LAUSR

Crete with its complex geomorphological history is the island with the highest number of endemism observed in animal and plant taxa throughout the Aegean archipelago. While other groups of organisms within Crete are well-studied, the freshwater gastropod fauna still remains poorly investigated. Bythinella and Pseudamnicola, are two genera of freshwater springsnails, both present on the island, inhabiting springs and other freshwater habitats. Here, we conduct a comprehensive study on the distribution of the different genetic lineages of the two gastropod genera in order to assess the mode of their differentiation on the island and infer the actual number of species present in the island. Towards these aims, sequence data from the mitochondrial gene (COI) were used and analyzed within a phylogenetic framework. For Bythinella, our results strongly support five at least delineated Bythinella spp. inhabiting Crete, which correspond to the already described species from previous studies with the addition of a new one. Bythinella analyses reveal an old time-frame of differentiation with vicariant phenomena being more likely the main drivers shaping the present-day distribution of the genus' genetic lineages. For Pseudamnicola, our data indicate the presence of at least two delineated Pseudamnicola spp. with a differentiation more consistent to an isolation-by-distance pattern of a relatively recent origin. Dispersion processes followed by isolation of the populations and/or recent speciation, seem to be the underlying process for the current distribution of Pseudamnicola lineages. This article is protected by copyright. All rights reserved.