PLATE 1
Living Hyla: (A) H. boulengeri (KU 86322) and (B) H. foliamorta (KU 101576), × 2.
PLATE 2
Living Hyla: (A) H. elaeochroa (KU 91688), (B) H. staufferi staufferi (KU 57791), and (C) H. staufferi altae (KU 101688), × 2.
PLATE 3
Audiospectrograms and sections of mating calls of (A) Hyla boulengeri (KU Tape No. 511) and (B) H. foliamorta (KU Tape No. 288).
PLATE 4
Audiospectrograms and sections of mating calls of (A) Hyla elaeochroa (KU Tape No. 97), (B) H. s. staufferi (KU Tape No. 93), and (C) H. staufferi altae (KU Tape No. 502).
The prevomer is short, and broadest anteriorly. The prevomer is joined to the premaxillary by ossification. The posterior margin of the prevomer bears a narrow cartilaginous articulation with the sphenethmoid. The anterolateral and posterolateral processes of the prevomer form an incomplete bony margin to the small choanae; each prevomer bears four to seven teeth. The palatine is small, curved anteriorly and edentate. The anterior part of the parasphenoid is robust and ends in a point. The pterygoid is slender and weakly developed.
Natural History.—Hyla elaeochroa inhabits humid lowland tropical forests in lower Central America and breeds in temporary ponds. Clasping pairs, gravid females, and calling males have been found mostly in June, July, and August. William E. Duellman informed me that he also found males calling in mid-February, late April, and May. Duellman (1967) reported detailed observations of the social organization in the mating call of Hyla elaeochroa. The choruses in this species are initially organized, but when many individuals call, the chorus loses organization. I observed this species breeding in a temporary pond at Puerto Viejo, Heredia Province, Cost Rica, in late June. Calling males and clasping pairs were extremely abundant within a few hours after a heavy rain. Males were mostly found calling from low emergent herbs in the pond and less commonly from bushes and trees to heights of six meters above the water. Calling males were also observed at Ricón de Osa, Puntarenas Province, Costa Rica, in late July. These breeding individuals were found in a shallow pond at the edge of a wet forest. Calling stations were less than two meters in height. John D. Lynch informed me that after a heavy rain in early August, he found several hundred individuals congregated in a small grassy pond less than a foot deep, at Rincón de Osa. Males were calling from sites on grass stems a few centimeters above the water.