Systematics, conservation status, and biogeography of 16 new species of SinployeaSolem, 1983 (Gastropoda: Charopidae) from New Zealand.

This article focuses on the taxonomic revision and biogeographical analysis of New Zealand land snails in the genus *Sinployea* Solem, 1983, describing 17 species including 16 new to science. It provides detailed morphological descriptions, including shell and reproductive anatomy, and reassigns *Sinployea* and related genera (*Calymna*, *Flammoconcha*, and others) to the tribe Flammulinini within the subfamily Charopinae, rejecting the previously proposed subfamily Flammoconchinae. The study discusses the distribution of *Sinployea* species in relation to the tectonic history of the southwest Pacific, highlighting patterns of allopatry and disjunctions linked to extinct subduction zones, fault zones, and volcanic plateaus such as the Ontong Java, Manihiki, and Hikurangi Plateaus. Conservation threat rankings for New Zealand *Sinployea* species are updated using the New Zealand Threat Classification System (NZTCS), with most species considered naturally uncommon or data deficient, and one species (*Sinployea australis*) presumed extinct based on recent survey efforts. The findings emphasize the influence of geological processes on species distributions and advocate for further systematic sampling and phylogenetic research to clarify evolutionary relationships within this diverse group of microsnails.