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An integrative taxonomic study reveals carychiid microsnails of the troglobitic genus Zospeum in the Eastern and Dinaric Alps (Gastropoda, Ellobioidea, Carychiinae)

Inäbnit, Thomas, Jochum, Adrienne, Kampschulte, Marian, Martels, Gunhild, Ruthensteiner, Bernhard, Slapnik, Rajko, Nesselhauf, Claudia, Neubert, Eike
Organisms, diversity, & evolution 2019 v.19 no.2 pp. 135-177
Gastropoda, X-radiation, cryptic speciation, genetic analysis, micro-computed tomography, morphometry, mountains, polyphyly, scanning electron microscopy, snails, Alps region, Southern European region
The minute snails of the troglobitic genus Zospeum are known from the southeastern Alps through the Dinarides and from the Pyrenees to the Cantabrian Mountains. The majority of Zospeum has been described from the northernmost region of Southeast Europe, the geographical focus of our study. The taxonomic value of the few available morphological shell characters has been debated for nearly as long as the genus is known. Recent results of genetic studies questioned the established taxonomic system based on morphological characters in the 1970s, with one species (Z. isselianum) appearing to be polyphyletic. Here, we present a comprehensive revision of Zospeum from the Alpine and Dinaride regions, using an integrative approach including genetic methods, morphometry, X-ray micro computer tomography (micro-CT), and SEM. We reveal 25 species and describe 5 new to science. Genetic analysis separated the genus into five clades, strongly challenging the previously valid taxonomic system and revealing several species polyphyletic. The various methods used for morphological characterization often proved useful in separating species showing high incidence of cryptic speciation in the genus. Radular investigation, using SEM, uncovered new insights about the taxonomic value of the configuration of the radular ribbon within Zospeum as well as Zospeum’s dentitional affinity within the Ellobioidea.