Part 4

Most of the 78 species of amphibians and reptiles definitely known from the rainforest in southern El Peten have extensive ranges in the Atlantic lowlands of southern Mexico and Central America; many extend into South America. Sixty-two (80%) of the species belong to this group having extensive ranges in Middle America. Three species (Syrrhophus leprus, Leptodeira frenata, and Kinosternon acutum) are at the southern limits of their distributions in southern El Peten and northern Alta Verapaz, whereas Eleutherodactylus rostralis and Thecadactylus rapicaudus are at the northern and western limits of their distributions in El Peten. Nine (11%) species have the center of their distributions in El Peten and the Yucatan Peninsula; representatives of this group include Claudius angustatus, Dermatemys mawi, Laemanctus deborrei, and Eumeces schwartzei.

In determining a measure of faunal resemblance, I have departed from the formulae discussed by Simpson (1960) and have analyzed the degree of resemblance by the following formula used to calculate an index of faunal relationships:

C (2) / (N{1} + N{2}) = R, where

C = species common to both faunas.

N_{1} = number of species in the first fauna.

N_{2} = number of species in the second fauna.

R = degree of relationships (when R = 1.00, the faunas are identical; when R = 0, the faunas are completely different).

The herpetofauna of southern El Peten has been compared with that in the Tikal-Uaxactun area (Stuart, 1958), that in the humid lowlands of Alta Verapaz (Stuart, 1950, plus additional data), and that in the Mexican state of Yucatan (Smith and Taylor, 1945, 1948, and 1950). The herpetofaunas of lowland Alta Verapaz and Yucatan are the largest, having respectively 94 and 91 species, where as there are 78 species known from southern El Peten and 64 from the Tikal-Uaxactun area. An analysis of faunal relationships (Table 2) shows that the faunas of the rainforests of southern El Peten and lowland Alta Verapaz are closely related. The relationships between these two areas and the Tikal-Uaxactun area in northern El Peten is notably less. Apparently the biggest faunal changes take place between southern El Peten and the Tikal-Uaxactun area, and between the latter and Yucatan. As stated by Stuart (1958:7) the Tikal-Uaxactun is transitional between the humid rainforests to the south and the dry outer end of the Yucatan Peninsula. The transitional nature of the environment is exemplified by a rather depauperate herpetofauna consisting of some species of both dry and humid environments and lacking a large fauna typical of either. Contrariwise, the continuity of the environment from southern El Peten to the lowlands of Alta Verapaz is reflected in degree of resemblance of the herpetofaunas.

TABLE 2.--INDEX OF FAUNAL RELATIONSHIPS BETWEEN SOUTHERN EL PETEN AND OTHER REGIONS.

======================+==========+==========+==========+========== | Lowland | Southern | Tikal- | | Alta | El | Uaxactun | Yucatan | Verapaz | Peten | Area | ----------------------+----------+----------+----------+---------- Lowland Alta Verapaz | | .85 | .61 | .43 ----------------------+----------+----------+----------+---------- Southern El Peten | .85 | | .64 | .41 ----------------------+----------+----------+----------+---------- Tikal-Uaxactun Area | .61 | .64 | | .63 ----------------------+----------+----------+----------+---------- Yucatan | .43 | .41 | .63 | ----------------------+----------+----------+----------+----------

Most of the species of amphibians and reptiles found in southern El Peten are found in humid tropical forests from the Isthmus of Tehuantepec southeastward on the Atlantic lowlands well into Central America.

ACCOUNTS OF SPECIES

In the following pages various aspects of the occurrence, life histories, ecology, and variation of the species of amphibians and reptiles known from southern El Peten are discussed. Only Cochranella fleischmanni reported by Stuart (1937) from Rio Subin at Santa Teresa was not collected by us and is excluded. Because more worthwhile information was gathered for some species than others, the length and completeness of the accounts vary. All specimens listed are in the Museum of Natural History at the University of Kansas, to which institution all catalog numbers refer. Preceding the discussion of each species is an alphabetical list of localities from which specimens were obtained; numbers after a locality indicate the number of specimens obtained at each locality.

=Bolitoglossa dofleini= (Werner)

Chinaja, 1.

An adult female having minute ovarian eggs has a snout-vent length of 81 mm., a tail length of 59 mm., 13 costal grooves, two intercostal spaces between adpressed toes, 38-35 vomerine teeth in irregular rows forming a broad arch from a point posterolaterad to the internal nares to a point near the anterior edge of the parasphenoid teeth, and 43-44 maxilliary-premaxillary teeth. In life the dorsum was rusty brown with irregular black and orange spots and streaks. The flanks were bluish gray with black in the costal grooves and creamy tan flecks along the ventral edge of the flank. The belly and underside of the tail were yellowish tan with dark brown spots laterally. The limbs were orange proximally and black distally; the pads of the feet were bluish black. The dorsal and lateral surfaces of the tail were yellowish orange with black spots. The iris was grayish yellow.

