A new record of Nerita nigrita Röding, 1798 (Mollusca: Gastropoda: Neritidae) from India

Abstract

Many members of the family Neritidae display polymorphism as their shells can be highly variable in colour, which has sometimes led to confusion in the identification of closely related species. One such confusion in the taxonomic identification of two Nerita spp. currently exists in India. According to the literature and identification keys available, Nerita nigrita does not exist in the country (has not been reported), but the reason is that this species has thus far been misidentified as Nerita maxima. The key difference between these two species can be observed in their shell spire - N. nigrita consists a slightly elevated spire with distinguishable protoconch, whereas N. maxima has a depressed spire with indistinct protoconch. Other identification characters which separate these two species, such as shell texture, operculum structure and outer lips are also described. The present study reports N. nigrita as a new record from the Indian coast.