Biometric and Genetic Analysis of the Marine Rissoid Rissoa auriscalpium (Gastropoda, Prosobranchia) and its Ecological Implications

Abstract

Abstract. Two forms of Rissoa auriscalpium were found in Posidonia oceanica beds around the Island of Ischia (Gulf of Naples). In order to investigate their taxonomical value and to quantify the discriminating features found, the radular, conchometric, genetic, and ecological features of the two forms were analyzed. Ecological observations showed that the distribution of the two forms is strongly correlated with hydrodynamic factors.