New data on Hydrobiidae systematics: two new genera from the Iberian Peninsula

Abstract

A deep systematic study of the Spanish hydrobiid fauna is unravelling a more complex group of species than was previously described. The use of different taxonomical and statistical methodologies helps to clarify this old classification. Based on anatomical studies made for the first time on specimens from the type locality of Paludina sturmi (Rosenhauer, 1856), the species is redescribed and transferred to a new genus Boetersiella. The study demonstrates that Horatia (?) sturmi (sensu Boeters, 1988) is a combination of two species belonging to two new, different but closely related genera, B. sturmi and Chondrobasis levantina gen. and sp. nov. A second species for the first genus, B. davisi, is also described. Morphometrical analysis (MANOVA and DFA) combining species of both genera showed clear differences in some shell variables although the most valuable discriminant characters are related to the female and male genital systems and to the size and shape of the osphradium. Boetersiella mainly differs from Chondrobasis in having a simple penis while a small basal penial lobe is present in the second; in addition, the distal seminal receptacle is bigger in Boetersiella and leans over the bursa copulatrix instead of over the renal oviduct as is the case in Chondrobasis. The two new genera differ from Horatia Bourguignat, 1887 in three main characters: the lack of a ctenidium, the presence in the female genitalia of only one seminal receptacle in a distal position and a penis simple (in Boetersiella) or with a small lobe close to its basis (in Chondrobasis). None of these characters are present in the type species Horatia klecakiana (Bourguignat, 1887). Both sets of character/character-states also differ from the other two valvatiform genera described for the Iberian Peninsula, Neohoratia Schütt, 1961 and Tarraconia Ramos and Arconada (in Ramos et al., in press). Comparisons with other European valvatiform genera were made although the lack of accurate anatomical data for most of them prevented any cladistical approach.