The Amphibians and Reptiles of Michoacan, Mexico Part 4

Aguililla (2); Apatzingan (42); Buena Vista (5); Capirio (3); La Playa (25); Lombardia (6); Nueva Italia (9); Rio Cancita, 14 km. E of Apatzingan; Rio Tepalcatepec, 27 km. S of Apatzingan; San Salvador (4); Tzitzio; Volcan Jorullo.

~Bufo occidentalis~ Camerano

_Bufo occidentalis_ Camerano, Atti R. Accad. Sci. Torino, 14:887, December 31, 1878.--Mexico. Type locality restricted to Guanajuato, Guanajuato, Mexico, by Smith and Taylor (1950a:330). Firschein, Copeia, no. 3:220, September 15, 1950.

_Bufo simus_, Smith and Taylor, Bull. U. S. Natl. Mus., 194:42, 1948.

Barranca Seca (32); Cerro de Barolosa (4); Cerro Tancitaro, 3 km. E of Apo (2); Cerro Tancitaro, 19 km. E. of Apo (10); Charapendo; Coalcoman (7); Dos Aguas (4); Jacona, Jaramillo (2); Las Tecatas; Los Reyes (181); Tancitaro (10); Uruapan (3).

This toad is an inhabitant of pine and oak forests between 900 and 2400 meters. Near Charapendo on the slopes of the Sierra de los Tarascos and at Coalcoman it apparently reaches its lowest alt.i.tudinal limits. At both of these localities the pine-oak forest is replaced by arid tropical scrub forest on the lower slopes.

Twenty-four tadpoles were collected on May 3 in a quiet section of a fast stream near Barranca Seca. The tadpoles have a robust body, broadest about two-thirds the distance from the snout to the posterior edge of the body, half again as broad as deep. Eyes dorsolateral; nostrils dorsal, somewhat directed forward, and about three-fifths the distance from the tip of the snout to the eye; spiracle sinistral and lateral, located at about midbody; a.n.u.s median; tail long and slender; tail-musculature extends nearly to tip of tail; depth of tail-musculature at mid-length about one-third total depth of tail; dorsal tail-fin not extending onto body (Fig. 5); average body length of ten tadpoles having small hind limb buds, 14.4 mm.; average tail length, 22.0 mm.

Mouth ventral, nearly terminal, about one-third as wide as widest part of body; anterior lip has no papillae; lower lip bordered by two rows of papillae and lateral lips by one row of papillae; beaks moderately well developed, the upper forming a broad arch and finely denticulate; tooth rows 2/3, the upper rows extending to the edge of the lips, subequal in length, and slightly longer than lower rows, which also are subequal in length; inner upper tooth row broken medially; inner lower tooth row sometimes broken (Fig. 6).

The body is black dorsally and laterally, and bluish gray ventrally; the tail musculature is brown and stippled with darker brown. The fins are transparent and stippled with brown, the stippling being most p.r.o.nounced on the posterior two-thirds of the upper tail-fin.

[Ill.u.s.tration: FIG. 5. Tadpole of _Bufo occidentalis_ (UMMZ 94269) from Barranca Seca, Michoacan. 3.]

[Ill.u.s.tration: FIG. 6. Mouthparts of larval _Bufo occidentalis_ (UMMZ 94269) from Barranca Seca, Michoacan. 20.]

Forty recently metamorphosed individuals average 18.9 mm. in snout-vent length.

The relations.h.i.+ps of this toad seem to be with _Bufo bocourti_ Brocchi, an inhabitant of pine and oak forests in the uplands of Chiapas and Guatemala. In _Bufo occidentalis_ the tympanum usually is indistinct and sometimes completely covered, and it is absent in _bocourti_. _Bufo occidentalis_ has a broader interorbital area and relatively shorter and more rounded parotid glands than _bocourti_. The tadpoles of the two species are nearly identical (see Stuart, 1943:12).

~Leptodactylus l.a.b.i.alis~ (Cope)

_Cystignathus l.a.b.i.alis_ Cope, Proc. Amer. Philos. Soc., 17:90, 1877.--No type locality designated; type locality restricted to Potrero Viejo, Veracruz, Mexico, by Smith and Taylor (1950a:350).

_Leptodactylus l.a.b.i.alis_, Brocchi, Mission Scientifique au Mexique et dans l'Amerique Centrale, pt. 3, sec. 2, livr.

1:20, 1881.

Apatzingan (26); Capirio (5); Cofradia (9); El Sabino (4); Lombardia; Rio Tepalcatepec, 27 km. S of Apatzingan (2).

In the Tepalcatepec Valley this frog reaches the northernmost known limit of its range in western Mexico. Although the species is abundant in the valley, it apparently is absent from the coastal lowlands. In the Tepalcatepec Valley _Leptodactylus melanonotus_ seems to be more abundant than _l.a.b.i.alis_. In the rainy season both species have been heard calling from the same ponds and flooded fields.

