Parmavitrina Iredale, 1937
Parmavitrina Iredale, 1937c: 8.
Type species: Helicarion planilabris Cox, 1866, by monotypy; feminine
Desidarion Iredale, 1941: 8.
Type species: Desidarion dispositus Iredale, 1941, by monotypy; masculine
Diagnosis. Shell. Medium to large, ear-shaped, last whorl large and sometimes widely flared, umbilicus closed, shell glossy, protoconch and teleoconch sculptured with fine to very fine spiral grooves or smooth (Figs 22, 23).
Fig. 22. Shells of Parmavitrina. A. P. planilabris, AM C.103630. B. P. rubrica AM C.376379 (size indicative; photographer; AM). C. P. disposita, probable holotype of Desidarion rubricus Iredale, 1941, AM C.101147 (size indicative; photographer: AM). D. P. megastoma, AM C.448244. E. P. maculosa, AM C.448344. F. P. flavocarinata, AM C.512373. Scale bar – 10 mm.
Animal. Grey to dark brown, usually with spots or mottling on sides of tail and mantle lobes and shell lappets. Tail keeled. Mantle lobes small to moderately large, cephalic shield formed from median lobe or from fused left and median lobes, shell lappets moderately small to moderately large, connected by narrow collar; right lappet rounded (Fig. 24).
Genitalia. Ovotestis of 3-5 lobes embedded in digestive gland. Carrefour and talon usually embedded in albumen gland. Spermoviduct folded 3-4 times. Distal portion of free oviduct with elongate capsular gland with no internal sculpture, remainder of free oviduct with longitudinal pilasters internally. Bursa copulatrix relatively short, internally with longitudinal pilasters (duct) and weak transverse ridges (sac), inserted on vagina. Vagina short to moderately long, internally with longitudinal pilasters. Epiphallus enters penis through a verge or thickened ring; epiphallic caecum absent; near flagellum, epiphallus often swollen with internal cryptae; epiphallic flagellum with axial filament present, containing spiraling rows of internal cryptae with a long slender tail. Spermatophore a soft-walled capsule with hard tail-pipe; branching spines present in spiraling pattern on base of capsule and along part of tail-pipe; sometimes with a single long spine towards end of tail-pipe.
Remarks. Parmavitrina was introduced as a monotypic subgenus of Helicarion based on its expansive mouth, flattened upper surface and degenerate base (Iredale, 1937a). Another large semislug, Desidarion dispositus, was described a few years later as being similar to Parmavitrina, but due to its less flattened shell and complete base it was placed in a separate genus (Iredale, 1941). The anatomy of P. planilabris was described by Hyman and Ponder (2010) but no anatomical details have previously been known for Desidarion, beyond a few brief notes given to justify taking Desidarion out of synonymy with Helicarion (Hyman and Ponder, 2010). In the current study, shell shape analysis reflected the groupings shown by Stanisic et al. (2010), with D. dispositus and D. rubricus showing a significantly lower H/D ratio compared to P. planilabris and P. megastoma. However, mitochondrial phylogeny and comparative anatomy indicated that these similarities are superficial and that the two genus names are synonymous with the older Parmavitrina having priority. Anatomical comparisons show that Parmavitrina and Desidarion are unified by their large size, flattened shell with a wide aperture, and spermatophore with spines situated primarily on the capsule rather than the tail-pipe (corresponding to internal cryptae in the epiphallus and very few in the flagellum).
In the phylogenetic tree, Parmavitrina megastoma clustered with two undescribed species. Individuals from the three populations differed in shell size and aperture width: the largest species (from Bruxner Park, north of Coffs Harbour) had a very widely flared last whorl and wide aperture, the smallest species (from Gibraltar Range National Park) had a less flared last whorl and narrower aperture, and the third species was intermediate. The three species also differed anatomically. The intermediate species most closely matches the holotype of P. megastoma and the other two species are described below as P. maculosa sp. nov. and P. flavocarinata sp. nov. These three closely related species differ from the rest of Parmavitrina in several ways; they have a more reduced shell of fewer than 3 whorls, a more slender penis with a verge, a longer vagina and bursa copulatrix, and a more slender flagellum forming a spermatophore with short, highly branched spines. However, this clade of three species groups with the other members of Parmavitrina based on both morphology and molecular phylogeny and does not warrant recognition as a separate genus.