Only a narrow connection exists between the posterior, pointed arm of the squamosal and the lateral edge of the proötic. The crista parotica is visible dorsally along the lateral edge of the bony proötic. The squamosal is narrow anteriorly and posteriorly.
The prevomers are short and separated anteriorly by partly ossified cartilage of the overlying solum nasi. The prevomer is joined to the premaxillary by cartilage. The posterior margin of the prevomer articulates directly with the sphenethmoid. The anterolateral and posterolateral processes of the prevomers form the incomplete bony internal margin of the choanae. Each prevomer bears three to six teeth. The palatine is absent. The anterior part of the parasphenoid is narrow and ends in a point. The pterygoid is slender and weakly developed.
Natural History.—Throughout its range Hyla staufferi occurs in subhumid forests and savannas; consequently, the breeding activities are limited by the seasonal occurrence of rainfall, which accumulates in temporary ponds where this species breeds. Clasping pairs and gravid females have been found mostly from June to August throughout its range. This species was observed calling at Finca Taboga, Guanacaste Province, Costa Rica, in mid-July. The males were calling from temporary grassy and weedy ponds in which Hyla microcephala also was calling, but the two species had different calling sites. Hyla staufferi called at stations at heights of five to 80 cm. near the edge of the pond, whereas Hyla microcephala called from emergent vegetation in the middle of the pond. Charles W. Myers informed me that at Penonomé, Coclé, Panamá, he found staufferi calling from grass in puddles where microcephala was absent, and at El Caño, Coclé, Panamá, staufferi was calling from higher sites ("several inches to a few feet above water") than microcephala.
Stuart (1948:34) reported breeding individuals from La Libertad, Guatemala, after rainfall in late May, and Schmidt and Stuart (1941:239) reported staufferi breeding in July in the Salamá basin, Alta Verapaz, Guatemala. Stuart (1935:38) and Duellman (1960:63 and 1963:226) agreed that this species breeds early in the rainy season. However, Rand (1957:519) stated that in El Salvador "these frogs did not begin to call until almost a month and a half after the beginning of the rains." Blair (1960:133) reported that males call in June and July in Chiapas, Oaxaca, Veracruz, and Tamaulipas, México.
The mating call of this species is a series of closely spaced notes having a fundamental frequency of about 100 cycles per second. Each note has a duration of 0.13 to 0.23 second, repeated at intervals that are longer than the duration of the call. The notes are moderately low-pitched and have a dominant frequency of more than 3,000 cycles per second and about 120 pulses per second (Table 2).
Tadpoles.—Measurements of the 33 tadpoles that are available are given in Table 8. The largest tadpole examined is in stage 38 and has a total length of 29.5 mm.
A typical tadpole in stage 38 of development (KU 104162, 5 km ESE Córdoba, Veracruz, México) has a body length of 10 mm., tail length of 19.5 mm., and a total length of 29.5 mm. Other characters are as follows: body as deep as wide, depressed anteriorly; body as long as depth of tail; interorbital space greater than distance between eye and snout but equal to internarial space; nostril equidistant between eye and tip of snout; distance between spiracle and eye less than distance between eye and snout; eyes large, situated dorsolaterally; mouth anteroventral, approximately triangular in outline; one row of papillae covering lower lip and all except median fourth of upper lip; scattered papillae at corners of mouth; tooth rows 2/3; first upper row entire, second row interrupted medially, shorter than first; lower rows shorter than upper rows; beak weak; spiracle short and nearer eyes than anus; anal opening not reaching edge of ventral fin; dorsal fin barely extending onto body; caudal musculature pointed distally.
Table 8.—Sizes of Tadpoles of Hyla s. staufferi in Relation to Developmental Stages.
(Means in parentheses below observed ranges; measurements in mm.)
| Stage | N | Body length | Tail length | Total length |
| 25 | 3 |
6.0-7.0 (6.7) |
12.0-13.0 (12.5) |
18.0-20.0 (19.2) |
| 26 | 2 |
7.0-7.5 (7.3) |
14.0-15.0 (14.5) |
21.5-22.0 (21.8) |
| 27 | 9 |
7.0-8.0 (7.6) |
13.0-17.0 (14.5) |
21.0-25.0 (22.0) |
| 32 | 1 | 8.5 | 15.5 | 24.0 |
| 36 | 2 |
8.0-10.0 (9.0) |
16.5-17.0 (16.8) |
25.0-26.5 (25.8) |
| 38 | 6 |
9.0-10.0 (9.6) |
19.0-20.5 (19.5) |
28.0-29.5 (29.1) |
| 41 | 1 | 10.0 | 14.0 | 24.0 |
| 42 | 6 |
11.0-14.0 (11.8) |
10.0-13.0 (11.9) |
20.0-29.0 (24.8) |
| 45 | 1 | 12.5 | 0.5 | 13.0 |
| 46 | 1 | 13.0 | — | — |
In life, body pale olive-tan, belly silvery white with pinkish-orange reticulations in some specimens; tail creamy white with silvery flecks and black or brown reticulations. In preservative, tan and pinkish-orange coloration lost; body transparent, reticulations on tail present.