There are only slight differences in size between the s.e.xes; measurements of 20 males and eight females are, respectively: snout-vent length, 32.3-39.5 (35.1), 34.1-39.2 (37.2); tibia length, 14.3-17.0 (15.4), 14.9-16.8 (15.8); head width, 11.0-13.6 (12.0), 12.2-13.2 (12.6); head length, 12.8-15.1 (13.3), 12.8-14.6 (13.7).

~Leptodactylus melanonotus~ (Hallowell)

_Cystignathus melanonotus_ Hallowell, Proc. Acad. Nat. Sci.

Philadelphia, 12:485, 1861.--Nicaragua. Type locality restricted to Recero, Nicaragua, by Smith and Taylor (1950a:320).

_Leptodactylus melanonotus_, Brocchi, Mission Scientifique au Mexique et dans l'Amerique Centrale, pt. 3, sec. 2, livr.

1:20, 1881.

Apatzingan (103); Capirio; Charapendo (7); Coahuayana; Cofradia (10); El Sabino (21); La Playa (3); Lombardia (5); Maruata; Nueva Italia (7); Ostula (9); Playa Azul (11); Rio Marquez, 10 km. S of Lombardia; Rio Marquez, 13 km. SE of Nueva Italia (6); Rio Tepalcatepec, 27 km. S of Apatzingan.

This species is widespread in the lowlands of the state; it has been collected up to elevations of 1050 meters in the Tepalcatepec Valley. In the dry season individuals were discovered beneath rocks along streams and in damp arroyos; in the rainy season they were found wherever there was water. Males were heard calling from flooded fields, ditches, rocky streams, and small puddles. The call is a series of individual notes: "woink, woink, woink."

Adult males are noticeably smaller than females; measurements for 20 males and ten females from Apatzingan are, respectively: snout-vent length, 29.6-34.6 (32.3), 36.3-44.1 (40.8); tibia length, 12.6-15.1 (14.0), 16.5-19.0 (17.8); head width, 10.8-11.9 (11.3), 12.6-14.8 (13.7); head length, 11.2-13.2 (11.9), 13.1-14.8 (14.0). Brownish yellow ventral glands are present in some juveniles and in some adults collected in the dry season as well as in the rainy season.

~Leptodactylus occidentalis~ Taylor

_Leptodactylus occidentalis_ Taylor, Trans. Kansas Acad.

Sci., 39:349, 1937.--Tepic, Nayarit, Mexico.

Five km. W of Tangamandapio.

On the night of June 11, 1958, this species was calling from a hyacinth-choked ditch. Although numerous individuals were heard, only one specimen was obtained. The frogs were calling from the tangled mat of hyacinths along with _Hyla eximia_, _Hypopachus oxyrrhinus ovis_, and _Rana pipiens_.

Taylor (1936a:352) characterized this species as follows: "The narrow head, small maximum size (38 mm. for females, 33 mm. for males), the character of the postaxillary and postfemoral glands, the narrower groups of vomerine teeth, clearly distinguish this western Mexican form from the more robust, larger _melanonotus_ to the south. The call is likewise fainter and different in quality." Concerning the glands, Taylor (_loc. cit._) remarked: "There is a possibility that the h.o.r.n.y excrescence covering the glands may appear only during the breeding season. This character is quite as strongly marked in females as in males." Bogert and Oliver (1945:324) concluded that the population of _Leptodactylus_ in northwestern Mexico could not be distinguished from _melanonotus_ in other parts of the country and thus synonymized _Leptodactylus occidentalis_ with _melanonotus_. Bogert and Oliver (op.

cit.: 324) stated that the extent as well as the presence or absence of ventral glands was highly variable in all samples examined by them.

Upon seeing numerous living individuals of _Leptodactylus melanonotus_ from many parts of its range in Mexico and individuals of the population of _Leptodactylus_ in northwestern Mexico (Nayarit and Sinaloa), I was immediately impressed not so much by the differences in the development of the ventral glands, but by the color of the glands. The differences in color are apparent in freshly preserved specimens. With the exception of _Leptodactylus_ from northwestern Mexico, specimens of _melanonotus_ from throughout Mexico and northern Central America have yellow or yellowish brown glands. Specimens from northwestern Mexico have black or brownish black glands that are conspicuously darker than those found in _melanonotus_. Examination of 653 preserved specimens of _Leptodactylus melanonotus_ from Mexico and Guatemala has failed to reveal specimens with black ventral glands, like those found in specimens from northwestern Mexico, to which the name _Leptodactylus occidentalis_ has been applied. Furthermore, in _melanonotus_ the glands are less distinct and more extensive than in _occidentalis_; in the latter species glands are absent from the throat and midventral area, where they often are present in _melanonotus_ (Fig. 7).