Stuart (1943:17) reported this species from Finca Volcan, Alta Verapaz. He diagnosed his specimens as having 13 costal grooves and two or three intercostal spaces between adpressed toes. He stated that the vomerine teeth were about 12 in number and that in life the dorsum was mottled gray and black, the sides gray and brown, and the undersurfaces uniformly dark gray. These specimens differ noticeably from the individual from Chinaja in the number of vomerine teeth and in coloration.

In August, 1961, I obtained a specimen of Bolitoglossa dofleini at Finca Los Alpes, Alta Verapaz, approximately 13 kilometers airline south-southwest of Finca Volcan and at approximately the same elevation. Although the salamander was dead when found, it obviously was more heavily pigmented than the individual from Chinaja. The belly was bluish gray with black spots laterally; the dorsum was dull brownish gray with some brownish red streaks. The specimen is a female having small ovarian eggs, a snout-vent length of 90 mm., 13 costal grooves, and two intercostal spaces between adpressed limbs. There are 28-29 vomerine teeth, more than twice as many as in specimens from Finca Volcan (Stuart, 1943:17), but noticeably fewer than in the specimen from Chinaja.

The presence of this species at Chinaja lends support to the idea that the specimen from the Rio de la Pasion listed by Brocchi (1882:116) also is Bolitoglossa dofleini. Furthermore, the confirmed presence of this species in the lowlands of El Peten suggests that there may be genetic connection between B. dofleini in the Alta Verapaz and B. yucatana in the Yucatan Peninsula. Bolitoglossa yucatana differs from B. dofleini in having five intercostal spaces between adpressed toes and in having a different color pattern. Both are robust species having no close relationships to other species of Bolitoglossa in northern Central America.

The specimen from Chinaja was found in water in the axil of a large elephant-ear plant (Xanthosoma) by day in March. Its stomach contained fragments of beetles and a large roach. The natives did not know salamanders and had no name for them.

=Bolitoglossa moreleti mulleri= (Brocchi)

Chinaja, 2; Rio San Roman, 1.

One specimen is a female having a snout-vent length of 80 mm., a tail length of 82 mm., and a total length of 162 mm. It contains 63 large eggs, the largest of which has a diameter of about three millimeters. This specimen has 13 costal grooves, four intercostal spaces between adpressed toes, and 12-13 vomerine teeth. A juvenile having a snout-vent length of 39 mm. and a tail length of 33 mm. has 12 costal grooves, three intercostal spaces between adpressed toes, and 8-8 vomerine teeth. In life these salamanders were uniformly dull brownish black above with a dull creamy yellow irregular dorsal stripe beginning on the occiput and continuing onto the tail. There are no yellow or orange streaks or flecks on the head or limbs. The specimen from the Rio San Roman was taken from the stomach of a Pliocercus euryzonus aequalis and has not been studied in detail, because of its poor condition.

The present specimens show no tendency for the development of a broad irregular dorsal band that encloses black spots or forms irregular dorsolateral stripes, as is characteristic of B. moreleti mexicanus, a subspecies that has been reported from La Libertad (Stuart, 1935:35) and Piedras Negras (Taylor and Smith, 1945:545) in El Peten, and from Xunantunich, British Honduras (Neill and Allen, 1959:20).

Schmidt (1936:151) and Stuart (1943:13) found B. moreleti mulleri in bromeliads at Finca Samac, Alta Verapaz. Taylor and Smith's (1945:545) and Neill and Allen's (1959:20) specimens of B. moreleti mexicanus were obtained from bromeliads, but Neill and Allen (loc. cit.) stated that the natives in British Honduras said that they had found salamanders beneath rubbish on the forest floor. My specimens were obtained from beneath logs on the forest floor in the rainy season. Possibly in drier environments the species characteristically inhabits bromeliads, at least in the dry season.

=Bufo marinus= (Linnaeus)

Chinaja, 3; 10 km. NNW of Chinaja, 1; 11 km. NNW of Chinaja, 1.

During both visits to Chinaja this large toad was breeding in a small permanent pond in the camp. During the day the toads took refuge in crevices beneath the buildings or beneath large boulders by the pond. At dusk from four to ten males congregated at the pond and called. Tadpoles of this species were in the pond in March and in July. One juvenile was found beneath a rock in the forest, and another was on the forest floor by day.