The genus Megastomia Monterosato, 1884 includes five known species in the Mediterranean Sea. However, examination of several specimens from eastern Mediterranean revealed the presence of a further species, which is here described as Megastomia crovatoi n. sp. In order to ascertain whether this species is native, we examined several samplings from both the Red Sea and other Indo-West Pacific localities and carried out a detailed survey of the literature dealing with Indo-West Pacific odostomiins. As a result, we have to conclude that, to the best of our knowledge, the new species is native to the Mediterranean Sea. We compare the new species with the other congeners occurring in the Mediterranean Sea and illustrate the type material of four similar species described in 1924 by Hornung & Mermod from Eritrea, originally placed in the genus Syrnola, i.e., Megastomia bedoti, M. broti, M. gestroi and M. lorioli.