The ibero-balearic region: one of the areas of highest Hydrobiidae (Gastropoda, Prosobranchia, Rissooidea) diversity in Europe

Abstract

The prosobranch mollusc family Hydrobiidae Troschel, 1857 has a cosmopolitan distribution and is made up of small to minute species that inhabit permanent aquatic ecosystems. It is one of the largest families within the superfamily Rissooidea. The evolutionary relationships between members of this family are still unclear due to: 1) insufficient available information regarding the morphological characters of many of the described taxa, 2) uncertainty concerning which morphological characters are of greatest taxonomic and phylogenetic interest, and 3) the rare use of molecular characters to study evolutionary relationships. In this work, we examine the reasons for the confusing systematics of hydrobiids. We include a diagnosis of the 13 genera and a list of the 43 species described and accepted to date for the Ibero-balearic region, along with data regarding their geographic distribution and a compilation of the most relevant bibliographical references. The Iberian Peninsula is one of the areas of greatest hydrobiid diversity in Europe, and has a large number of endemic genera and species in addition to those that have a typically circummediterranean distribution. Numerous hydrobiid species and populations are threatened, and in some cases, in danger of extinction due to the fragile nature of many of the ecosystems they inhabit.