Enteropsis fusiformis, new species, is described on the basis of females living in the compound ascidian Polyclinum ?insulsum Sluiter, 1897 from Madagascar. Main characteristic features for the new species are given with respect to body shape (fusiform, with cone-shaped urosome), anus (longitudinal slit, displaced to posterior dorsal metasome), antennule (elongated), antenna (second segment a sharply pointed long process), labrum (with 2 triangular and 4 slender submerginal setae), and maxillule (palp digitiform). The subconical terminal portion of the cone-shaped urosome is formed by the completely fused caudal rami. The new species is the only representative of the subfamily Enteropsinae (Ascidicolidae) in the Humes collection from Madagascar.