The Amphibians and Reptiles of Michoacan, Mexico Part 2

_Ambystoma tigrinum velasci_, Dunn, Copeia, no. 3:157, November 14, 1940.

Patzcuaro (5); Tacicuaro (9).

Definite specific a.s.signment of these specimens, all larvae, cannot be made at this time. They have shovel-shaped heads and laterally compressed bodies with the dorsal tail-fin extending anteriorly to the back of the head. The eyes are small. The body is pale tan with dark mottling on the tail and flanks. The average snout-vent length for nine specimens from Tacicuaro is 61.0 mm.

The larvae from Tacicuaro (UMMZ 89255) were collected by Dyfrig Forbes in October, 1939; those from Patzcuaro, presumably Lago de Patzcuaro (BMNH 1914.1.28-247-8 and CNHM 948), were collected by Hans Gadow and Seth Meek in 1908.

~Pseudoeurycea belli~ (Gray)

_Spelerpes belli_ Gray, Catalogue Batrachia Gradientia British Museum, p. 46, 1850.--Mexico. Type locality restricted to 2 miles east of Rio Frio, Puebla, Mexico, by Smith and Taylor (1950a:341).

_Pseudoeurycea bellii_, Taylor, Univ. Kansas Sci. Bull., 30:209, June 12, 1944.

Axolotl (2); Carapan; Cerro Tancitaro (84); Macho de Agua; 22 km. W of Mil c.u.mbres; Opopeo; Patzcuaro (8); Puerto Hondo (2): San Jose de la c.u.mbre; San Juan de Parangaricutiro (42); Uruapan (5); Zacapu (4).

This salamander seems to reach its greatest abundance in Michoacan in the Sierra de los Tarascos between Patzcuaro and Tancitaro, where it is found at elevations from 1500 to 2900 meters. It is found less commonly in the eastern part of the Cordillera Volcanica in Michoacan, where it sometimes occurs in a.s.sociation with _Pseudoeurycea robertsi_.

On June 22 and 23, 1955, four clutches of eggs of this species were found beneath adobe bricks and rocks on the volcanic ash that has buried the village of San Juan de Parangaricutiro. The eggs were unstalked and separate, but adherent in clumps of three or four (Pl. 2, Fig. 1). The outer membranes were covered with fine particles of ash. The ash beneath the stones where the eggs were found was only slightly moist; one clump of eggs was partially desiccated. Three complete clutches have 20, 23, and 34 eggs; one clutch of 15 eggs was being eaten by beetles (Tenebrionidae: _Eleodes_ sp.). The eggs vary in size from 4.6 to 6.5 mm. and average 5.3 mm. in diameter. They are unpigmented. Surrounding the embryo is a vitelline membrane, an inner, and an outer envelope (Fig. 1). In an average-sized egg having an embryo 4 mm. in length, the diameter of the outer membrane is 5.3 mm., the inner membrane 5.0 mm., and the vitelline membrane 4.6 mm. All of the eggs contained embryos in which the limb buds were developed; in about half of these the eyes were distinctly visible.

[Ill.u.s.tration: Fig. 1. Diagram of an egg of _Pseudoeurycea belli_ from San Juan de Parangaricutiro, Michoacan. 10.]

The first heavy rain of the season occurred on the night of June 22, 1955. Thus, at least sometimes, _Pseudoeurycea belli_ lays its eggs before the onset of the rainy season. A female having a snout-vent length of 110 mm., collected on June 22, 1955, contained 36 ovarian eggs having diameters from 3.0 to 3.5 mm. The fact that small juveniles were collected on the same date indicates that this salamander lays eggs over a period of several weeks in late spring and early summer.

The smallest juvenile examined has a snout-vent length of 17.0 mm. and a tail length of 7.5 mm. Twelve juveniles from the vicinity of San Juan de Parangaricutiro have an average snout-vent length of 19.4 mm. and an average tail length of 9.7 mm. In juveniles the adpressed limbs either touch or overlap by one intercostal s.p.a.ce; in adults there are two or three intercostal s.p.a.ces between adpressed toes. Therefore the greatest number of intercostal s.p.a.ces between adpressed limbs is found in the largest specimens. A similar relations.h.i.+p between adpressed limbs (= length of limbs) and snout-vent length was shown for _Plethodon richmondi_ by Duellman (1954a). The number of vomerine teeth is variable; the number of teeth seems to be closely correlated with the size of the salamander (Fig. 2). A similar correlation between the number of maxillary teeth and body length was reported for _Chiropterotriton multidentatus_ by Rabb (1958). In 12 juvenile _Pseudoeurycea belli_ there are 6-13 (8.8) vomerine teeth, and in 11 adults having snout-vent lengths greater than 90 mm. there are 39-49 (44.0) vomerine teeth. The coloration of the juveniles resembles that of the adults (Pl. 1).

