Throughout the month of July, 1956, Phyllomedusa was breeding in ponds in or adjacent to the rainforest in northern Oaxaca and in southern Veracruz. Only at Alvarado was it found breeding in a grassy pond. Males and females alike were found on bushes and trees in and around the ponds. The call is a single "wank." Amplexing males continue to call, but the call is softer and less nasal in quality. The eggs are encased in pale green gelatin and attached to leaves on branches overhanging the water. Three egg clutches contained 38, 41, and 46 eggs.
Phyllomedusa dacnicolor Cope
Oaxaca: Escurano; Tehuantepec.
Although it is abundant on the Pacific lowlands to the northwest in Guerrero, Michoacán, and Colima, this species is known only from two specimens from Tehuantepec. There is no apparent physical barrier to their distribution in the isthmus; in the Balsas Basin the species lives in a hotter, more arid environment than that at Tehuantepec.
Gastrophryne usta Cope
Oaxaca: Santa Efigenia; Tehuantepec (10); 24 km. W of Tehuantepec; Tolosita (2). Veracruz: Ayentes (6); La Oaxaqueña; Novillero (2); San Lorenzo.
Calling males were found in open scrub forest near Tehuantepec and in savannas near Novillero. The specimens from Tolosita were found under cover in a clearing in the forest (Fugler and Webb, 1957:106).
Specimens from the Pacific lowlands are typical of Gastrophryne usta gadowi Boulenger in possessing a thin line on the posterior surface of the thighs and a thin line from the snout to the vent. Of nine specimens from the Gulf lowlands (Ayentes, Novillero, and San Lorenzo), seven have a middorsal line; this is narrow in four and wide in three. Five have the stripes on the thighs. Two specimens from the middle of the isthmus (Tolosita) have no stripes on the thighs; one has a thin middorsal line, and the other has a broad line. The adult males have a black throat; females have a mottled one. The brown reticulations on the bellies of specimens from the Gulf lowlands is bolder than on specimens from the Pacific lowlands. The presence of certain characters supposedly diagnostic of the subspecies gadowi (line on dorsum and thighs) in the population of usta in southern Veracruz suggests that a redefinition of the ranges of these subspecies will be in order when sufficient material is available to delimit them accurately. For the present I prefer to consider all specimens from the isthmus solely as Gastrophryne usta without referring them to subspecies.
Rana palmipes Spix
Oaxaca: Matías Romero (11); 11 km. S of Santiago Chivela; Santo Domingo; Sarabia. Veracruz: Coatzacoalcos; Cuatotolapam; 25 km. SE of Jesús Carranza (4); Tlacotalpan (2); Tula.