The status of two vermetid species is reassessed after examining the type of Vermetus roussaei Vaillant, 1871 from the malacological collection of the Muséum national d’Histoire naturelle, Paris. Vermetus roussaei is referred to genus Petaloconchus Lea, 1843, subgenus Macrophragma Carpenter, 1857, on the basis of shell morphology. Records of this species from the Philippines and the Indian Ocean actually refer to a new species, Vermetus (Thylaeodus) enderi n. sp., which shares with the previous taxon only the external appearance. This new species is commonly found on the axial branches of reophylic anthozoans, as black corals (Antipathes spp.) or gorgonaceans.
Indian Ocean, ecology, Vermetidae, taxonomy, new species.