The distribution of species of _Ptychohyla_ reflects the distribution
of cloud forest in southern Mexico 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.
[Illustration: 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 Leon, _Hyla miotympanum_ seems to be the ecological
replacement of _Ptychohyla_. On the Pacific slopes north of Guerrero,
Mexico, 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 Panama,
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_.