Description
Member of the Hyla bistincta group sensu Duellman (1970) and Duellman and Campbell (1992). This species has a dark brown dorsal ground color with white flecks and reticulations on the trunk and exposed surfaces of the limbs. The markings become larger and higher in density on the flanks and limbs than on the trunk of the body. Irregular bright green spots occur on top and sides of head, few occur on dorsal surfaces of limbs and flanks. Tympanum not visible externally. Nuptial pads in breeding males are composed of minute spines covering the entire prepollex. Males lack vocal slits. The smallest member of the H. bistincta group where males reach a maximum SVL of 31.4 mm and females 37.3 mm. Skin on dorsum is thick. Thoracic fold and the quadratojugal are absent. In the holotype (adult male), head as wide as body but slightly longer than wide. Head width 31.1% SVL, head length 32.8% SVL. Snout short and rounded in dorsal view but truncated in lateral view. Nostrils protuberant and projected anterolaterally. Supratympanic fold not well developed. Forearms hypertrophied in males. Fingers with only a trace of webbing, whereas toes are about two thirds webbed. When hindlimbs adpressed anteriorly, heels overlap by 25% length of shank. Cloacal opening directed ventrally at midlevel of thighs.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Mexico

View distribution map in BerkeleyMapper.

This species is known from the type locality at 2103 m in cloud forests. Three males were found in crevices between large boulders in splash zones of waterfalls on a small stream that is a tributary of Rio La Lana. A male and female were found on leaves of vegetation along the same stream. All specimens were found late at night.

Life History, Abundance, Activity, and Special Behaviors
From the sample size of males, variation was found to occur in the number and color/shape of nuptial spines on prepollex. This is most likely due to the difference in breeding phase of individual males (some nuptial pads were developing while others were regressing).

References

Duellman, W. E., Campbell, J.A. (1992). ''Hylid frogs of the genus Plectrohyla: systematics and phylogenetic relationships.'' Miscellaneous Publications, Museum of Zoology, University of Michigan, 181, 1-32.

Duellman, W.E. (1970). The Hylid Frogs of Middle America. Monograph of the Museum of Natural History, University of Kansas.

Species Account Citation: AmphibiaWeb 2008 Sarcohyla psarosema <https://amphibiaweb.org/species/6121> University of California, Berkeley, CA, USA. Accessed Feb 3, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 3 Feb 2025.

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