Somatina purpurascens is a moth of the family Geometridae first described by Frederic Moore in 1887.

The tibia is dilated with a fold and large tuft of long hair.

There is a sub-marginal waved line produced to a point below costa, then usually obsolescent, the area beyond it rufous as far as the marginal rufous band of triangular marks, which does not extend to the costa.

Hindwings with cell-speck and traces of waved medial and postmedial line.

The outer area fuscous, with marginal series of triangular rufous marks.