Planorbacochlea reticulata, Shea & Colgan & Stanisic, 2012

Shea, M., Colgan, D. J. & Stanisic, J., 2012, 3585, Zootaxa 3585, pp. 1-109 : 58-59

Planorbacochlea reticulata n. sp.

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

Etymology. From the Latin reticulatus = netlike, for the fine lattice-like network sculpture of the protoconch.

Diagnosis. Shell very small, pale orange-brown to cinnamon, biconcave with depressed spire. Protoconch sculpture strongly cancellate consisting of 23 to 26 prominent, crowded, very narrow, high spiral cords and numerous, prominent and crowded radial ribs and ridges forming a distinct lattice, with beads forming at their intersection. Teleoconch sculpture of numerous, prominent, quite uniformly spaced, slightly sinuate, weakly prosocline radial ribs; microsculpture cancellate with prominent microradial ribs and low microspiral cords. Epiphallus equal in length to penis, entering penis through a simple pore. Verge absent. Penis tubular with an expanded apical portion, internally with eight short segmented, longitudinal pilasters.

Type material examined. Holotype. AM C.377860, Gladstone State Forest . Zeehan Rd at Cooks Creek Trail, NSW (30°31’ 29” S, 152° 44’ 31” E), dry rainforest regrowth, in litter, 13.xi.1999, coll. J. Waterhouse, M. Shea.

Paratypes. AM C.472877, same data as holotype .

Other material examined. Clouds Creek State Forest: AM C.128278, AM C.128318. Dorrigo National Park: AM C.128349, AM C.128366, AM C.128369, AM C.140427, AM C.340427, AM C.377902, AM C.140256, AM C.377946. New England National Park: AM C.377497, AM C465278, AM C.465283, AM C.465294, AM C.465643, AM C.465645. Irishman State Forest: AM C.377520. Bosterbrick: AM C.377817. Nymboi-Binderay National Park: AM C.377823. Gladstone State Forest: AM C.377879. Roses Creek State Forest: AM C.377881.

Description. Shell very small, pale orange-brown to cinnamon, biconcave with depressed spire. Whorls 3.12–4.00, tightly coiled, the last inflated and descending in front. Sutures strongly impressed. Shell diameter 2.90–3.45 mm (mean 3.15 mm), height 1.48–1.84 mm (mean 1.61 mm), H/D 0.47–0.56 (mean 0.52). Protoconch flat, of 1.25 whorls, diameter 0.42–0.59 mm. Protoconch sculpture strongly cancellate consisting of 23 to 26 prominent, crowded, very narrow, high spiral cords and numerous, crowded radial ribs and ridges forming a distinct lattice, with beads forming at their intersection. Teleoconch sculpture of numerous, prominent, quite uniformly spaced, slightly sinuate, weakly prosocline radial ribs. Ribs on body whorl 100–152 (mean 127), width of interstices on the first teleoconch whorl greater than or equal to width of six ribs; on the penultimate whorl equal to width of three to less than six ribs; each rib with one, 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 9–12. Aperture broadly ovately-lunate. Parietal callus prominent, transparent. Umbilicus wide cup-shaped, diameter 0.71–0.97 mm (mean 0.84 mm), D/U 3.41–4.18 (mean 3.75). Based on 13 measured adults.

Reproductive tract with ovotestis containing two clumps of alveoli, with more than two alveolar lobes per clump. Hermaphroditic duct corrugated, crescent-shaped. Spermatheca with a medium-sized oval bulb. Penial retractor muscle inserting at the junction of the penis and epiphallus. Epiphallus equal in length to penis, entering penis through a simple pore. Penis tubular with an expanded apical portion, internally with eight short segmented, longitudinal pilasters. Vagina shorter than penis. Atrium short.

Distribution and habitat. Widespread through the Bellinger, Kalang and upper Nymboida River catchments, NSW; found in a variety of habitats including tall dry sclerophyll forest, dry rainforest, subtropical rainforest, wet sclerophyll forest with rainforest understorey and warm temperate rainforest, living on the undersides of logs and rocks.

Remarks. The protoconch sculpture of Planorbacochlea reticulata n. sp. differs from that seen in other Planorbacochlea species and some species currently assigned to Cancellocochlea n. gen. in that the lattice is formed by well defined, narrow, radial and spiral elements. Species with similar protoconch types are also known from scattered localities outside the known range (e.g. Bridal Veil Falls, NE Comboyne Plateau). Additional fieldwork is required to determine the full geographic range of the phenotype. Although not resolved by present DNA studies, we consider it likely that this protoconch type represents yet another genus. Nonetheless knowledge of this possibility is considered too rudimentary to name the genus in the context of the overall charopid fauna of north-eastern NSW.

P. reticulata as currently defined has a wide distribution compared with other charopids examined in this study. The majority of material examined has been categorised on the basis of a cancellate protoconch sculpture identified by means of a light microscope. The region (in mid north-eastern NSW) is known to harbour numerous taxa with cancellate protoconchs differentiated only by their micro-architecture. Further detailed examination by scanning electron microscopy may yet reveal more than one species referred here to P. reticulata .