Comboynea boorganna, Shea & Colgan & Stanisic, 2012

Shea, M., Colgan, D. J. & Stanisic, J., 2012, 3585, Zootaxa 3585, pp. 1-109 : 73-74

Comboynea boorganna n. sp.

( Figs 29E; 31E; 33E; 35E; 37F, H; 39D; 40D; 41A)

Etymology. For the Boorganna Nature Reserve.

Diagnosis. Shell very small, orange-brown, biconcave with depressed spire. Protoconch sculpture primarily spiral consisting of 22 prominent, crowded, low, broad spiral cords and very weak, irregularly spaced, underlying radial ridges. Teleoconch sculpture of numerous, prominent, quite uniformly spaced, slightly sinuate, opisthocline radial ribs. Ribs on body whorl 99–129 (mean 108). Umbilicus wide U-shaped. Epiphallus shorter than penis, entering penis through a simple bud-like verge with a lateral slit. Penis with an expanded apical portion becoming tubular distally;. no pilasters present.

Type material examined. Holotype. QMMO80158 , Boorganna Nature Reserve , ca. 6.3 km SW of Comboyne, NSW (31° 38´S, 152° 25´E), rainforest, under logs, 21.xi.1989, coll. J. Stanisic, D. Potter. Paratypes. QMMO31451 , AM C.163287, both same data as holotype .

Description. Shell very small, orange-brown, biconcave with depressed spire. Whorls 3.75–4.00, tightly coiled, the last inflated and descending in front. Sutures strongly impressed. Shell diameter 3.79–3.97 mm (mean 3.88 mm), height 2.07–2.28 mm (mean 2.18 mm), H/D 0.54–0.59 (mean 0.56). Protoconch flat, of 1.12–1.25 whorls, diameter 0.51–0.69 mm. Protoconch sculpture primarily spiral consisting of 22 prominent, crowded, low, broad spiral cords and very weak, irregularly spaced, underlying radial ridges. Teleoconch sculpture of numerous, prominent, quite uniformly spaced, slightly sinuate, opisthocline radial ribs. Ribs on body whorl 99–129 (mean 108), width of interstices on the first teleoconch whorl equal to width of four to greater than or equal to width of six ribs; on the penultimate whorl equal to width of four to greater than or equal to width of six ribs; each rib with two or more periostracal blades. 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 11–12; on first quarter of body whorl 12–13. Aperture narrowly ovately-lunate. Parietal callus prominent, transparent. Umbilicus wide U-shaped, diameter 0.83–1.00 mm (mean 0.92 mm), D/U 3.88–4.78 (mean 4.28). Based on 5 measured adults.

Reproductive tract with ovotestis containing two clumps of alveoli, with more than two alveolar lobes per clump. Hermaphroditic duct crescent-shaped. Spermatheca with a large oval bulb. Penial retractor muscle inserting at the junction of the penis and epiphallus. Epiphallus shorter than penis, entering penis through a simple bud-like verge with a lateral slit. Penis with an expanded apical portion becoming tubular distally; no pilasters present. Vagina shorter than penis. Atrium short.

Distribution and habitat. Known only from the type locality; found in subtropical/warm temperate rainforest, living on the underside of logs.

Remarks. Comboynea boorganna n. sp. is known only from the upland rainforests (approximate altitude 700 m) of the isolated Comboyne Plateau. It is distinguished from two other yet-to-be described nautiliform charopids by the distinctly spiral protoconch sculpture (cancellate in the former). It most closely resembles Co. mountaineer n. sp. from the geographically distant Barrington Tops National Park.