Sinployea cresswelli Climo, Mahlfeld & Roscoe, 2025

Mahlfeld, Karin, Climo, Frank & Roscoe, David, 2025, Systematics, conservation status, and biogeography of 16 new species of Sinployea Solem, 1983 (Gastropoda: Charopidae) from New Zealand, Zoological Journal of the Linnean Society 204 (1) : -

Sinployea cresswelli Climo, Mahlfeld & Roscoe sp. nov.

( Figs 16, 37C, 40, 45) Vicariodiscus ‘cresswelli’ McGuinness 2001: 596; Hitchmough 2002: 130.

Charopidae sp.47 (NMNZ M.113794) Hitchmough et al. 2007: 131; Spencer et al. 2009: 213; Mahlfeld et al. 2012: appendix 1.

Material examined: New Zealand, South Island, NMNZ: M.113794, holotype ( Figs 37C, 40), Canterbury, NW of Hanmer Springs, Lewis Pass , bush edge, 42°22′44.890″S, 172°23′21.112″E, P.L. Cresswell, 17 January 1981 ; M.089001, paratype, Canterbury, Arthur’s Pass , summit, 42°54′19.801″S, 171°33′30.679″E, P.R. Jamieson, 7 March 1976 .

Other material examined: New Zealand, South Island , Westland : N of Greymouth, Rapahoe, 42°23′11.780″S, 171°13′14.827″E and 42°22′46.545″S, 171°13′59.266″E, F.M. Climo and K. Mahlfeld, 13 December 1994 (from our field notes but not re-examined) . Fox Range, rimu ( Dacrydium cupressinum ) dominant, F.J. Brook, 28 December 2015. Fiordland: Dusky Sound, Anchor Island , K. Walker, June 2014 .

Description: Shell small, depressed subglobose, thin, and fragile, 1.9 mm wide and 1.09 mm high at 3.6 whorls, coarsely ribbed and moderately tightly coiled for the group.Spire broadly domed, 263 μm high, apex emergent. Umbilicus is moderately wide, 644 μm in diameter (D/U ratio 2.95). Shell is chiefly bronze brown, with a few narrow translucent white axial bands; the base of the shell is chiefly bronze brown. Protoconch 567 μm wide, with 1.5 convex whorls, sculptured by spiral lirae but not clear enough to be counted confidently. Teleoconch of two steadily expanding, convex whorls, with a round base (rim of aperture slightly broken). Sculpture consisting of weakly protractive, sturdy primary axials traversed by narrowly spaced fine spiral lirae. These spiral cords are about twice the width of the secondary axials and form microscopic beads at the intersections with secondary axials, ~8–11 axials per interstitial space. Primary axials (~44 on first teleoconch whorl) each with a narrow, rounded ridge, crested with a short periostracal lamella (often worn off). Suture deep, and sutural slope relatively steep. Aperture ~827 μm high, round, outer lip simple. Columella short and vertical, not reflected.

Reproductive anatomy: Unknown.

Etymology: Named after our friend and shell collector, Peter Cresswell of Motueka, who collected the type material.

Distribution: Sinployea cresswelli was first collected in the 1970s at Arthur’s Pass, Southern Alps, and it is also known from Lewis Pass, Canterbury, the northeastern range limit of the species, Westland, Rapahoe, and Fox Range and Anchor Island in Dusky Sound, SW Fiordland. Sinployea cresswelli , S. charopiformis , and S. canaliculata form a group of more tightly coiled species with a wider umbilicus that are allopatric and meet in mid-western Fiordland.

Ecology: Temperate beech ( Nothofagus ) forest.

Related species: Sinployea cresswelli is the most tightly coiled and coarsely ribbed species of the southern South Island Sinployea species. Sinployea charopiformis and S. canaliculata have smaller protoconchs than S. cresswelli , and S. canaliculata shells are characterized by a channelled suture. Sinployea fiordlandica has a flat to slightly depressed spire and closely spaced teleoconch axials, and the S. australis shell is the most finely ribbed one with a weakly elevated spire. The latter two species also have more loosely coiled shells with a smaller umbilical diameter than the other three southern species. The sutural slope in S. cresswelli is relatively steep, as in S. fiordlandica , S. waipoua , and S. haupatoto , for example.

Conservation status: In total,>300 collection events are recorded in the Te Papa holdings of land snails from the Paparoa Range area (J31, K29, K30, K31, K32, L29, and L 30 in Fig. 2), but S. cresswelli was collected only once in>100 years of collecting. Twenty-five collection events are reported from the Lewis Pass area (map sheet L 31 in Fig. 2) and>80 from Arthur’s Pass (map sheet K33). On current distribution records, this snail appears to be sparse. We recommend ranking S. cresswelli as ‘At Risk: Naturally Uncommon’, with the qualifiers ‘Data Poor: Size and Trend’ and ‘Biologically Sparse’. The 2010 NZTCS assessment ranked S. cresswelli as ‘Insufficient information: Data Deficient’, with the qualifier ‘Biologically Sparse’.