In some individuals of both species collected in the dry season and in some collected in the rainy (breeding) season the glands are absent; the development of these glands, therefore, does not seem to be correlated with breeding. Likewise, the glands are present or absent in either s.e.x, and often as not they are present in juveniles. Presence of the glands, therefore, cannot be correlated either with s.e.xual or ontogenetic development. Since the glands are found in individuals from all parts of the range, it is unlikely that there is a correlation between the development of the glands and the environment.

[Ill.u.s.tration: FIG. 7. Diagrammatic view of ventral surfaces of _Leptodactylus melanonotus_ (A) and _Leptodactylus occidentalis_ (B), showing usual position and size of glandular areas. Approx. natural size.]

Aside from the differences in the ventral glands, the call is different in the two populations. The call of _Leptodactylus occidentalis_ is a rather harsh "wack, wack, wack" as contrasted with the more nasal "woink, woink, woink" of _melanonotus_. Sound spectrographs are needed to a.n.a.lyze the differences in calls. None of the specimens of _occidentalis_ examined approaches in size the largest individuals of _melanonotus_; possibly the size of the frogs is another valid character for separating the species. On the basis of the above data it is evident that the frogs in northwestern Mexico show certain characters that distinguish them from _Leptodactylus melanonotus_, as it is known throughout the rest of Mexico. It is not known for certain that _melanonotus_ and _occidentalis_ are sympatric. Several series of old, poorly preserved specimens from Nayarit and Sinaloa cannot be placed in either species, for none has visible ventral glands. _Leptodactylus melanonotus_ is known from Acaponeta, Nayarit (AMNH 43913-25), and the following localities in Jalisco: Barro de Navidad (UMMZ 118098), La Concepcion (UMMZ 113081), La Resolana (UMMZ 102104), and Tenachitlan (UMMZ 113045-6). Records for _Leptodactylus occidentalis_ are: alamos, Sonora (AMNH 51356-65); Culiacan (AMNH 49511-9), Chele (UMMZ 110914), and Rosario (UMMZ 113062) in Sinaloa; Ixtlan del Rio (UMMZ 102108), San Blas (UMMZ 112814, 112994, 110892, 115543), and Tepic (UMMZ 115544) in Nayarit; Ameca (UMMZ 102106-7) and La Cofradia on the south sh.o.r.e of Lago de Chapala (UMMZ 102105) in Jalisco; and Tangamandapio, Michoacan (UMMZ 119145). From these scattered records it appears that _Leptodactylus occidentalis_ in the southern part of its range stays in the uplands, whereas _melanonotus_ is confined to the lowlands.

~Microbatrachylus hobartsmithi~ (Taylor)

_Eleutherodactylus hobartsmithi_ Taylor, Trans. Kansas Acad.

Sci., 39:355, 1937.--Uruapan, Michoacan, Mexico.

_Microbatrachylus hobartsmithi_ Taylor, Univ. Kansas Sci.

Bull., 26:501, November 27, 1940.

Cascada Tzararacua (6); 21 km. W of Ciudad Hidalgo; 29 km. E of Morelia; Puerto Hondo; San Jose de la c.u.mbre (13); Uruapan (2); Zitacuaro.

Of six specimens from Cascada Tzararacua, five are colored like typical _M. hobartsmithi_, having the anterior and posterior surfaces of the thighs and the upper arms pale pink in life and a grayish brown dorsum in preservative. The other specimen (UMMZ 94231) has in preservative a dark brown dorsolateral line on each side enclosing a pale tan area that extends from the snout to the vent. One specimen from 29 kilometers east of Morelia (UIMNH 40338) and 13 specimens from San Jose de la c.u.mbre (UMMZ 102111) do not have the prominent tarsal tubercles characteristic of _M. hobartsmithi_. Also, in these fourteen specimens the palmar tubercles are larger, and the dark a.n.a.l patch more distinct, than in typical _M. hobartsmithi_. Possibly these specimens, which are from the high mountains in the eastern part of Michoacan, represent another species of _Microbatrachylus_. However, Taylor (1940d:501) reported a series of _M. hobartsmithi_ from the mountains 10 miles west of Villa Victoria in the western part of the state of Mexico.

The largest specimen from Michoacan is a gravid female (UIMNH 16104) having a snout-vent length of 23.5 mm.

_Microbatrachylus hobartsmithi_ has been found in rocky ravines along streams in the Cordillera Volcanica and the southwestern escarpment of these mountains at elevations from 1450 to 2750 meters.

~Microbatrachylus pygmaeus~ (Taylor)

_Eleutherodactylus pygmaeus_ Taylor, Trans. Kansas Acad.