Litthabitella chilodia (Westerlund, 1886) in Italy (Gastropoda : Prosobranchia : Hydrobiidae)

Abstract

Bythinella opaca pollinensis Bacci (1952) is herein regarded as a junior synonym of Litthabitella chilodia (Westerlund, 1886). Litthabitella Boeters, 1970, is a genus of hydrobiid prosobranchs characterized by: penis apex bifid, divided into apical lobe and tip of penis proper; one–four irregularly shaped glandular swellings on ventral side of apical lobe and penis close to base of lobe; well developed bursa copulatrix; two seminal receptacles, proximal (RS2) smaller than distal (RS1). At present it includes only the type species L. chilodia present in the western Balkans, Ionian islands and southern Italy. Paludinella elliptica Paladilhe, 1874, from the Pyrenees, once attributed to Litthabitella, still has uncertain taxonomic relationships. The current subdivision of L. chilodia into L. chilodia chilodia and L. chilodia ionica (Schutt, 1980) is rejected. Examination of the type material of the latter from the island of Corfu, showed that it includes two different taxa, one of which (the holotype) is a species of Belgrandia and the other L. chilodia. Due to the absence of anatomical data, the taxonomic status of Belgrandia ionica (Schutt, 1980) is still uncertain. Italian populations of L. chilodia are characterized by wide variation in shell shape and size and one population, living in a small brook in the cave Grotta del Tasso in Apulia, has two distinct coexisting shell morphs, almost without intermediates.