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

( Figs 16, 27B, 30, 44) Sinployea ‘Hikurangi’ McGuinness 2001: 594.

Charopidae sp. 106 (NMNZ M.076803) Hitchmough et al. 2007: 60; Spencer et al. 2009: 216; Mahlfeld et al. 2012: appendix 1.

Material examined: New Zealand, North Island , East Cape, NMNZ: M.076803, holotype ( Figs 27B, 30), Mount Hikurangi, 1300 m a.s.l., 37°54′21.802″S, 178°03′26.852″E, P.C. Mayhill, November 1980 ; E Hauraki Gulf, Coromandel Peninsula : paratype, M.076241, SW of Whitianga , Tairua , Charlotte’s Farm, beside track to Tapuaetahi trig, 36°35′03.118″S, 175°15′00.335″E, P.C. Mayhill, April 1981 .

Other material examined: New Zealand, North Island, NMNZ: M.078851, East Coast, NE of Gisborne, Tokomaru Bay , TV translator access road, 38°08′36.948″S, 178°18′38.911″E, F.M. Climo, 18 May 1983; M.191196, Coromandel Peninsula, N of Tairua , Cupps Road , Wallace farm, 36°54′51.378″S, 175°49′47.417″E, P.C. Mayhill, May 1981; Hawke’s Bay: 5 km E of Lake Waikaremoana, Ngamoko Trig , station 6, mainly large leaved beech litter, S. Elia ( Department of Conservation ), February 2015 (Open Lab collection) .

Description: Shell small, thin, and fragile, 2.3 mm wide and 1.24 mm high at 3.4 whorls, coarsely ribbed, loosely coiled, narrowly umbilicate. Spire broadly flat, hardly elevated. Shells are uniformly light bronze. Protoconch of 1.2 convex whorls, translucent, 494 μm wide, sculptured with five to six thin, widely spaced spiral lirae. Teleoconch of 2.2 rapidly expanding, convex whorls, base slightly flattened. Sculpture consisting of relatively widely spaced primary axials (~37 on first postnuclear whorl). Axials traversed by fine spiral lirae; spirals approximately one-third of the width of primary axials and forming microscopic beads at intersections with secondary axials, ~10 axials per interspace. Primary axials crested with a very fine periostracal lamella, often worn off. Umbilicus moderately wide, 541 μm wide (D/U ratio 4.25); columella only slightly reflected. Aperture (975 μm high) obliquely lunate, columella subangled; lip simple. Suture deep.

Reproductive anatomy: Unknown.

Etymology: Named after Mount Hikurangi, Raukumara Range, East Cape.

Distribution: New Zealand, North Island: Eastern Coromandel Peninsula, eastern Bay of Plenty, East Coast and northern Hawke’sBay.

Ecology: Subtropical coastal to montane broadleaf forest.

Related species: Sinployea hikurangi is most similar to S. accelerata , but the shells of the latter species are unicoloured pale buff. Sinployea capensis snails have more coarsely ribbed teleoconchs and are unicoloured pale buff.

Conservation status: Sinployea hikurangi is known from Tairua, Coromandel, and the Raukumara and Ngamoko Ranges. The East Coast ranges have not been widely collected because of the steep terrain and difficult access. However, considering the mostly allopatric distributions of the other Sinployea species, it is likely that S. hikurangi is a Coromandel Peninsula–East Coast endemic. The 2010 NZTCS assessment ranked this species as ‘At Risk: Naturally Uncommon’, with the qualifiers ‘Data Poor’ and ‘Biologically Sparse’. No change is required except for modifying the qualifiers to ‘Data Poor: Size and Trend’.