Salles A.C.A., Oliveira C.D.C., Pimenta A.D

Mollusca phylum is the second most diverse in terms of described species, and it also has the highest documented extinction rate. With the degradation of the environment and the increase in global temperature, terrestrial gastropods are strongly affected, corresponding to about 45% of endemic mollusks in Brazil at risk of extinction. Undoubtedly, this is underestimated by the lack of environmental policies and the demoralization of conservation, a path that Brazil has followed in recent years. The Brazilian Atlantic Rainforest is a biodiversity hotspot and houses more than 8000 endemic plants and faunal species. Unfortunately, its current coverage corresponds to 12.4% of what was originally occupied, with that, many species were extinct even before they were known. There are 19 species of the genus Rhinus occurring in Brazilian Atlantic rainforest, only two described based on conchology and anatomical characters. For almost all the remaining species, the literature available is limited to faunal surveys and catalogs, and any descriptive studies are restricted to original descriptions based only on shell. In this work we redescribe 5 species of Rhinus based on anatomical and shell morphology and we present the first description of spermatophores for the genus. Specimens of Rhinus ciliatus, R. durus, R. evelinae, R. heterotrichus and R. suturalis were dissected and pallial cavity and digestive, reproductive and nervous systems were examined in stereoscopic microscope. Details of shell, radula, jaw and when present, spermatophores, were achieved by scanning microscopy. Significant differences were observed in relation to: kidney shape, peripheral glands, connectives between salivary gland ducts, extension of flagellum, position of copulatrix bursa, degree of fusion between ganglia, among other characteristics. We hope this work contributes to a greater knowledge of species of Rhinus that occur in Brazilian Atlantic Rainforest by presenting hitherto neglected anatomical details, considering this the first step towards its preservation.

Acknowledgments: UFRJ, MZUSP, ICMBio and CNPq for financing resources.