[Ill.u.s.tration: FIG. 2. Correlation between the number of vomerine teeth and snout-vent length in 79 _Pseudoeurycea belli_ from Michoacan.]

The differences between this species and _Pseudoeurycea gigantea_ are minor. Taylor (1939a) distinguished _gigantea_ from _belli_ by the larger size, fewer intercostal s.p.a.ces between adpressed limbs, more vomerine teeth, and absence of occipital spots in _gigantea_. Taylor and Smith (1945) stated that in life the spots in _gigantea_ are orange instead of red as in _belli_. Five specimens of _Pseudoeurycea belli_ from Michoacan, including one juvenile, lack occipital spots. In the 34 living individuals that I have seen from Michoacan the spots varied from deep red to orange. Therefore, of the characters listed by Taylor (_op.

cit._) to diagnose _Pseudoeurycea gigantea_, only the over-all larger size and smaller number of intercostal s.p.a.ces between adpressed limbs (= relatively longer limbs) are useful in separating _Pseudoeurycea belli_ and _gigantea_.

~Pseudoeurycea robertsi~ (Taylor)

_Oedipus robertsi_ Taylor, Univ. Kansas Sci. Bull., 25:287, July 10, 1939.--Nevado de Toluca, Mexico.

_Pseudoeurycea robertsi_ Taylor, Univ. Kansas Sci. Bull., 30:209, June 12, 1944.

Atzimba (3); Macho de Agua (9); Puerto Lengua de Vaca (14).

Previously this species has been recorded only from the type locality.

In July, 1956, individuals referable to this species were found at two sites in pine-fir forest immediately to the east of Macho de Agua and in pine-oak-fir forest at Atzimba. On August 20, 1958, a series was collected in pine-fir forest at Puerto Lengua de Vaca. These localities are between 2900 and 3000 meters in the Cordillera Volcanica in eastern Michoacan.

In life the coloration of these salamanders was highly variable. The belly and undersurfaces of the tail and hind limbs were pale gray, with or without silvery white flecks; the chin was a cream-color and flecked with silvery white in some specimens. The middorsal area was brown, orange-brown, or dull grayish yellow. The flanks and lateral surfaces of the tail were black with yellowish flecks or streaks on the flanks and yellowish or orange-brown flecks on the tail. The iris was golden brown.

Measurements of eight males and two females are, respectively: snout-vent length, 42.5-56.0 (49.5), 54.0-60.0 (57.0); tail length, 42.0-56.0 (48.1), 52.0-55.0 (53.5). The smallest juvenile has a snout-vent length of 28.0 mm. and a tail length of 23.0 mm. Of the 26 available specimens, six have 12 costal grooves, and the others have 11.

In comparison with 36 topotypes, the specimens from Michoacan have a less striking dorsal color pattern; none has a well-defined dorsal reddish brown area or bold reddish mottling on the tail. Furthermore, the specimens from Michoacan have paler venters than do topotypic specimens.

Salientia

~Rhinophrynus dorsalis~ Dumeril and Bibron

_Rhinophrynus dorsalis_ Dumeril and Bibron, Erpetologie generale, vol. 8:758, 1841.--Veracruz, Veracruz, Mexico.

Mouth of the Rio Balsas (10).

These specimens (BMNH 1914.1.28.181-90) were collected by Gadow in 1908 and reported by him (1930:72): "Whilst this very sluggish termite-eating toad is common enough in the sweltering hot country of the state of Vera Cruz, up to an elevation of 1500 feet, it was unknown on the west side of the Isthmus until I found it in great numbers near the mouth of the Balsas River, in and near fresh-water pools, where it attracted attention by its loud peculiar voice during the pairing season in the month of July." Subsequently, Peters (1954:3) verified the identification of these specimens. Although torrential rains fell during the week in July, 1955, that I spent at Playa Azul near the mouth of the Rio Balsas, the distinctive voice of _Rhinophrynus_ was not heard.

Elsewhere on the Pacific coast of Mexico adult _Rhinophrynus_ have been reported only from Tehuantepec and a few localities on the coastal lowlands of Chiapas. Taylor (1942b:37) found on the coast of Guerrero a tadpole that was referred to the genus _Rhinophrynus_ by Orton (1943).

