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.