The Amphibians and Reptiles of Michoacan, Mexico Part 3

The southwestern terminus of the range of this species is on the Mexican Plateau in Michoacan. All specimens from the state have spotted venters.

In living toads the dorsal ground color was gray or grayish tan with olive green spots. The vocal sac was brownish gray; the iris was a bright golden color.

On June 11, 1958, many individuals were calling from shallow water in a flooded field at Emiliano Zapata. The call is a slow trill, in which the individual notes are discernible.

~Bufo marinus~ (Linnaeus)

_Rana marina_ Linnaeus, Systema naturae, ed. 10, 1:211, 1758.--America.

_Bufo horribilis_ Wiegmann, Isis von Oken, 26:654, 1833.--Misantla and Veracruz, Veracruz, Mexico. Taylor and Smith, Proc. U. S. Natl. Mus., 95:551, January 30, 1945.

_Bufo angustipes_ Taylor and Smith, Proc. U. S. Natl. Mus., 95:553, January 30, 1945.--La Esperanza, Chiapas, Mexico.

Aguililla; Apatzingan (3); Barranca de Bejuco; Capirio; Charapendo; Chichihuas; Coahuayana (2); Coalcoman (7); Cofradia (2); 25 km. S of Cuatro Caminos; El Sabino (10); Huahua, La Playa (13); Ojos de Agua de San Telmo; Ostula; Playa Azul (2); Pomaro (2).

This large toad is characteristically found in areas supporting tropical scrub forest to elevations of about 1000 meters. The species is much more abundant than the numbers listed above suggest. In the dry season individuals have been observed in patios, along streams, and by irrigation ditches. In the rainy season the loud, rattling call of the males is heard at night throughout the Tepalcatepec Valley and the coastal lowlands.

Taylor and Smith (1945:552) revived Wiegmann's _Bufo horribilis_ for the large toads of Mexico that are here referred to _B. marinus_. Their action was based upon the supposition that the "species _marinus_" is composite. Although probably true, this supposition has yet to be proved. Until the large, and apparently related, species of _Bufo_ inhabiting tropical America have been studied systematically as a unit, the recognition of segments of the population as either species or subspecies is meaningless. Taylor and Smith (op. cit.:553) based the description of a new species, _Bufo angustipes_, on one rather emaciated, formalin-hardened female from La Esperanza, Chiapas. The type (USNM 116513), when compared with numerous specimens of _Bufo marinus_ from throughout the range of the species in Mexico and northern Central America, displays no combination of characters to set it off from the others. Therefore, I suggest that _Bufo horribilis_ Wiegmann and _Bufo angustipes_ Taylor and Smith be placed in the synonymy of _Bufo marinus_ (Linnaeus) until future systematic study of the genus and this species in particular establishes the existence of recognizable taxa.

~Bufo marmoreus~ Wiegmann

_Bufo marmoreus_ Wiegmann, Isis von Oken, 26:66, 1833.--Veracruz, Veracruz, Mexico.

Barranca de Bejuco; Coahuayana (11); El Diezmo (2); La Placita (9); La Orilla (12); Motin del Oro; Ostula (9); Playa Azul (5); Pomaro (15); Salitre de Estopilas; San Pedro Naranjestila.

In Michoacan this species is confined to elevations of less than 1000 meters on the coast and foothills of the Sierra de Coalcoman. In this region in the months of June and July, breeding congregations have been found in temporary pools and along streams.

Smith and Taylor (1948:39), in their key to the Mexican species of _Bufo_, placed emphasis on the nature of the supraorbital and pos...o...b..tal crests (whether they form a curve or a sharp angle) in distinguishing _Bufo marmoreus_ from _Bufo perplexus_. In the original description of _perplexus_, Taylor (1943a:347) characterized the species as follows: supraorbital and pos...o...b..tal crests forming a sharp angle, instead of a curve as in _marmoreus_; supratympanic crest smaller than in _marmoreus_; diagonal lateral stripe lacking in females; concentration of dorsal tubercles as found in _marmoreus_ lacking in males. The discovery of specimens in which the crests form a curve and others in which the crests form an angle in both the Tepalcatepec Valley and in the coastal lowlands prompted an investigation of these characters and others throughout the ranges of the species. An examination of 410 specimens has resulted in the following conclusions.

