Nanohyla petrigena

N. petrigena was formerly placed in the genus Microhyla, but a 2021 study using morphological and phylogenetic evidence moved nine species (including N. petrigena) to a new genus, Nanohyla.[2][3]

Nanohyla petrigena is a small frog: adult males measure 14–16 mm (0.6–0.6 in) and adult females 15–18 mm (0.6–0.7 in) in snout–vent length.[4] Its hands have only three fingers. The dorsum is colored in shades of brown. There are dark markings on the shoulder and a light band on the flank.The venter is dark with an irregular white blotch.[5]

The male advertisement call is a single, pulsed note, emitted in series consisting of maximally 15 notes. Call repetition rate is about 0.7 per second, declining towards the end of the series.[4]

Nanohyla petrigena occurs in lowland primary rainforests at elevations below 700 m (2,300 ft).[1] It lives in leaf litter. Breeding takes place in small pot-holes on rocky banks of clear streams and rivers and appears to be restricted to certain nights.[1][4] The egg masses float on the surface of these pools.[4] The tadpoles feed in mid-water.[5]

This species appears not to be able to adapt to modified habitats. It is threatened by habitat loss caused by logging and conversion in palm oil plantations; the type locality has already been destroyed and species has likely disappeared from there. However, the species occurs in several protected areas.[1]