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

ABSTRACT

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.

KEYWORDS:

• Biogeography
• cancellate
• Charopidae
• generic framework
• malleate
• Mollusca
• protoconch radial
• sculpture
• spiral

Acknowledgements

First and foremost, the research presented in this paper could not have been done without the constant encouragement and constructive feedback of Dr John Stanisic, an expert in his own right on Charopidae and to whom I owe special thanks. I am most grateful to my supervisors, Professor Jane Hughes and Dr Chris Burwell from Griffith University, for their ongoing feedback, support and encouragement. For the use of their SEM micrographs, I thank Dr Isabel Hyman, Michael Shea and Dr Jonathon Parkyn. For the loan of material, I acknowledge the staff of Queensland Museum, Brisbane and the Australian Museum, Sydney. I also especially thank the reviewers of this paper for their comments.

Disclosure statement

No potential conflict of interest was reported by the author.

ORCID

Lorelle Holcroft http://orcid.org/0000-0002-5154-103X