ResurrectingHelix straminea, a forgotten escargot with trans-Adriatic distribution: first insights into the genetic variation within the genusHelix(Gastropoda: Pulmonata)

Abstract

Helix is a genus of large Western Palaearctic land snails, particularly diverse in the Mediterranean region. Despite the large size and attractiveness of its members, it has an unsettled taxonomy, and no data are available on its intrageneric phylogenetic relationships. One of the problematic Helix taxa is the widely distributed, economically important, and conchologically very variable H. lucorum. Two distinct forms may be encountered under this name in the Apennine Peninsula: a typical one in the north, and a form originally described as Helix straminea in central and southern Italy. To evaluate the status of H. straminea and its relationships to Italian and Balkan Helix fauna, we combined shell morphology, geometric morphometrics, and phylogenetic analysis based on two mitochondrial genes. Distribution data were improved by drawing information from unambiguously identifiable photographs posted online. Based on our results, Helix straminea is redescribed as a separate species, and we find it to have a disjunctive trans-Adriatic range with closest relatives in the western Balkans. We provide insight into relationships and intraspecific variability within Helix, a first step towards a comprehensive revision of the genus. On the example of Italian Helix fauna, we demonstrate how understanding of snail zoogeography may change with improving taxonomy. © 2014 The Linnean Society of London