Barringtonica polblue, Shea & Colgan & Stanisic, 2012

Shea, M., Colgan, D. J. & Stanisic, J., 2012, 3585, Zootaxa 3585, pp. 1-109 : 65

Barringtonica polblue n. sp.

( Figs 20G, H; 21G, H; 22G, H; 23G, H; 24F, G; 39A, B; 40A, B)

Etymology. For the type locality.

Diagnosis. Shell very small, pale golden-brown, weakly biconcave to planispiral, spire weakly depressed. Protoconch sculpture consisting of 26 to 27 low, flattened, broad spiral cords and a few very weak, widely spaced, radial growth ridges which are more noticeable at the protoconch-teleoconch boundary. Teleoconch sculpture of numerous, prominent, quite uniformly spaced, slightly sinuate, strongly prosocline radial ribs. Umbilicus wide, cup-shaped. Penis tubular with an expanded apical portion becoming tubular distally. Verge absent, no pilaster formation observed.

Type material examined. Holotype. AM C.309166, Polblue Crown Reserve , Pheasant Creek road, off Scone- Gloucester road, east of Scone , upper Hunter region, western Barrington Tops NP, NSW (31˚52’ 40” S, 151˚27’ 08” E), 2.ix.2001, coll. M. Shea. Paratypes. AM C.472874, same data as holotype ; AM C.309167, AM C.472875, both Upper Moonan Brook , upper Moonan Brook road, 2.4 km upstream of Moonan Brook picnic area, NSW (34˚57’ 10” S, 151˚18’ 33” E) .

Other material examined. QMMO 49487.

Description. Shell very small, pale golden-brown, weakly biconcave to planispiral, spire weakly depressed. Whorls 3.5–4.25, uniformly to tightly coiled (in specimens from the type locality) or rather loosely coiled (in specimens from Moonan Brook), the last weakly expanding and descending in front. Sutures strongly impressed. Shell diameter 3.61–4.44 mm (mean 4.00 mm), height 1.90–2.21 mm (mean 2.01 mm), H/D 0.50–0.51 (mean 0.51). Protoconch flat, of 1.12 whorls, diameter 0.58–0.67 mm. Protoconch sculpture consisting of 26 low, flattened, broad spiral cords and a few very weak, widely spaced, radial growth ridges which are more noticeable at the protoconch-teleoconch boundary. Teleoconch sculpture of numerous, prominent, quite uniformly spaced, slightly sinuate, strongly prosocline radial ribs. Ribs on body whorl 77–104 (mean 95) at site 3, 82–143 (mean 102) at site 2; width of interstices on the first teleoconch whorl equal to width of four to less than six ribs; on the penultimate whorl greater than or equal to width of six ribs; each rib with two or more overlapping 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 5–8; on first quarter of body whorl 8. Aperture broadly ovately to roundly lunate. Parietal callus prominent, transparent. Umbilicus wide cup-shaped, diameter 0.95–1.40 mm (mean 1.13 mm), D/U 3.18–3.85 (mean 3.54). Based on 11 measured adults.

Reproductive tract with ovotestis containing two clumps of alveoli, with three or more alveolar lobes per clump. Hermaphroditic duct narrow crescent-shaped. Spermatheca with a large sub-pyramidal bulb. Penial retractor muscle inserting on head of the penis at the junction of the penis and epiphallus. Epiphallus shorter or equal in length to the penis, entering penis through a simple valvular pore. Verge absent. Penis with an expanded apical portion becoming tubular distally; no pilaster formation observed. Vagina shorter than penis. Atrium short.

Distribution and habitat. Known only from the volcanics of the western Barrington Tops National Park, NSW; occurring in sub-alpine eucalypt woodland and forest (Snow Gum/Ribbon Gum association) with tussock grass ( Poa sp. ) groundcover on basalt, living on the undersides of logs (Polblue Crown Reserve, site 3) or on the underside of rocks of volcanic scree in vine thicket (Moonan Creek, site 2).

Remarks. There is intraspecific variation between Barringtonica polblue n. sp. sites with the Moonan Creek snails (site 2) having a higher rib count on the teleoconch. This site occurs in dry rainforest rather than the montane Snow Gum forest of the Polblue Crown Reserve (site 3). B. polblue differs from the microsympatric B. montana sp nov. by its more discoidal/planate shape, wider umbilicus, wider spaced radial ribs on the teleoconch, broader and less numerous protoconch spirals. The epiphallus is also shorter relative to the penis size compared to B. montana and the distal valvular swelling of the epiphallus is smaller.