A revision of eastern Australian land snails placed in Nitor Gude (Helicarionidae, Stylommatophora)

Abstract

Nitor Gude, 1911 is a genus of helicarionid land snails currently comprising eight species ranging from southern New South Wales to northern Queensland. We comprehensively revise the taxonomy of this group based on comparative morphology and on mitochondrial genes cytochrome c oxidase subunit I and 16S rRNA, provide a new generic diagnosis, revise species descriptions and describe four new species. Two species, ‘N.’ reisi Stanisic, 2010 from northern Queensland and ‘N.’ whitneyae Stnaisic, 2010 from mid-eastern Queensland, are removed from Nitor. Revised species descriptions are given for N. subrugatus (Reeve, 1852), N. medioximus Iredale, 1941, N. circumcinctus (Cox, 1868), N. wiangariensis Hyman, 2007 and N. pudibundus (Cox, 1868); N. helmsianus Iredale, 1941 (previously considered a synonym of N. subrugatus) is reinstated; and new species N. glenugie, N. sheai, N. benjamini and N. pipinna are described. Helix graftonensis Cox, 1864 is synonymised with N. subrugatus. We demonstrate that Nitor is closely related to Lord Howe Island taxa Epiglypta Pilsbry, 1893, Gudeoconcha Iredale, 1944, Howearion Iredale, 1944 and Parmellops Iredale, 1944; the five genera are united by a combination of characters including the presence of a distinct vagina, a slender epiphallic flagellum forming a simple spermatophore and an epiphallic caecum with terminal attachment of the penial retractor muscle.