Variation.—The paratypes are smaller, having snout-vent lengths of 48.3 and 41.8 mm. In these specimens the ratio of the length of the tibia to the snout-vent length is 55.9 and 57.9 per cent, and the ratio of the diameter of the tympanum to the diameter of the eye is 47.3 and 43.6 per cent, respectively. Both specimens have 4-4 prevomerine teeth; one specimen has 37-36, and the other has 40-37, maxillary-premaxillary teeth. In these small specimens the supratympanic fold is thin, and the arms are not so robust as in the holotype. In one specimen (KU 58873) the tongue is not notched posteriorly. The terminal subarticular tubercle on each fourth finger is broad and flattened in UIMNH 40837, but conical in KU 58873. Both specimens have bold creamy-yellow and dark brown mottling on the flanks and dark brown reticulations on the ventral surfaces of the shanks. There are two dark brown vertical bars on the anterior and posterior surfaces of each thigh in KU 58873 and three bars on each surface in UIMNH 40837.
Comparisons.—Plectrohyla hartwegi differs from all known species in the genus by having boldly mottled flanks, dark reticulations on the ventral surfaces of the shanks, and dark vertical bars on the shanks. In all of the other species the anterior and posterior surfaces of the thighs are unmarked, and the flanks are either plain or marked with small spots or flecks. Structurally, P. hartwegi belongs in the guatemalensis group of the genus, containing avia, glandulosa, guatemalensis, and pycnochila. The species in this group lack vocal slits and have either large, rectangular, or bifid prepollices. Plectrohyla hartwegi differs from all of these species, except pycnochila, by having a tuberculate, instead of a smooth, dorsum, and hartwegi differs from pycnochila by having a bifid, instead of a rectangular, prepollex.
Remarks.—The known distribution of Plectrohyla hartwegi includes three localities at elevations of 1000 to 2050 meters in the Sierra Madre of Chiapas and extreme eastern Oaxaca. The specimen from Parajé El Triunfo was found in a rocky stream in cloud forest at an elevation of 2050 meters. One Plectrohyla sagorum was obtained from the same stream.
Eizi Matuda sent the holotype to the late Dr. Norman Hartweg, who recognized that the specimen was unique but was reluctant to name the species on the basis of a single specimen. Now that two additional specimens are available, it seems appropriate to associate Hartweg's name with this new species of Plectrohyla, a genus that Hartweg first adequately defined.
LITERATURE CITED
Adler, K.
| 1965. | Three new frogs of the genus Hyla from the Sierra Madre del Sur of México. Occas. Papers Mus. Zool. Univ. Michigan, 642:1-18, pl. 1, December 16. |
Duellman, W. E.
| 1960. | Synonymy, variation, and distribution of Ptychohyla leonhardschultzei Ahl. Studies of American hylid frogs, IV. Herpetologica, 16:191-197, September 23. |
| 1964. | A review of the frogs of the Hyla bistincta group. Univ. Kansas Publ. Mus. Nat. Hist., 15:469-491, March 2. |
| 1965. | Frogs of the Hyla taeniopus group. Copeia, 2:159-168, June 25. |
Starrett, P.