Planorbacochlea graemei, Shea & Colgan & Stanisic, 2012

Shea, M., Colgan, D. J. & Stanisic, J., 2012, 3585, Zootaxa 3585, pp. 1-109 : 50

Planorbacochlea graemei n. sp.

( Figs 15F; 16F; 17F; 18E; 19F)

Etymology. Named for the late Graeme Annabel who first collected this species and who made a significant contribution to our knowledge of the terrestrial micro-snails of eastern Australia.

Diagnosis. Shell very small, pale orange-brown, biconcave with weakly depressed spire. Protoconch sculpture spiral consisting of 26 prominent, closely spaced, beaded spiral cords and weak, closely spaced radial ridges becoming more pronounced toward the protoconch-teleoconch boundary. Teleoconch sculpture of numerous, prominent, quite uniformly spaced, slightly sinuate, orthocline to weakly prosocline radial ribs. Ribs on body whorl 45–68. Umbilicus wide cup-shaped.

Type material examined. Holotype. AM C.462745, Speers Point , Lake Macquarie Reserve, above end of Farm Street, NSW (32 965° S, 151 632° E), 3.viii.2005, coll. G. Annabell. Paratypes. AM C.462740, AM C.462743, AM C.472882, same data as holotype .

Description. Shell very small, pale orange-brown, biconcave with weakly depressed spire. Whorls 3.00–3.75, tightly coiled, the last inflated and descending in front. Sutures strongly impressed. Shell diameter 2.66–3.25 mm (mean 2.80 mm), height 1.44–1.58 mm (mean 1.50 mm), H/D 0.49–0.55 (mean 0.53). Protoconch flat, of one whorl, diameter 0.35–0.48 mm. Protoconch sculpture spiral consisting of 26 prominent, closely spaced, beaded spiral cords and weak, closely spaced radial ridges becoming more pronounced toward the protoconch-teleoconch boundary. Teleoconch sculpture of numerous, prominent, quite uniformly spaced, slightly sinuate, orthocline to weakly prosocline radial ribs. Ribs on body whorl 45–68 (mean 54), width of rib interstices on the first teleoconch whorl greater than or equal to width of six ribs; on the penultimate whorl greater than or equal to width of six ribs; each rib with two or more periostracal blades with overlapping thickenings. 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 9–18; on first quarter of body whorl 12; height of microspirals very low. Aperture broadly ovately-lunate. Parietal callus prominent, transparent. Umbilicus wide cup-shaped, diameter 0.74–0.99 mm (mean 0.85 mm), D/U 3.30–3.62 (mean 3.40). Based on 5 measured adults.

Anatomy unknown.

Distribution and habitat. Known only from the type locality at Speers Point, in littoral rainforest; recovered from litter.

Remarks. Planorbacochlea graemei n. sp. is readily separated from all others in the P. hawkesburyana complex by the combination of very widely spaced radial ribs on the teleoconch and fewer spiral cords on the protoconch.