A gravel beach shelled micro-gastropod assemblage from Ceuta, Strait of Gibraltar, with the description of a new truncatelloidean genus

Abstract

An interstitial shelled gastropod assemblage from an intertidal gravel beach at Ceuta, southern Strait of Gibraltar, is described. Apart from a juvenile trochid (Gibbula racketti), the fauna of minute gastropods is dominated by six species forming three morphologically similar species pairs. There are two species of Skeneidae and Caecidae, together with two species previously included in the rissoid genus Peringiella. Each species pair is convergent in shell morphology, the Peringiella-like species are shown to belong in different families. One, P. elegans, is a rissoid but the other, P. epidaurica, is shown to be a new genus, BOTRYPHALLUS, which is provisionally included in the Hydrobiidae (Littoridininae). The vertical distribution of this fauna on the beach is briefly described. [Other species discussed are Skenea serpuloides, Dikoleps pruinosa, Caecum incomptum, C. clarkii and Botryphallus epidauricus].