Planorbacochlea parriwiensis, Shea & Colgan & Stanisic, 2012

Shea, M., Colgan, D. J. & Stanisic, J., 2012, 3585, Zootaxa 3585, pp. 1-109 : 43-48

Planorbacochlea parriwiensis n. sp.

( Figs 20E; 21E; 22E; 23E; 24C; 25H; 26H; 27H)

Etymology. Named for Parriwi Park, Mosman, Sydney, New South Wales.

Diagnosis. Shell very small, orange-brown to brown, biconcave with weakly depressed spire. Protoconch sculpture strongly reticulate (lattice-like) consisting of 15 to 17 prominent, widely spaced, spiral cords and prominent widely spaced, broad radial ribs. Teleoconch sculpture of numerous, prominent, quite uniformly spaced, slightly sinuate, orthocline radial ribs. Ribs on body whorl 55–91. Umbilicus wide, cup-shaped. Penis club- or pear-shaped with a long tapering distal portion, apically with a verge approximately one third length of penis, pilasters absent. Verge bulbous with a terminal pore.

Type material examined. Holotype. AM C.462433, Parriwi Park, beside Spit road, next to Scout Hall, The Spit, Sydney, NSW (33° 48' 37.8” S; 151° 14' 47.5” E), 25.iv.1999, coll. M. Shea. Paratypes. (All Sydney Basin, NSW) Parriwi Park : AM C.462478, AM C.472885. Chinamans Beach : AM C.462509, AM C.462513. North Balgowlah : AM C.464075.

Description. Shell very small, orange-brown to brown, biconcave with weakly depressed spire. Whorls 3.50–4.37, tightly coiled, the last inflated and descending in front. Sutures strongly impressed. Shell diameter 2.96–3.82 mm (mean 3.37 mm), height 1.64–2.09 mm (mean 1.84 mm), H/D 0.53–0.56 (mean 0.54). Protoconch flat, of 1.25 whorls, diameter 0.43–0.60 mm. Protoconch sculpture strongly reticulate (lattice-like) consisting of 15 to 17 prominent, widely spaced, spiral cords; and prominent widely spaced radial ribs. Teleoconch sculpture of numerous, prominent, quite uniformly spaced, slightly sinuate, orthocline radial ribs. Ribs on body whorl 55–91 (mean 77), width of interstices on the first teleoconch whorl equal to width of four to less than six ribs; on the penultimate whorl equal to width of four to less than 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 6–7; on first quarter of body whorl 14–15; height of microspirals variable. Aperture broadly ovately-lunate. Parietal callus prominent, transparent. Umbilicus wide, cup-shaped, diameter 0.86–1.23 mm (mean 1.05 mm), D/U 2.98–3.72 (mean 3.31). Based on 10 measured adults.

Reproductive organs with ovotestis containing two clumps of alveoli, with more than two alveolar lobes per clump. Hermaphroditic duct narrow crescent shape. Penial retractor muscle inserting at the junction of the penis and epiphallus. Epiphallus shorter than penis, entering latter through a bulbous verge having a terminal pore. Verge approximately one third length of penis, penis club- or pear-shaped, with a long tapering distal portion; pilasters absent. Vagina shorter than penis. Atrium very short.

Distribution and habitat. Northern Sydney, NSW; in urban bushland remnants in sclerophyll forest and moister woodland to dry vine thicket in sheltered gullies, found on underside of logs, wood and stones.

Remarks. P. parriwiensis n. sp. is distinguished from other Sydney Basin Planorbacochlea by the protoconch sculpture. The strongly reticulate (lattice-like) pattern of P. parriwiensis comprising widely spaced spiral cords and widely spaced radial ribs contrasts with the densely crowded spiral pattern seen in P. hawkesburyana with which it is sympatric. The difference is suggestive of generic differentiation from Planorbacochlea . However, the currently available DNA data show the species to be more closely aligned with that genus than any other lineage investigated in the current study.