The distribution of species of Ptychohyla reflects the distribution of cloud forest in southern México and northern Central America. The frogs are restricted to mountainous areas, usually at elevations higher than 1000 meters above sea level. Ptychohyla does not range to great heights in the mountains, where west of the Isthmus of Tehuantepec the mountain streams are inhabited by frogs of the Hyla bistincta group, and in Chiapas and Guatemala by species of Plectrohyla.
Frogs of the Ptychohyla euthysanota group have a greater combined geographic range than the species comprising the Ptychohyla schmidtorum group (Fig. 7). No two species in the same group are sympatric, but members of different groups are sympatric in at least parts of their ranges. Apparently P. leonhardschultzei ranges around the southern edge of the Mexican Highlands, where the species occurs on both Atlantic and Pacific slopes; as can be seen from the distribution map, there are many gaps in the known range of this species. The range of P. euthysanota euthysanota is along the Pacific slopes of the Sierra Madre in Chiapas, Guatemala, and El Salvador, whereas that of P. euthysanota macrotympanum is along the southern interior slopes of the Central Highlands of Chiapas and the Sierra de Cuchumatanes in Guatemala. Ptychohyla spinipollex occurs on the wet Atlantic slopes of the Guatemalan and Honduranean Highlands; the range of the species in Honduras is poorly known.
Fig. 7. Map showing locality records for the species and subspecies of Ptychohyla.
The frogs of the Ptychohyla schmidtorum group have more restricted geographic ranges than members of the former group. Ptychohyla schmidtorum schmidtorum occurs on the Pacific slopes of the Sierra Madre in Chiapas and Guatemala, where it occurs with P. euthysanota euthysanota; P. schmidtorum chamulae is known from only two localities on the Atlantic slopes of the Central Highlands of Chiapas, where it occurs close to, but as now known not with, P. euthysanota macrotympanum. On the Atlantic slopes of the Sierra Madre Oriental in northern Oaxaca P. ignicolor occurs with P. leonhardschultzei.
In the Sierra de los Tuxtlas in southern Veracruz and in the cloud forests along the eastern slopes of the Sierra Madre Oriental northward to Nuevo León, Hyla miotympanum seems to be the ecological replacement of Ptychohyla. On the Pacific slopes north of Guerrero, México, humid forests in which there are cascading mountain streams are absent; consequently, no Ptychohyla are known from that region. In the mountains of El Salvador Ptychohyla euthysanota euthysanota occurs sympatrically with another small stream-breeding hylid, Hyla salvadorensis. To the south of Honduras the highlands diminish into the lowlands of Nicaragua, where habitat suitable for Ptychohyla apparently does not exist. In the mountains of Costa Rica and Panamá, the habitats occupied by Ptychohyla in northern Central America are filled by a variety of stream-breeding Hyla, such as Hyla legleri, H. rivularis, H. rufioculis, H. alleei, and H. uranochroa.
Although members of the genus Ptychohyla occur in the southern part of the Mexican Highlands to the west of the Isthmus of Tehuantepec, the greater distribution and differentiation in the genus is in the Chiapan-Guatemalan Highlands. In this respect Ptychohyla is a counterpart of Plectrohyla.
Habitat Preference