Homoplasy in shells discombobulated the taxonomy: revision of the larger helicarionid land snails of northern Queensland, Australia (Stylommatophora: Helicarionidae)

Abstract

ABSTRACT Helicarionid land snails with large shells have been placed in three genera: Malandena, Pravonitor and Elatonitor. These taxa are revised herein using comparative morpho-anatomy and mitochondrial phylogenetics. We demonstrate that these species represent three independent radiations, but this is not reflected in the current generic arrangement. Phylogenetic reconstruction revealed that these genera do not form a monophyletic group, and we conclude that large shells have evolved multiple times among helicarionids in Queensland, Australia, presumably as an adaptation to moist environments. Species belonging to Pravonitor have a medium-sized to large, glossy shell, often with a peripheral band. Among other traits, they always have a single-chambered, internally pustulose or ridged penis, an epiphallus with a slender flagellum, and a long epiphallic caecum with medial penial retractor muscle attachment. This genus comprises eight species: Pravonitor kreffti, P. ferrugineus, P. insularum, P. annulus, P. aquilonia comb. nov., P. monteithi comb. nov., P. septentrionalis sp. nov. and P. stuarti sp. nov. We describe Geminitor gen. nov. for Geminitor laura comb. nov., G. villaris comb. nov., G. kullaensis sp. nov., G. macveae sp. nov. and G. wenlockensis sp. nov. Geminitor has a small to medium-sized shell, a long, two-chambered penis, an epiphallus with a slender flagellum, and an epiphallic caecum with basal penial retractor muscle attachment. The unavailable genus name Malandena is subsumed under Elatonitor, which now contains Elatonitor montanus and E. suturalis comb. nov. Elatonitor has a large glossy shell with an angulate periphery, a long, narrow, single-chambered penis with longitudinal pilasters, an epiphallus with a broad flagellum, and no epiphallic caecum. While this study has nearly doubled the number of known large helicarionid species in Far North Queensland, there are still knowledge gaps and we recommend further surveys to search for undocumented species, improve our understanding of species distribution and undertake vital conservation assessments. http://www.zoobank.org/urn:lsid:zoobank.org:pub:83362BEC-6E6B-4B65-AC1E-F49762C744B8