Cumberlandica impressa ponderi ( Stanisic, 2010 ) Shea & Colgan & Stanisic, 2012

Shea, M., Colgan, D. J. & Stanisic, J., 2012, 3585, Zootaxa 3585, pp. 1-109 : 28-32

Cumberlandica impressa ponderi ( Stanisic, 2010) n. comb.

( Figs 7D–F; 8D–F; 9D–F; 10D–F; 11C, E, F; 11C–E; 13B, D, E; 14D–H)

Gyrocochlea ponderi Stanisic, 2010 (in Stanisic et al. 2010): 196.

Diagnosis. Shell very small, brown with a deeply biconcave to almost flat spire, and tightly and evenly coiled whorls. Protoconch sculpture of many, widely spaced spiral cords and curved radial ribs that form on its latter part, becoming more pronounced toward the teleoconch boundary; teleoconch sculptured with numerous well developed, widely to closely spaced radial ribs; microsculpture cancellate consisting of fine microradial ribs and low microspiral cords. Umbilicus wide U-shaped to cup-shaped. epiphallus as long as penis; penis pear-shaped with apical verge and long tapering distal portion; penial verge large, open and convoluted with a lateral slit; longitudinal pilasters distally; vagina long.

Type material examined. Holotype. QMMO29399 , c. 2 km W West Head West Head Rd, Sydney NSW (33° 35’S, 150° 17’ E), rainforest/ Livistona , under burnt logs, 2.i.1990, coll. J. Stanisic, J. Chaseling. Paratypes: QMMO78945 , same data as holotype .

Other material examined. (All Sydney Basin, NSW) West Head: AM C.142929, AM C.152185, AM C.462481, AM C.463083, QMMO 46745. Whale Beach: AM C.152189, AM C.462479. Palm Beach: QMMO 29636.

Description. Shell very small, brown, biconcave with deeply depressed spire. Whorls 4.25–5.0, tightly coiled, the last ascending, in line or descending in front. Sutures strongly impressed. Shell diameter 3.98–5.26 mm (mean 4.57 mm), height 2.23–2.94 mm (mean 2.54 mm), H/D 0.51–0.60 (mean 0.56). Protoconch flat, of 1.12 whorls, diameter 0.61–0.71 mm. Protoconch sculpture consisting of 25–27 low, widely spaced, narrow spiral cords and widely spaced, orthocline to prosocline radial ribs, beginning on the final quarter of the protoconch and becoming more pronounced toward the protoconch-teleoconch boundary. Teleoconch sculpture of numerous, prominent, quite uniformly spaced, slightly sinuate, orthocline to opisthocline radial ribs. Ribs on body whorl 96–141 (mean 118), 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 four ribs; each rib with two or more overlapping periostracal blades. Interstitial sculpture of low prominent microradial ribs and low, weaker microspiral cords forming beads at their intersection; number of microradials between ribs on the first teleoconch whorl 6–9; on first quarter of body whorl 5–9; microspirals very low. Aperture narrowly ovately-lunate. Parietal callus prominent, transparent. Umbilicus wide U-shaped to cup-shaped, diameter 1.37–1.84 mm (mean 1.56 mm), D/U 2.59–3.38 (mean 2.94). Based on 24 measured adults.

Reproductive organs with ovotestis containing two clumps of alveoli with numerous finger-like alveolar lobes per clump. Spermatheca with a large oval bulb. Talon large, spherical or ovate to heart-shaped. Penial retractor muscle less than half the length of penis, inserting at the junction of the penis and epiphallus. Epiphallus longer or equal to the penis length, entering penis through a verge opening through a lateral slit. Penis pear-shaped with an apical bulb, internally with a tongue-shaped apical verge and longitudinal pilasters tapering to the atrium. Vagina shorter than or equal to length of penis.

Distribution and habitat. Southern side of Broken Bay to northern beaches, Sydney, NSW; found in mixed Livistona /Eucalyptus/Macrozamia/ Casuarina associations on volcanic rocks, and vine thicket/remnant rainforest in steep sandstone gullies living on the underside of logs, fallen palm leaves and timber.

Remarks. This subspecies can be distinguished from Cu. impressa impressa by the lower rib count and looser coiling. It differs from Cu. wombeyanensis by the much higher radial rib count (between 96 and 141 on the body whorl), more sunken spire, much tighter coiling of the whorls and wider umbilicus. It can be distinguished from Cu. wilsoniana by the more strongly, laterally compressed aperture and tighter whorl coiling. The tightly coiled whorls, deeply sunken spire, high whorl count and strongly laterally compressed aperture are characteristics of these sites and others from the Broken Bay area including the Barrenjoey headland where morphologically similar specimens occur but from which no living material was available.