Souza L.S., Costa P.M.S

The family Columbellidae is very diverse, with about 900 valid extant species and 74 genera, known from tropical to temperate waters worldwide and from a wide bathymetric range. In Brazil, there are several taxa awaiting to be described. Herein, we studied three new species potentially new to science and provisionally included in Amphissa H. & A. Adams, 1853. The latter genus currently encompasses eight species, three are known from the Atlantic but the genus is probably restricted to cool waters of the northeastern Pacific. The material examined was collected mainly during the cruise MD55 (1987) in Southeast Brazil. We analysed the shells, soft parts and radulae of several specimens. A total of 261 shells (sp. A= 61; sp. B= 100; sp. C= 100) were also measured for a morphometric analysis to aid the discrimination of taxa. Taxonomic identifications were made prior to the measurements to identify each taxon. The following variables were measured: length, width, body whorl length, aperture length and aperture width. The ratio length/width was also calculated. All standardized data was included in a Discriminant Analysis (DA). The three ‘Amphissa’ species could be distinguished from each other and from other similar species mainly by the protoconch morphology, development of teleoconch sculpture, penial morphology and shape of seminal vesicles. The DA also supported the distinction of these three taxa (Wilks’ Lambda= 0.2013631; F12,506= 51.80118) with 87% of the specimens classified correctly. The first axis explains about 96% of the distinction between groups and the most important variables were width and aperture length. The three taxa are known from Southeast Brazil. A further revision of the literature may help us erect a new genus for this particular group of species, since they have consistent differences in relation to the eastern Pacific species of Amphissa.

Acknowledgments: We are grateful to Philippe Bouchet (MNHN, Paris) for granting access to samples collected during the cruise MD55.