Gyrocochlea vinitincta ( Cox, 1868 )

Shea, M., Colgan, D. J. & Stanisic, J., 2012, 3585, Zootaxa 3585, pp. 1-109 : 86-87

Gyrocochlea vinitincta ( Cox, 1868)

( Figs 36A; 39I; 40H; 41H)

Helix vinitincta Cox, 1868: 18

Gyrocochlea vinitincta (Cox) : Hedley 1924: 218; Iredale 1937: 322; Iredale 1941a: 268; Stanisic 1990: 79; Stanisic et al. 2010: 202.

Diagnosis. Shell small, reddish-brown, strongly biconcave with a deeply depressed spire. Protoconch sculpture very finely cancellate comprising about 40 very closely spaced, fine spiral lirae and fine radial threads, beaded at their intersections. Teleoconch sculpture of numerous, prominent, quite uniformly, closely spaced, slightly sinuate, strongly prosocline radial ribs. Ribs on body whorl 106–153 (mean 129). Umbilicus wide U-shaped.

Type material examined. Holotype. AM C.63490, Upper Richmond River , NSW (28° 30’ 30” S, 152° 59’ E), under logs in brushes, 1867, coll. J. MacGillivray. Paratype. AM C.103624, same data as holotype .

Other material examined. Whian Whian State Forest: AM C.139751. Mt Warning: QMMO 10487, QMMO 19798. Lamington National Park: AM C.63886, QMMO 79060.

Description. Shell very small, reddish-brown, strongly biconcave with a deeply depressed spire. Whorls 3.75–4.50, tightly coiled, the last inflated and descending in front. Sutures strongly impressed. Shell diameter 7.55–9.28 mm (mean 8.56 mm), height 4.61–5.36 mm (mean 4.92 mm), H/D 0.56–0.61 (mean 0.58). Protoconch flat, of 1.25 whorls, diameter 0.82–1.10 mm. Protoconch sculpture very finely cancellate comprising very closely spaced, spiral lirae intersected by numerous fine radial threads, beaded at their intersections; number of protoconch spirals 40. Teleoconch sculpture of numerous, prominent, quite uniformly, closely spaced, slightly sinuate, strongly prosocline radial ribs. Ribs on body whorl 106–153 (mean 129), width of interstices on the first teleoconch whorl equal to width of four to less than width of six ribs; on the penultimate whorl equal to width of three to less than width of four ribs; each rib with multiple periostracal blades; overlapping thickenings absent. Interstitial sculpture of low prominent microradial ribs and low, weaker microspiral cords forming weak beads at their intersection; number of microradials between ribs on the first teleoconch whorl 12; on first quarter of body whorl 14. Aperture broadly ovately-lunate. Parietal callus prominent, transparent. Umbilicus wide U-shaped, diameter 1.52–2.05 mm (mean 1.74 mm), D/U 3.97–5.69 (mean 4.94). Based on 12 measured adults.

Reproductive tract with ovotestis containing two clumps of broad brain-shaped alveoli (one largely missing in dissected specimen); with numerous short alveolar lobes per clump. Spermatheca with small oval bulb. Hermaphroditic duct twisted or kinked medially and kinked at junction with albumen gland. Penial retractor muscle inserting at the junction of the penis and epiphallus. Epiphallus longer than penis, entering penis through a simple pore (verge absent). Penis tubular with an expanded apical portion, internally with 4–5, anastomosing longitudinal pilasters. Vagina shorter than penis. Atrium short.

Distribution and habitat. Richmond River, north-eastern NSW to the Border Ranges, south-eastern Queensland; found in lowland to mid altitude rainforest mainly on basaltic soils, living on the underside of logs and fallen bark.

Remarks. Gyrocochlea vinitincta Hedley, 1924 is the largest biconcave charopid in north-eastern New South Wales and south-east Queensland and is distinguished by the very large (for family) dark red-brown shell with deep whorls, sunken spire and crowded ribs on the teleoconch (particularly on the first teleoconch whorl). Stanisic (1990) mistakenly refers to the presence of a verge in the dissected specimen of this species from Mount Warning National Park. Results of the current study indicate that the vergic structure referred to was in fact an eversion of the muscular ring surrounding the epiphallic pore. The revised diagnosis and description given above are based solely on material examined here.