Abnormal sinistrorsity in the Marginellidae (Gastropoda)

Two species of Marginellidae, Closia angustata (Sowerby, 1846) and Hyalina effulgens (Reeve, 1865), are added to Dance’s list (1972) of abnormal sinistral marine gastropods. Including four other records the total number has increased to 70 species. Of these, 29 belong to the Marginellidae, which occur in all tropical and subtropical seas. There is no explanation so far for this very high percentage of sinistral species in a single family. Abnormal sinistrorsity seems to be related to the evolution of the Gastropoda: sinistral specimens are unknown in the primitive order of the Archaeogastropoda, they are rare in the Mesogastropoda (8 species), and less rare in the Neogastropoda (62 species). Within the order of the Neogastropoda, the superfamily Volutacea has the most (43) sinistral species, of which the major part (29 species) belongs to the family Marginellidae.