Variation.—The third upper tooth-row is interrupted in all specimens, but in some individuals the first upper row and first lower row are complete. The only noted variation in color is the intensity of brown pigmentation on the caudal musculature, which in most specimens is sufficiently dense to make the tail look brown. In some specimens the mid-lateral streak is indistinct, and the pale spot below the streak is absent.

Comparisons.—Aside from the characters listed in the diagnosis, Ptychohyla schmidtorum chamulae differs from P. schmidtorum schmidtorum by having dark brown webbing on the feet, instead of pale creamy tan webbing, and in having in life a yellow venter, instead of a white venter. Ptychohyla ignicolor also is green in life, but has red flash-colors on the thighs, red webbing on the feet, and lacks the white lateral stripe diagnostic of P. schmidtorum chamulae.

Plectrohyla matudai matudai and P. guatemalensis are sympatric with Ptychohyla schmidtorum chamulae. Each of the first two has a bony prepollex, rugose skin on the dorsum, and heavy body. Also living with Ptychohyla chamulae are Hyla chaneque, a large species having a tuberculate dorsum and webbed fingers, and Hyla bivocata, a small yellow species having a broad, flat head, small indistinct tympanum, and an axillary membrane.

Life History.—Calling males were found on leaves of herbs and bushes by cascading streams in cloud forest. The call consists of series of short notes, three to nine notes per series, sounding like "raa-raa-raa." The duration of each note is .054 to .070 of a second, and has a rate of 96 to 110 pulses per second. The dominant frequency falls between 3350 and 3450 cycles per second ([Pl. 11D]). The call is almost indistinguishable from that of Ptychohyla schmidtorum schmidtorum.

Tadpoles were found in the cascading streams; the smallest tadpole has a total length of 17.2 mm. and has only 3⁄2 tooth-rows. At a stream 6.2 kilometers south of Rayón Mescalapa, Chiapas, metamorphosing young were found on June 16 and August 5, 1960. Each of two completely metamorphosed young has a snout-vent length of 15.7 mm. Another having a snout-vent length of 16.2 mm. has a tail stub 2 mm. long and a completely metamorphosed mouth. Two others have snout-vent lengths of 13.6 and 14.1 mm. and tail lengths of 11.5 and 8.1 mm. respectively; in these the mouth parts are incompletely metamorphosed.

Remarks.—Duellman (1961:354) described Ptychohyla chamulae and stated that it probably was most closely related to P. schmidtorum. Further study has revealed additional resemblance in morphological and behavioral details. It is concluded that the two populations are more realistically treated as subspecies than as species. The geographic ranges, as now known, are disjunct. Ptychohyla schmidtorum chamulae inhabits cloud forest on the Atlantic slopes of the Chiapan Highlands, whereas P. s. schmidtorum lives in cloud forest on the Pacific slopes of the Sierra Madre in Chiapas and Guatemala. Between their known geographic ranges are the pine clad Sierra Madre and Chiapan Highlands, and intervening sub-humid Grijalva Valley.

Distribution.—This species is known only from elevations between 1500 and 1700 meters on the Atlantic slopes of the Chiapan Highlands; it is to be expected in cloud forests on the northern slopes of the Sierra de Cuchumatanes in Guatemala.

Specimens examined.—Mexico: Chiapas: 15 km. N of Pueblo Nuevo Solistahuacán, UMMZ 123325 (4); 16.5 km. N of Pueblo Nuevo Solistahuacán, UMMZ 123322 (10); 18 km. N of Pueblo Nuevo Solistahuacán, UMMZ 121395-9, 123324 (8), 123326 (5); 18.6 km. N of Pueblo Nuevo Solistahuacán, UMMZ 123323 (4); 5.6 km. S of Rayón Mescalapa, KU 58062, 58200 (tadpoles); 6.2 km. S of Rayón Mescalapa, KU 58063-74, 58199 (tadpole), 58234-8, 59936 (skeleton).

Plate 18

Click to View Larger. 		Ptychohyla ignicolor Duellman
Ptychohyla ignicolor Duellman, Uni. Kansas Publ. Mus. Nat. Hist., 13:352-353, pl. 25, fig. 1, April 27, 1961 [Holotype.—UMMZ 119603 from 6 kilometers south of Vista Hermosa, Oaxaca, México; Thomas E. Moore collector].