Sinployea canaliculata 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 canaliculata Climo, Mahlfeld & Roscoe sp. nov.

( Figs 16, 37A, 38, 45) Vicariodiscus ‘canaliculatus’ McGuinness 2001: 596; Hitchmough 2002: 130.

Charopidae sp. 49 (NMNZ M.113791) Hitchmough et al. 2007: 83; Spencer et al. 2009: 213; Mahlfeld et al. 2012: appendix 1.

Material examined: New Zealand, South Island : CM 2021.85.1, holotype ( Fig. 38), S Westland, bush edge at S end of the flats immediately upvalley from confluence of Donald and Waiatoto Rivers, 44°14′06.729″S, 168°46′28.714″E, I.J. Payton, 20–21 January 1973 ; NMNZ M.113791, paratype ( Fig. 37A), Fiordland, Stella Falls , SE of Deep Cove, Doubtful Sound 45°29′00.256″S, 167°11′16.323″E, P.C. Mayhill, February 1985 .

Other material examined: New Zealand, South Island, Fiordland, NMNZ: M.082788, Stella Falls, Doubtful Sound, SE of Deep Cove, 45°29′00.256″S, 167°11′16.323″E, P.C. Mayhill, February 1985; M.085625, SW of Manapouri, Borland Saddle, 45°44′47.821″S, 167°23′11.600″E, P.C. Mayhill, February 1986; M.085027, WSW of Manapouri, Centre Pass, Dusky Track, 45°36′00.744″S, 167°08′33.399″E, P.C. Mayhill, February 1986; Otago: M.082985, NW of Queenstown, Routeburn Track, Key Summit, 44°48′42.095″S, 168°07′40.236″E, P.C. Mayhill, February 1985; M.116773, Double Barrel Track, 44°43′16.270″S, 168°16′14.409″E, P.C. Mayhill, January 1989; Westland: M.157314, W of Lake Moeraki, NE of Haast, Roadside, 43°43′24.068″S, 169°14′12.943″E, P.C. Mayhill, January 1992; M.113792, Waiatoto River Valley, near Donald Hut, 44°04′33.988″S, 168°51′34.938″E, O.J. Marston, 20 January 1973; SW of Westport, NE of Charleston, 40 m a.s.l., 41°53′03.230″S, 171°28′07.380″E, F.M. Climo, 23 December 1992. Sphagnum (Ehrh.) Hedw. under regrowth rimu ( Dacrydium cupressinum ; record from research notes, not re-examined).

Description: Shell small, depressed subglobose, thin, and fragile, 1.7 mm wide and 0.98 mm high at 3.75 whorls, coarsely ribbed and moderately tightly coiled for the group. Spire broadly domed, 256 μm high, apex emergent. Umbilicus moderately wide, 609 μm in diameter (D/U ratio 2.79). Shell chiefly bronze brown, with a few narrow translucent white axial bands, which taper towards the umbilicus. Protoconch 507 μm wide, with 1.5 convex whorls, sculptured with seven to eight spiral lirae. Teleoconch of 1.75 steadily expanding, convex whorls with a round base. Sculpture consisting of sturdy, weakly protractive primary axials traversed by narrowly spaced fine spiral lirae. These spiral cords are about twice the width of secondary axials and form microscopic beads at the intersections with secondary axials, ~8–10 axials per interstitial space. Primary axials (~55 on first teleoconch whorl) have a narrow, rounded ridge, crested with a short periostracal lamella (usually worn off). Suture is channelled, and the sutural slope is steep. Aperture ~724 μm high, round, outer lip simple. Columella short, vertical, not reflected.

Reproductive anatomy: Unknown.

Etymology: From Latin canaliculatus, in reference to the shell character of channelled suture.

Distribution: South Island, Westland: NE of Charleston; near Lake Moeraki and Waiatoto Valley; NW Otago, Routeburn: Key Summit and Double Barrel Track; Fiordland: Stella Falls near Doubtful Sound; Borland Saddle and Centre Pass near Manapouri.

Ecology: Temperate beech ( Nothofagus ) forest and in Sphagnum under regrowth rimu ( Dacrydium cupressinum ).

Related species: Sinployea canaliculata is the only NZ Sinployea species with a canaliculate suture. Interestingly, other species of New Zealand land snails with canaliculate sutures occur predominantly in western South Island, e.g. species of Canallodiscus Marshall & Barker, 2008, Ptychodon Ancey, 1888 , and Huonodon Iredale, 1945 from Fiordland, Westland, and Nelson. Sinployea proxima is the only Polynesian species in the genus with a channelled suture.

