ Boulenger), individuals having a unicolor reddish or yellowish dorsum (_E. dorsoconcolor_ Taylor), and individuals having a dorsal pattern of irregular longitudinal brown and cream-colored streaks (_E. venustus_ Gunther). In the humid forests of southern Veracruz, northern Oaxaca, and Chiapas members of both groups occur sympatrically. A proper understanding of the evolutionary significance of these variants in the two groups, as well as proper allocation of the presently recognized species, must await experimental evidence based on studies of the inheritance of color pattern.

Nevertheless, at present it is apparent that certain characters, especially the nature of the dermal folds and pustules, and the color pattern, are of little taxonomic value in distinguis.h.i.+ng "species" of _Microbatrachylus_. The data derived from a study of the large series from Arteaga, together with that from the other series examined, suggests that _Microbatrachylus albolabris_, _imitator_, _minimus_, and _pygmaeus_ are morphotypes of one species. Of these names, _pygmaeus_ is the oldest. Consequently _Microbatrachylus pygmaeus_ has been used here for the series from Arteaga.

Although _Microbatrachylus hobartsmithi_, a species distinguished from all of the above by the presence of tubercles on the outer edge of the tarsus, is known from Michoacan northward into Nayarit, _Microbatrachylus pygmaeus_ previously has not been known north of Guerrero, where it occurs in habitats similar to that in which it was collected at Arteaga.

~Eleutherodactylus augusti cactorum~ Taylor

_Eleutherodactylus cactorum_ Taylor, Univ. Kansas Sci. Bull., 25:391, July 10, 1939.--20 miles northwest of Tehuacan, Puebla, Mexico.

_Eleutherodactylus augusti cactorum_, Zweifel, Amer. Mus.

Novitates, 1813:20, December 23, 1956.

Cheran; Coalcoman; Uruapan.

The few specimens indicate that this species occurs at moderate to high elevations in the state. The specimens from Cheran and Uruapan were obtained in pine forests; the specimen from Coalcoman was found on a rocky hillside covered with dense forest and located about 100 meters below the lower limits of the pine forest in the area. A specimen from Rancho Reparto (elevation 1850 meters) on the west slope of Cerro Barolosa was lost.

The specimen from Coalcoman (UMMZ 104728) is a juvenile having a snout-vent length of 25.0 mm. In life it was tan above, mottled with olive-green. The ventral surfaces were gray; the hind limbs were distinctly barred with yellow and brown, and the lips were barred with yellow and black.

~Eleutherodactylus occidentalis~ Taylor

_Eleutherodactylus occidentalis_ Taylor, Proc. Biol. Soc.

Was.h.i.+ngton, 54:91, July 31, 1941.--Hacienda El Florencio, Zacatecas, Mexico.

Arteaga (2); Cascada Tzararacua; Coalcoman (2); 19 km. SW of Coire (3); La Placita (7); Los Reyes; Ostula (4); Pomaro (2).

The locality records for this species suggest that it is a member of a group of animals, the distribution of which includes the western part of the Mexican Plateau and the Pacific lowlands. In Michoacan this frog has been collected in pine-oak forest at Cascada Tzararacua and at Los Reyes, in arid scrub forest at Arteaga and Coalcoman, and in tropical semi-deciduous forest on the lower Pacific slopes of the Sierra de Coalcoman. On July 5, 1950, James Peters (1954:6) found calling males at La Placita.

Most of the specimens are immature; four adult males have snout-vent lengths of 30.9-33.0 (32.2) mm. In all specimens the first finger is noticeably longer than the second; the inner metatarsal tubercle is large, flat, and cream-colored, contrasting with the dark brown sole of the foot. When the hind limbs are adpressed, the heels broadly overlap.

Characteristically, a dark line extends from the snout, through the eye, above the tympanum, to a point above the insertion of the forelimb.

Usually there is a dark bar behind the tympanum, two dark brown bars from the eye to the mouth and thence onto the lower jaw, and another dark bar on the upper lip between the eye and nostril. One adult from Arteaga, an adult and a juvenile from La Placita, and one juvenile each from Coire, Ostula, and Pomaro, have the lower lip barred with dark brown and white, and have a white stripe extending the length of the upper lip. In life the dorsum varies from dark gray or olive-brown to tan or reddish brown.

This species belongs to a group containing two other populations that are currently recognized as species--_calcitrans_, known only from Omiltemi, Guerrero, and _mexica.n.u.s_, reported from the mountains of Oaxaca. Another apparently undescribed member of this group has been collected in the mountains of northern Puebla. The locality records indicate that the group inhabits the mountains on the periphery of the Mexican Plateau, except in western Mexico, where _Eleutherodactylus occidentalis_ extends to the Pacific lowlands.

~Eleutherodactylus rugulosus vocalis~ Taylor

_Eleutherodactylus vocalis_ Taylor, Univ. Kansas Sci. Bull., 26:401, November 27, 1940.--Hacienda El Sabino, Michoacan, Mexico.

Arteaga (10); El Sabino (8); Salitre de Estopilas (3); Tumbiscatio (2); Tzitzio (2).

The distributional data on this frog in Michoacan indicate that it inhabits riparian situations in arroyos and canyons in the lower slopes of the Cordillera Volcanica and the Sierra de Coalcoman, where it has been taken at elevations only below 1100 meters.

The dorsal color of living individuals from Arteaga varied from dark gray and olive brown to tan and reddish brown. The iris was grayish brown. In contrast, individuals from Agua del Obispo, Guerrero, had pale golden eyes; specimens from Matias Romero, Oaxaca, had gold eyes heavily flecked with gray; and individuals from Volcan San Martin, Veracruz, had bronze eyes.

The use of the trinomial here is arbitrary. Frogs of the _Eleutherodactylus rugulosus_ group in Mexico (_rugulosus_, _avocalis_, and _vocalis_) exhibit only slight differences in size, proportions, and coloration (Duellman, 1958c:6). Furthermore, the named populations are allopatric. _Eleutherodactylus rugulosus vocalis_, as defined by Duellman (_loc. cit._), occurs in the foothills of the Sierra Madre Occidental and a.s.sociated ranges from central Sinaloa southward into Michoacan.

~Tomodactylus angustidigitorum~ Taylor

_Tomadactylus angustidigitorum_ Taylor, Univ. Kansas Sci.

Bull., 26:494, November 27, 1940.--Quiroga, Michoacan, Mexico.

Angahuan (6); Apo; Carapan (21); 19 km. S of Carapan (13); Cerro Tancitaro (12); Cheran; Corupu (14); Cuseno Station (14); Opopeo (3); Paracho (11); Paricutin (2); Patzcuaro (3); Quiroga (59); San Juan de Parangaricutiro (16); Tancitaro (25); Uruapan (8); Zacapu (11).

This species is indigenous to the pine-oak forests on the southern rim of the Mexican Plateau, and has been collected at elevations from 1500 to 2500 meters. Males have been observed to call from rocks, rock fences, clumps of gra.s.s, and low bushes; the call is a single "peep." At San Juan de Parangaricutiro numerous specimens were found in the daytime beneath adobe bricks and lava on the volcanic ash derived from Volcan Paricutin; at Paracho individuals were found by day beneath rocks in a pine forest.

In most specimens the dorsum is dark reddish brown, and the prominent inguinal glands are cream-color or pale orange (Pl. 3, Fig. 1). Of eight individuals collected at Paracho, one was reddish brown, two were pinkish tan, three were dark brown, and two were black.