Field studies on hylid frogs in southern México and northern Central America have resulted in the collection of numerous specimens of _Ptychohyla_, a genus of hylid frogs heretofore poorly represented in museum collections. Experience with the living frogs in their natural habitats has been helpful in defining the species and in formulating ideas concerning their relationships.

Taylor (1944) proposed the generic name _Ptychohyla_ for a new species of frog, _Ptychohyla adipoventris_ [= _Ptychohyla leonhard-schultzei_ (Ahl)–_fide_ Duellman, 1960] from Agua del Obispo, Guerrero. Taylor defined the genus as having large ventrolateral glands and horny nuptial spines in males. Stuart (1954:169) discussed the generic characters and pointed out that both the ventrolateral glands and horny nuptial spines were seasonal in their development, being found only in breeding males. Stuart then went on to describe _Ptychohyla schmidtorum_, a species characterized by the absence of horny nuptial spines in breeding males.

My investigations of these frogs have revealed the presence of two groups of species. In both groups breeding males have large ventrolateral glands, but the two groups are easily separated by four characters. The first group contains, among others, _Ptychohyla leonhard-schultzei_, _euthysanota_, _spinipollex_, and another species in the Mesa Central of Chiapas to which I tentatively apply the name _Ptychohyla macrotympanum_ (Tanner), 1957. This group of species is characterized by horny nuptial spines in breeding males, presence of a tarsal fold, a call consisting of a single long note, and tadpoles having lips not greatly expanded. The second group, as recognized here, is characterized by the absence of horny nuptial spines in breeding males, lack of a tarsal fold, a call consisting of a series of short notes, and tadpoles having greatly expanded lips. In this group belong _Ptychohyla schmidtorum_ and the two species described below.