| Species | N | Snout-vent length | Tibia length Snout-vent length | Head width Snout-vent length | Tympanum Eye |
|---|---|---|---|---|---|
| H. bistincta | 38 | 43.0-53.8 (46.3) | 0.47-0.52 (0.49) | 0.32-0.37 (0.34) | 0.35-0.48 (0.42) |
| H. charadricola | 10 | 35.3-44.4 (40.4) | 0.50-0.54 (0.52) | 0.31-0.33 (0.32) | 0.30-0.37 (0.34) |
| H. robertsorum | 26 | 39.9-47.9 (43.1) | 0.48-0.51 (0.49) | 0.30-0.36 (0.32) | 0.36-0.47 (0.41) |
| H. pachyderma | 1 | 39.9 | 0.53 | 0.32 | ... |
| H. crassa | 1 | 53.7 | 0.50 | 0.33 | 0.28 |
Frogs in this group are rather drab in appearance. The dorsal color varies from dull green to various shades of brown. The most distinct aspect of the coloration is the different color patterns on the flanks and posterior surfaces of the thighs. The flanks in all species are marked with spots or reticulations.
Hyla bistincta differs from other members of the group in having vocal slits and a distensible vocal sac. Only this species has been reported to call (Shannon, 1951:473). Insofar as is known, the other species are mute. Examination of skeletal preparations of H. bistincta, charadricola, and robertsorum and X-rays of the other species shows no notable specific differences in the osteology. Since the tadpoles of only H. bistincta (Duellman, 1961:47) and H. robertsorum (Rabb and Mosimann, 1955) are known, larval characters are of limited use in intra-group systematics.
Key to the Species of the Hyla bistincta Group
1. Snout, in dorsal profile, short and bluntly rounded; canthus rounded, sometimes indistinct, vocal slits absent 2
Snout, in dorsal profile, longer, squared; canthus distinct, vocal slits present or absent 4
2. Feet webbed to base of discs; dorsum dull olive green; flanks having cream-colored spots [H. crassa], p. 486
Feet not webbed to base of discs; dorsum brown 3
3. Tarsal fold strong; thoracic fold heavy; webbing on feet extending to middle of penultimate phalanx of fourth toe; distinct white stripe above anus; cluster of largo spines on thumb in breeding males, [H. pachyderma], p. 485
Tarsal fold weak and short; thoracic fold absent or barely indicated; webbing of feet extending to base of penultimate phalanx of fourth toe; no distinct white stripe above anus; nuptial tuberosities in breeding males consisting of small spines [H. robertsorum], p. 481
4. Tarsal fold strong; anal flap elongate; anus opening at lower edge of femur; dorsum tan or brown; flanks mottled with cream and brown; venter immaculate creamy white; no anal stripe; vocal slits present, [H. bistincta], p. 475
Tarsal fold faint and short; anal flap not elongate; anus opening at middle of femur; dorsum olive-green with black reticulations; flanks greenish gray with brown or black spots; a row of white flecks above and below anus, vocal slits absent [H. charadricola], p. 478