Conservation status: This species was first collected by I. Payton and J. Marston from the Waiatoto Valley, S Westland in 1973. All the remaining records listed here are based on collections by P. Mayhill in the 1980s and one in 1992 from W of Lake Moeraki, near Haast, S Westland. One of the authors collected S. canaliculata from NE of Charleston, N Westland in 1992. We recommend continuing to rank S. canaliculata as ‘At Risk: Naturally Uncommon’, with the qualifiers of ‘Data Poor: Size and Trend’ and ‘Biologically Sparse’.

Sinployea charopiformis Climo, Mahlfeld & Roscoe sp. nov.

( Figs 16, 37B, 39, 45) Vicariodiscus ‘charopiformis’ McGuinness 2001: 595; Hitchmough 2002: 130.

Charopidae sp. 48 (NMNZ M.025033) Hitchmough et al. 2007: 131; Spencer et al. 2009: 213; Mahlfeld et al. 2012: appendix 1.

Material examined: South Island , Fiordland , Caswell Sound head, Stillwater River, 45°02′40.744″S, 167°19′33.804″E , R.K.

Dell, 13 March 1949, NMNZ: M.025033, holotype ( Figs 37B, 39) ; M.113793, paratype.

Other material examined: South Island , Westland: Punakaiki, 42°06′52.286″S, 171°19′39.619″E, D.J. Roscoe, 14 May 1994 (Roscoe collection) .

Description: Shell small, depressed subglobose, thin, and fragile, 1.6 mm wide and 0.9 mm high at 3.5 whorls, coarsely ribbed and moderately tightly coiled for the group. Spire broadly domed, 233 μm high, apex only slightly emergent. Umbilicus moderately wide, 544 μm in diameter (D/U ratio 2.94). Shell chiefly bronze brown, with a few narrow translucent white axial bands, which taper towards the umbilicus. Protoconch 527 μm wide with 1.75 convex whorls, sculptured by spiral lirae but these not clear enough to be counted confidently. Teleoconch of 1.75 steadily expanding, convex whorls, with a round base. Sculpture consisting of sturdy primary axials traversed by narrowly spaced fine spiral lirae. These spiral cords about twice the width of secondary axials and forming microscopic beads at the intersections with secondary axials, ~8–10 axials per interstitial space. Primary axials (~62 on first teleoconch whorl) with a narrow, rounded ridge, crested with a short periostracal lamella but worn off. Suture deep and sutural slope relatively steep, as in S. waipoua , S. kaipara , S. haupatoto , and S. mangamuka . Aperture ~667 μm high, round, outer lip simple. Columella short and slightly oblique, not reflected.

Reproductive anatomy: Unknown.

Etymology: Named for its charopine-like shell architecture, sculpture, and shell colour pattern.

Distribution: South Island, N Westland and Fiordland.

Ecology: Temperate beech ( Nothofagus ) forest.

Related species: Sinployea charopiformis has a more finely ribbed teleoconch, a smaller umbilical width, and a smaller embryonic shell than S. cresswelli , and it lacks the channelled suture of S. canaliculata .

Conservation status: This species is known from only two disjunct localities, 460 km apart, in N Westland (Punakaiki) and Fiordland (Stillwater River, Caswell Sound). Similar disjunct distributions involving Nelson /Westland and Fiordland have been documented before for terrestrial gastropods and many other animals and plants ( Climo and Mahlfeld 2011, Heads 2017). The Fiordland area has not been surveyed very comprehensively for land snails ( Fig. 2). However,>140 sampling events in N Westland around Punakaiki (K 30 in Fig. 2), have produced one record (collected in 1994) of S. charopiformis . We are aware of only 21 collection events from the Caswell Sounds area in Fiordland (C 42 in Fig. 2), and only one sample collected by R.K. Dell in 1949 produced a record for the species. We recommend continuing with a ranking of ‘At Risk: Naturally Uncommon’, with the qualifiers of ‘Data Poor: Size and Trend’ and ‘Biologically Sparse’. The 2010 NZTCS assessment ranked S. charopiformis as ‘At Risk: Naturally Uncommon’, ‘Data Poor’, and ‘Biologically Sparse’.