TABLE 1.--VARIATION IN THE SHAPE OF THE SUPRAORBITAL AND POs...o...b..TAL CRANIAL CRESTS IN BUFO MARMOREUS AND B. PERPLEXUS.

+------------------------+---+-----------+------------+----------+ |LOCALITY | N | Curved |Intermediate| Angular | +------------------------+---+-----------+------------+----------+ |Tepalcatepec Valley | 50| 10 (20.0%)| 17 (34.0%) |23 (46.0%)| +------------------------+---+-----------+------------+----------+ |Morelos | 12| 2 (16.6%)| 5 (41.7%) | 5 (41.7%)| +------------------------+---+-----------+------------+----------+ |Izucar, Puebla | 4| 2 (50.0%)| 0 (0.0%) | 2 (50.0%)| +------------------------+---+-----------+------------+----------+ |Southern Sinaloa | 1| 1(100.0%)| 0 (0.0%) | 0 (0.0%)| +------------------------+---+-----------+------------+----------+ |Puerto Vallarta, Jalisco| 2| 2(100.0%)| 0 (0.0%) | 0 (0.0%)| +------------------------+---+-----------+------------+----------+ |Colima | 45| 25 (55.0%)| 18 (40.0%) | 2 (5.0%)| +------------------------+---+-----------+------------+----------+ |Coast of Michoacan | 55| 35 (63.6%)| 17 (30.9%) | 3 (5.5%)| +------------------------+---+-----------+------------+----------+ |Acapulco, Guerrero | 7| 7(100.0%)| 0 (0.0%) | 0 (0.0%)| +------------------------+---+-----------+------------+----------+ |Chilpancingo, Guerrero | 10| 1 (10.0%)| 4 (40.0%) | 5 (50.0%)| +------------------------+---+-----------+------------+----------+ |Pochutla, Oaxaca | 13| 6 (46.2%)| 6 (46.2%) | 1 (7.6%)| +------------------------+---+-----------+------------+----------+ |Tehuantepec, Oaxaca |177| 81 (45.8%)| 67 (37.8%) |29 (16.4%)| +------------------------+---+-----------+------------+----------+ |Tonola, Chiapas | 1| 0 (0.0%)| 0 (0.0%) | 1(100.0%)| +------------------------+---+-----------+------------+----------+ |Veracruz | 33| 26 (78.8%)| 6 (18.2%) | 1 (3.0%)| +------------------------+---+-----------+------------+----------+ | Total |410|198 (48.3%)|140 (34.2%) |72 (17.5%)| +------------------------+---+-----------+------------+----------+

1. Although the highest percentage of individuals having the supraorbital and pos...o...b..tal crests forming a sharp angle is from localities in the Balsas-Tepalcatepec Basin, numerous individuals from throughout the range of _marmoreus_ have the crests forming an angle (Table 1).

2. In all samples of ten or more specimens, some toads have the supraorbital and pos...o...b..tal crests forming a sharp angle, some have the crests forming a curve, and some have an intermediate condition.

3. The relative size of the supratympanic crest is highly variable in all samples examined.

[Ill.u.s.tration: FIG. 3. Adult male of _Bufo perplexus_ from Apatzingan, Michoacan. 1.5.]

[Ill.u.s.tration: FIG. 4. Adult male of _Bufo marmoreus_ from Pomaro, Michoacan. 1.5.]

[Ill.u.s.tration: PLATE 1

Hatchling of _Pseudoeurycea belli_ from San Juan de Parangaricutiro, Michoacan. 8.]

[Ill.u.s.tration: PLATE 2

FIG. 1. Nest and eggs of _Pseudoeurycea belli_ beneath a rock at San Juan de Parangaricutiro. Approx. natural size.

FIG. 2. Multiple egg clutches of _Phyllomedusa dacnicolor_ from Coalcoman, Michoacan. 1/3 .

[Ill.u.s.tration: PLATE 3

FIG. 1. Adult male of _Tomodactylus angustidigitorum_ from Paracho, Michoacan. 4.

FIG. 2. Adult male of _Tomodactylus fuscus_ from Los Cantiles, Michoacan. 4.

[Ill.u.s.tration: PLATE 4

FIG. 1. Adult male of _Tomodactylus nitidus_ nitidus from Tuxpan, Michoacan. .

