Protoconch sculpture as a taxonomic tool in Australian charopid systematics (Gastropoda: Eupulmonata: Charopidae)

Charopidae represent one of the most speciose land snail faunas in Australia with an estimated 750 species, mostly being less than 5 mm in shell diameter. The majority of its species are undescribed. With limited available material suitable for molecular analysis, morphological methods remain the primary technique for the identification of charopid species, and recent studies have shown that the sculptural patterns on the protoconch are diagnostic in establishing a generic signature. This study attempts to establish a formal framework for the description of the protoconch patterns for those species currently considered to be members of the eastern Australian Gyrocochlea sensu lato (s.l.) group of charopids. The protoconch sculpture of 60 species and 72 putative species of Gyrocochlea s.l. were examined and grouped by sculptural pattern and location. Eleven major configurations are identified, defined and described. It is intended that this terminology will be the benchmark for future descriptions of the protoconch characteristics of Australian charopid species and their generic placement. Implications for the past generic allocation of some Gyrocochlea s.l. species are discussed. Evidence from this study also indicates that there is local geographic consistency in the distribution of the protoconch patterns and a broad latitudinal sequence of pattern turnover. The biogeographic implications of this are briefly explored.