Nitor circumcincta ( Cox, 1868 )

Hyman, Isabel T. & Ponder, Winston F., 2010, A morphological phylogenetic analysis and generic revision of Australian Helicarionidae (Gastropoda: Pulmonata: Stylommatophora), and an assessment of the relationships of the family 2462, Zootaxa 2462 (1), pp. 1-148 : 59-61

Nitor circumcincta ( Cox, 1868)

Figures 10D, 11D, 16B, F, 17J–L, 18E, 19E, 20D, 21E, 22A

Helix marmorata Cox, 1864: 20 [not Helix marmorata of Férussac, 1821].

Helix (Xesta) circumcincta Cox, 1868: 3 , pl. 5, figs 6a–b [nom. nov. for Helix marmorata Cox, 1864 ].

Nanina (subg. Xesta, sect. Macrochlamys ) marmorata: Tryon, 1885: 105 , pl. 35, figs 39–40.

Nanina marmorata: Hedley, 1888: 50 .

Microcystis circumcincta: Gabriel, 1930: 85–86 .

Melocystis circumcincta: Iredale, 1937c: 5 ; Smith, 1992: 238.

Material examined. New South Wales, Australia: Possible syntype: AM C104161 (one shell measured, photographed), Kiama (34º40' S, 150º51' E), pre 1864, G. Masters .

Other material: AM C365822 (one specimen dissected; juvenile), bottom of Macquarie Pass , ca. 300 m along walking track (34º34.37' S, 150º40.6' E), in leaf litter from subtropical rainforest, 6 Jul. 1999, L. Brincat ; AM C356607 (two specimens dissected; one radula examined), NW of Kiama, near Jamberoo , Jamberoo Mt., (34º39' S, 150º42' E), in leaf litter in rainforest, 8 Nov. 1987, G. Hunt & party .

Description. External morphology: Shell ( Figures 16B, F, 19E, 20D, 21E) 4.3 whorls, golden brown with a broad peripheral colourless band; shell shape and sculpture as for genus; whorl profile flattened above and below sub-angular periphery; umbilicus open, very narrow U-shape. Animal cream and grey. Mantle laps moderately small, as for genus; mantle lobes as for genus. Caudal horn moderately small; caudal foss diamond-shaped slit in tail.

Mantle cavity ( Figure 10D): As for genus. Mantle with faintly visible minor blood vessels, pigmentation of black and white spots, mantle gland absent.

Digestive system: As for genus.

Genital system ( Figures 18E, 22A): As for genus. Bursa copulatrix internally with longitudinal pilasters. Penis long; epiphallus enters penis through two fleshy lips; penis internally smooth, four to five longitudinal penis pilasters present, penial diverticulum absent. Penial sheath present, enclosing only base of penis. Epiphallus longer than penis, internally with longitudinal pilasters. Spermatophore as for genus.

Radula (17J–L): As for genus. Radular formula (~58.10.1.10.~58) × at least 80 rows.

Range and habitat. Nitor circumcincta is found from Moruya in southeastern New South Wales to the Royal National Park, south of Sydney, usually in rainforest and vine thickets but sometimes in wet sclerophyll forest. There is also a single specimen known from south of Eden, close to the New South Wales-Victoria bor- der. Specimens are usually found under rocks or in leaf litter.

Remarks. Nitor circumcincta is synonymised here with Helix marmorata ( Cox 1864) . However, the species referred to as Microcystis marmorata by Odhner (1917) was probably Nitor subrugata ( Iredale 1941) .

Nitor circumcincta has previously been included in the genus Melocystis . However, Iredale (1941) grouped Melocystis (then containing only circumcincta ) with Nitor in the family Nitoridae . In the current study, N. circumcincta did not group with the other Nitor species in the phylogenetic analysis ( Figure 4). Despite this, the strong anatomical similarities between N. circumcincta , N. wiangariensis and N. subrugata (flagellum type, epiphallic caecum and attachment of penis retractor muscle, vagina length, internal structure of the penis, spermatophore sculpture) suggest that this is the best current placement of this species. Nitor circumcincta lacks the peripheral keel present on the shells of N. wiangariensis and N. subrugata ; however, it shares the flattened whorl profile seen in both species and has a slightly angulate periphery.