Abstract
The tree-frog family Hylidae is represented in Costa Rica by 39 species placed in five genera. Anotheca and Phrynohyas are represented by a single form; Hyla by 26 species ; Phyllomedusa by six species; and Smilisca by five species. Within the latter three genera the species may be grouped by similarities as follows: Hyla - Miliaria group; fimbrimembrana, immensa and richardtaylori; Faber group: rosenbergi; Albomarginata group: rufitela; Leucophyllata group: ebraccata, loquax, microcephala and phlebodes; Rubra group: boulengeri, elaeochroa and staufferi; Uranochroa group; debilis, pictipes, rivularis, tica, legleri, Iythrodes, rufioculis and uranochroa; Zeteki group: picado; and zeteki; unassigned to group: angustilineata, colymba, lancasteri and pseudopuma; Phyllomedusa - Callidryas group: annae, calcarifer, callidryas, saltator and spurrelli; Lemur group: lemur; Smilisca - Baudinii group: baudinii and phaeota; Sordida group: sila, sordida and puma.
Brief synonymies, diagnoses and a summary of distinguishing character istics are given for all species except the Phyllomedusa. The following names are placed in synonymy: Hyla cherrei Cope, H. microcephala Boulenger and H. underwoodi Boulenger (= H. microcephala Cope); Hyla spilomma Cope and Acrodytes modesta Taylor & H. M. Smith (= Phrynohyas venulosa Laurenti).
Twelve of the 39 species are known only from Costa Rica. Within Costa Rica four majar geographic distribution patterns are found. Seven species are wide-ranging lowland form found on both Atlantic and Pacific coasts ; six are restricted to the Atlantic lowlands; 20 are found only in the cordilleras.
On an altitudinal basis 21 species occur in the Tropical Lowlands 19 species in the Subtropical zone, 5 are Lower Montane forms and only 2 are found above 2 500 m in the Montane zone. 12 species are restricted to the Tropical Lowlands, 13 to the Subtropical zone and one to the Lower Montane. 10 species ocrur in both Tropical and Subtropical zones, two in Sub tropical and Lower Montane and two in Lower Montane and Montane zones.
The breeding site of each species serves as one mcasure of its ecologic niche. Fifteen forms breed in ponds or marshes, 12 are stream breeders, six lay eggs out of water on lea ves of bushes or trees and three deposit the eggs in water trapped in epiphytic bromeliads. The known sympatric ocrurrence of Costa Rican hylids is summarized.
A summary of diagnostic characteristics and a key to Costa Rican hylids in English and Spanish is provided to aid in field identification.