Sarcohyla psarosema (Campbell & Duellman 2000)

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.

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.

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).

Sarcohyla psarosema is a species of frogs in the family Hylidae.

It is endemic to the Sierra Madre de Oaxaca of Mexico. Its natural habitats are subtropical or tropical moist montane forests and rivers. It is threatened by habitat loss.