Colostethus agilis Lynch & Ruiz-Carranza 1985

Colostethus agilis is a small frog but moderately sized for a Colostethus, attaining a SVL averaging 24 mm for males and 28 mm for females. Males have a dilated third digit. The head is wider than it is long but not as wide as the body. Snout truncated in dorsal view and projects beyond the anterior extremity of the upper labial. Nostrils are directed laterally. The ventral portion of tympanum is visible while the dorsal portion is covered by the supratympanic fold. Dorsal and gular skin is smooth. Males have vocal slits positioned posterolaterally to the tongue. Ulnar tubercles absent. Discs on toes are round and smaller than those on the hands. When adpressed anteriorly, the ankle reaches a point near the anterior portion of the orbit. Colostethus agilis is also characterized by a a dorso-and-ventrolateral row of warts/bumps and a row of blotches laterally. In life, this Colostethus is characterized by the presence of olive dorsal coloration with brown blotches or brown dorsal coloration with black blotches. The upper lip has white spots. Thighs and inguinal region have pale whitish-yellow blotches. Iris is brown with golden specks. Few members of the genus Colostethus have much more than basal interdigital webbing on the hind feet. Even rarer are those which have extensive, almost complete, interdigital webbing. At the time of its description, Colostethus agilis was one of only five Colostethus with such extensive webbing (the other four species were: C. chocoensis, C. fuliginosus, C. palmatus, and C. vergeli) (Lynch and Ruiz-Carranza 1985).

Colostethus agilis is known from the western Cordillera Occidental of Colombia (Departamentos del Cauca y Valle) at elevations between 2190 and 2600 m.

Individuals were found active during the day and not active at night. Adults were found at the edge of breaks in the cloud forests, where adults and juveniles were very common.