It is endemic to the Central African Republic and is only known from its type locality, Bouala (originally spelled "Buala"), at 998 m (3,274 ft) above sea level on the Ouham River.

[2][4] This name presumably reflects the earlier assumption that the type locality was in Chad, into which the Ouham River flows.

[4] Phrynobatrachus pygmaeus was described by German zoologist Ernst Ahl in 1925 based a single specimen, the holotype.

[3] Phrynobatrachus pygmaeus is the type species of the genus Micrarthroleptis erected in 1938 by Kurt Deckert [de].

Dorsal skin is warty and has two X-shaped ridges in the scapular region.