FIG. 2. Adult male of _Tomodactylus nitidus orarius_ from Tecolapa, Colima. 4.]

[Ill.u.s.tration: PLATE 5

FIG. 1. Adult male of _Tomodactylus nitidus_ petersi from Apatzingan, Michoacan. 4.

Fig. 2. Adult male of _Tomodactylus rufescens_ from Dos Aguas, Michoacan. 4.]

[Ill.u.s.tration: PLATE 6

FIG. 1. Adult male of _Hypopachus caprimimus_ from Tuxpan, Michoacan. 2-1/2.

FIG. 2. Adult male of _Hypopachus oxyrrhinus ovis_ from Tangamandapio, Michoacan. 3.]

4. A distinct, pale-colored, diagonal lateral stripe is found in females only from localities outside of the Balsas-Tepalcatepec Basin; females from the basin have a spotted dorsum.

5. Males from the Balsas-Tepalcatepec Basin usually have a broad middorsal line that is yellow or pale tan; those from outside the basin have either a narrow middorsal line or none.

6. Males from the Balsas-Tepalcatepec Basin have low, scattered dorsal tubercles (Fig. 3); males from outside the basin have a concentration of tubercles in a broad band on the back (Fig. 4).

Therefore the nature of the cranial crests is of little value in separating two populations, but the color pattern of the females and the nature of the dorsal tubercles of the males do show distinct differences. Furthermore, certain differences in size and proportion are evident; _Bufo marmoreus_ is a slightly larger toad and has a relatively longer tibia and longer head than _perplexus_ (Table 2).

TABLE 2.--COMPARISON OF CERTAIN MEASUREMENTS AND PROPORTIONS IN BUFO MARMOREUS AND B. PERPLEXUS. (MEANS ARE GIVEN IN PARENTHESES BELOW THE RANGES.)

+-------------------+------------+--+----------+------------+-----------+ | | | | |Tibia length|Head length| | Species | s.e.x | N|Snout-vent+------------+-----------+ | | | | length | Snout-vent |Snout-vent | | | | | | length | length | +-------------------+------------+--+----------+------------+-----------+ | _B. marmoreus_ | Male |15|61.5-72.5 | 35.9-41.6 | 28.3-33.3 | | | | | (65.2) | (39.0) | (31.6) | +-------------------+------------+--+----------+------------+-----------+ | _B. perplexus_ | Male |20|50.0-59.0 | 33.7-38.1 | 26.4-31.1 | | | | | (54.9) | (36.4) | (29.5) | +-------------------+------------+--+----------+------------+-----------+ | _B. marmoreus_ | Female | 7|68.0-76.0 | 33.0-36.8 | 26.8-32.6 | | | | | (70.7) | (34.7) | (29.6) | +-------------------+------------+--+----------+------------+-----------+ | _B. perplexus_ |Female | 6|64.1-69.8 | 32.4-36.9 | 25.1-29.0 | | | | | (66.8) | (35.5) | (27.5) | +-------------------+------------+--+----------+------------+-----------+

Taylor (1943a:347) described _Bufo perplexus_ from Mexcala on the Rio Balsas in Guerrero. Among the many paratypes are specimens from Tonola, Chiapas, and Tehuantepec, Oaxaca. These apparently were referred to _perplexus_ solely on the nature of the cranial crests. All of the specimens examined during the course of the present study from the lowlands of Veracruz and from the Pacific lowlands from Sinaloa southward to Chiapas are referable to _Bufo marmoreus_; those from the Balsas-Tepalcatepec Basin are referable to _Bufo perplexus_, as defined above. Ten specimens from Chilpancingo, Guerrero (UMMZ 115352), do not readily fit either species. Perhaps there is gene exchange between the inland and coastal populations through the relatively low pa.s.s at Chilpancingo, at the mouth of the Rio Balsas, and near the convergent headwaters of the Rio Coahuayana and Rio Tepalcatepec in southern Jalisco. If this can be demonstrated, then _Bufo perplexus_ would have to be considered as a subspecies of _Bufo marmoreus_, instead of an allopatric species.

~Bufo perplexus~ Taylor

_Bufo perplexus_ Taylor, Univ. Kansas Sci. Bull., 29:347, October 15, 1943.--Balsas River near Mexcala, Guerrero, Mexico.