In the summer of 1960 adults of _Rhinophrynus_ were collected near Acapulco, Guerrero (Fouquette, _in litt._). These recent collections verify the existence of the species along the Pacific lowlands of Mexico at least as far north as Michoacan.

~Scaphiopus hammondi multiplicatus~ Cope

_Scaphiopus multiplicatus_ Cope, Proc. Acad. Nat. Sci.

Philadelphia, 15:52, June 8, 1863.--Valley of Mexico.

_Scaphiopus hammondi multiplicatus_, Kellogg, Bull. U. S.

Natl. Mus., 160:22, March 31, 1932.

Angahuan (5); Cuitzeo (4); Cuseno Station (2); Jiquilpan (9); Morelia (7); Patzcuaro (3); Quiroga; Tarecuaro; Uruapan (24); Zacapu.

This small toad has been found at elevations between 1500 and 2500 meters on the Mexican Plateau and a.s.sociated mountain ranges; it occurs in mesquite-gra.s.sland and in pine forests. Calling males and females laden with eggs have been collected in the rainy season in the months of July and August. The call is a medium-pitched snore. In living individuals the dorsal ground color varies from pale brown to gray with dark brown or olive-brown markings. In many individuals the tips of the small dorsal pustules are red.

~Bufo coccifer~ Cope

_Bufo coccifer_ Cope, Proc. Acad. Nat. Sci. Philadelphia, 18:130, 1866--Arriba, Costa Rica.

Apatzingan (27); Lombardia; Nueva Italia (5).

In life the dorsal color pattern consists of a yellowish tan ground color with dark brown spots; the middorsal stripe is deep yellow or cream color. The venter is a dusty cream color, and the iris is pale gold. Males have dark brown h.o.r.n.y nuptial tuberosities on the thumb. The following measurements are of 21 males and four females, respectively: snout-vent length, 43.5-51.7 (48.1), 55.6-62.6 (59.1); tibia length, 16.6-18.8 (17.6), 18.8-20.3 (19.3); head width, 16.7-19.7 (18.4), 20.6-22.2 (21.4); head length, 13.8-16.6 (14.8), 16.5-18.2 (17.3).

The specimens from the Tepalcatepec Valley differ slightly from specimens from southeastern Mexico and Central America. Those from Michoacan have low and narrow cranial crests; in about one-half of the specimens the occipital crest exists only as a row of tubercles, and in some the pos...o...b..tal and suborbital crests are barely discernible.

Specimens from the southern part of the range, Costa Rica and Nicaragua, have much higher and thicker cranial crests; in these the occipital crest is well defined and extends posteriorly to a point back of the anterior edge of the parotid gland; the pos...o...b..tal and suborbital crests are well marked. Of 48 specimens from Esquipulas, Guatemala, all have high crests, but these are not so well developed as in ten specimens from Matagalpa, Nicaragua, and three from various localities in Costa Rica. Six specimens from Tehuantepec, Oaxaca, have cranial crests that are lower than those in specimens from Guatemala. In three of the specimens from Tehuantepec the occipital crests are reduced to a series of tubercles. Of six specimens from Agua del Obispo, Guerrero, four have poorly developed occipital crests. These observations suggest the presence of a cline in the development of the cranial crests; specimens have higher crests in the southern part of the range than in the northern part.

In Mexico _Bufo coccifer_ has been collected only in semi-xeric habitats, but to the south, from Guatemala to Costa Rica, it has been found in more upland and humid habitats. Southern specimens are darker than those from the north, a possible correlation with the differences in habitat.

These toads probably range throughout the Tepalcatepec Valley, but they are unknown from the coast of Michoacan. Breeding choruses were found after heavy rains on June 24, 1955, and on August 2, 1956. The first was in a muddy ditch; the second was in a flooded gra.s.sy field. The call is a high-pitched, but not loud, "whirrr." Males were calling from the edge of the water or from clumps of gra.s.s in the water. Clasping pairs were in the water; amplexus is axillary.

~Bufo compactilis compactilis~ Wiegmann

_Bufo compactilis_ Wiegmann, Isis von Oken, 26:661, 1833.--Mexico. Type locality restricted to Xochimilco, Distrito Federal, Mexico, by Smith and Taylor (1950a:330).

_Bufo compactilis compactilis_, Smith, Herpetologica, 4:7, September 17, 1947.

Cuitzeo (2); Emiliano Zapata (20); Jiquilpan (5); La Palma (5); Morelia; Tupataro.