Diphyoropa saturni Gore Hill, AM C.

Diphyoropa saturni (Cox, 1864)

(Figs 10H; 12F, G; 13F, G; 15A; 16A; 17A; 27A, B)

Helix saturni Cox, 1864: 35.

Diphyoropa saturni (Cox): Hyman and Stanisic 2005: 292; Stanisic et al. 2010: 224.

(for additional synonymy see Hyman and Stanisic 2005)

Type locality. Darling Point, Sydney, NSW.

Diagnosis. Shell very small, coppery brown with a flat spire and evenly coiled whorls Protoconch sculpture bimodal with the first two thirds of the protoconch having broad, irregularly spaced spiral cords that weaken on the last third where broad, curved radial ridges develop and eventually dominate. Teleoconch sculpture of prominent, almost straight, widely to closely spaced radial ribs and cancellate microsculpture. Umbilicus wide to very wide Vshaped. Penis tubular, internally with longitudinal pilasters; epiphallus long.

Material examined (for this study). Specimens from Gore Hill Cemetery, St. Leonards (AM C.462489) and Rocky Point, Concord West (AM C.462488) were dissected and drawn. Examples from Concord West, Parriwi Park at Mosman (AM C.475921) and Newington Nature Reserve, Silverwater (AM C.462495, AM C.462525) were sequenced for DNA. Specimens from Rocky Point, Concord West provided shell measurements. These represented the living populations closest to the Darling Point type locality for the species that could be located for this study.

Description. For detailed conchological diagnosis and description refer to Hyman and Stanisic (2005).

Reproductive organs with hermaphroditic duct narrow and very elongated with a thin whip-like end at junction with ovotestis. Ovotestis containing two clumps of alveoli with more than two short alveolar lobes per clump. Spermatheca with a medium sized spherical to oval bulb. Penial retractor muscle a flat ribbon, less than half length of penis, inserting at the junction of penis and epiphallus. Epiphallus less than penis length, diameter wider than vas deferens, entering penis through a simple pore surrounded by a thickened oval-shaped, muscular collar, no other evidence of a verge. Penis tubular, with slight constriction at junction between lower section and long preputial tube. Penis with longitudinal pilasters becoming vague thickenings toward atrium. Vagina shorter than penis. Atrium very short. Based on two dissected specimens (AM C.462488, AM C.462489).

Distribution and habitat. Southern outskirts of Sydney (Woronora River) northward along the coast to Nelson Bay and Shoal Bay and inland to Gloucester, NSW. Introduced to Lord Howe Island (Stanisic et al. 2010). Sclerophyll woodland and forest (particularly turpentine/ironbark woodland on shale) to suburban gardens and wasteland; found living on the underside of logs, rocks and under accumulated fallen bark and leaf litter.

Remarks. The anatomy of Diphyoropa saturni which was described but not figured in Hyman and Stanisic (2005) is illustrated here for the first time. Hyman and Stanisic (2005: 293) mention penial pilaster development in their dissected specimens: “upper chamber with several longitudinal pilasters”. This feature was not observed in the dissected specimens from Concord West and Gore Hill Cemetery and may be due to seasonal variation (= regression) in the development of reproductive structures. DNA results show low levels of divergence between specimens from Concord West, Parriwi Park and Newington Nature Reserve in the Sydney metropolitan area.

The Wombeyan Caves sample (AM C.318805) cited in Hyman and Stanisic (2005) represents a different taxon as yet undescribed and the range of D. saturni is here restricted accordingly.