Richardsonichthys, is a monotypic genus of marine ray-finned fish belonging to the subfamily Tetraroginae, the waspfishes, which is classified as part of the family Scorpaenidae, the scorpionfishes and their relatives.

[3] A. leucogaster had been described in 1848 by the Scottish naval surgeon, Arctic explorer and naturalist John Richardson with its type locality given as the "Sea of China".

The specific name, leucogaster, means "white-bellied", an allusion to the white ventral surface of this species.

[6] Richardsonichthys leucogaster has an oblong body, which does not show strong lateral compression, with a rounded dorsal profile of the head.

The colour is very variable but lower body, the pectoral, pelvic, anal and caudal fins are typically reddish.