Integrative taxonomy of Magilaoma , Pedicamista and Pasmaditta , with descriptions of one new genus and four

Context

Australian punctoids are a poorly known group of small to minute land snails with considerable undescribed diversity, especially in Tasmania. Very few studies to date have included anatomical and molecular data. Herein we address three endemic genera with varying degrees of reduced shell sculpture.

Aims

Our aim was to comprehensively revise the systematics of the genera Magilaoma, Pedicamista and Pasmaditta, tiny punctoids of approximately 2–5 mm in shell width, using comparative morpho-anatomy and phylogenetic analyses of mitochondrial (COI, 16S) and nuclear (ELAVI8, ITS2) DNA.

Taxa

Family Punctidae: Magilaoma, Pedicamista; Family Cystopeltidae: Pasmaditta.

Methods and key results

We demonstrate that these taxa, while very similar and often misidentified as one another, form three independent lineages. The first lineage, made up of genera Magilaoma (excluding M. canobla) and Pedicamista along with new species, has a malleate protoconch, radula with reduced accessory cusps, and reproductive system with what appears to be an internalised epiphallus. We treat Pedicamista as a junior synonym of Magilaoma, redescribe M. penolensis (including new records from Western Australia) and M. coesa comb. nov. and introduce new taxa M. tasmanica sp. nov. and M. saxilitoralis sp. nov. For the second lineage, a single undescribed species most closely related to the Norfolk Island punctids, we introduce the name Gahniella undulata gen. et sp. nov. This arboreal species has a spirally lirate protoconch, reduced teleoconch ribs and distinct spiral microsculpture, and differs from Magilaoma in the presence of an epiphallus, a penis with only a short blind tip, and radular teeth with more elongate accessory cusps. The third radiation comprising two species diverges from within Cystopeltidae; this family placement is supported by an incomplete secondary ureter and a charopid-like rather than punctid-like radula. We redescribe Pasmaditta jungermanniae and introduce new species Pasmaditta genisys sp. nov. We also demonstrate that genus Planilaoma belongs to the family Cystopeltidae rather than Charopidae and introduce two new combinations for outgroup taxa, Planilaoma sitiens comb. nov. and Paralaoma canobla comb. nov.

Conclusions

The secondary ureter and radula are confirmed as key characters distinguishing the families Punctidae and Cystopeltidae. The two punctid lineages addressed herein are differentiated by differences in protoconch and teleoconch sculpture, shell shape, the anatomy of the penial complex, and radula tooth shape.

ZooBank: urn:lsid:zoobank.org:pub:400A738A-D887-4417-A89F-4A474A40DE73