A revision of the New Zealand Placostylus land snails using mitochondrial DNA and shell morphometric analyses, with implications for conservation

Abstract

We have analysed mitochondrial DNA and shell morphometric data from all species and subspecies of Placostylus land snails in New Zealand. These subspecies were originally described on the basis of shell morphology. The genetic data show that each of the three species P. bollonsi, P. hongii and P. ambagiosus are well differentiated and monphyletic for mitochondrial DNA, consistent with their species status. Variation among subspecies within each of the three species was minimal with sharing of haplotypes among subspecies. Morphometric analysis of shell shape characters shows large amounts of environmental plasticity. On the basis of these data we have synonymised all subspecies within each of the three Placostylus species. Consequently, the New Zealand fauna now consists of three Placostylus species, P. ambagiosus, P. hongii and P. bollonsi, and no subspecies. We recommend conservation of multiple populations within each species to ensure preservation of genetic variation.

Keywords:

• Placostylus
• conservation genetics
• Mollusca
• biogeography
• New Zealand

Acknowledgements

This research was funded by the Foundation for Research, Science and Technology through the Sustaining and Restoring Biodiversity OBI and DOC investigation No. 2386. The authors would like to thank Robert Hoare for advice on nomenclature and Chris Edkins for Figs 1, 2 and 5–8. Gary Houliston, Cor Vink and two anonymous reviewers provided comment that improved the manuscript. Department of Conservation staff assisted with permits and sampling.