Molecular phylogeny of the helicoid land snails (Pulmonata: Stylommatophora: Helicoidea), with special emphasis on the Camaenidae

Abstract

The superfamily Helicoidea is a large and diverse group of land snails belonging to the Pulmonate suborder Stylommatophora. It has an almost worldwide distribution, absent from only sub-Saharan Africa, southern South America, New Zealand and some Pacific islands (Scott, 1996, 1997). The composition of the superfamily has remained somewhat controversial. Morphological studies have suggested the inclusion of between three and nine families, with only the Helicidae and Bradybaenidae common to all classifications (Thiele, 1931; Zilch, 1959–1960; Taylor & Sohl, 1962; Shileyko, 1979; Solem, 1979; Boss, 1982; Nordsieck, 1985, 1986; Tillier, 1989; Vaught, 1989; Scott, 1997; Bouchet & Rocroi, 2005). Our recent molecular study of the Stylommatophora has demonstrated the monophyly of a ‘Helicoidea’ comprising the Helicidae, Bradybaenidae, Helminthoglyptidae, Hygromiidae, Camaenidae, Polygyridae and Sagdidae (Wade, Mordan & Naggs, 2006). In this study, we apply molecular phylogenetic techniques to investigate specifically the evolutionary relationships within this ‘helicoid’ group.