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

( Figs 16, 33A, 34, 45)

Charopidae sp. 182 (NMNZ M.106365) Hitchmough et al. 2007: 131; Mahlfeld et al. 2012: appendix 1.

Material examined: New Zealand, South Island, SE of Nelson, Bryant Range, 2 m within Maitai Cave , 41°19′17.238″S, 173°21′04.776″E, D.J. Roscoe, 5 January 1982, NMNZ: M.106365, holotype ( Figs 33A, 34) ; M.115989, paratype.

Other material: New Zealand, South Island , SSE and SE Nelson, NMNZ: M.108549, Richmond Range, The Doubles Track ,

44 • Mahlfeld et al.

41°17′16.740″S, 173°23′56.055″E, D.J. Roscoe, 4 August 1985; M.108696, S of Wakefield, Wairoa Gorge, Pig Valley , in open bush , 41°27′22.059″S, 173°03′44.571″E, D.J. Roscoe, 2 July 1985.

Description: Shell small, depressed subglobose, thin, and fragile, 3.6 mm wide and 1.3 mm high at four whorls, coarsely ribbed and moderately tightly coiled for the group. Spire broadly domed, 320 μm high, apex only slightly emergent. Umbilicus moderately wide, 680 μm in diameter (D/U ratio 5.29). Shell translucent white. Protoconch large for the group (669 μm wide), with 1.75 convex whorls, sculptured with four very fine and very widely spaced spiral lirae. Teleoconch of ~2.25 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 secondary axials and form microscopic beads at the intersections with secondary axials, ~8–11 axials per interstitial space. Primary axials (51 on first teleoconch whorl) have a rounded ridge, periostracal lamella absent. Suture shallower than in other Sinployea species and not as steep sided. Aperture round, outer lip simple. Columella slightly oblique and hardly reflected.

Reproductive anatomy: Unknown.

Etymology: The species is named after Maitai Cave, Bryant Range, Nelson.

Distribution: South Island, Nelson, Richmond, and Bryant Ranges.

Ecology: Unknown.

Related species: The combination of relatively tight coiling, moderately wide umbilicus, translucent white shell, and coarsely ribbed teleoconch, sculptured with sturdy riblets, distinguishes S. maitai from other NZ species of Sinployea . On its shell features and in its geography, S. maitai sits between Climocella and the tightly coiled southern species of Sinployea described below, and the more loosely coiled northern NZ species of Sinployea . The shell architecture is similar to the Cook Islands species.

Conservation status: The known range of S. maitai spans a distance of ~ 35 km along the western edge of the Richmond State Forest Park. More than 70 collection events are recorded from map sheet N28, which includes Wairoa Gorge based on Te Papa collection records, but only one sample from Pig Valley contained S. maitai . Of the 60 collection events from the Bryant Range, 32 are from Maitai Valley and 27 from Maitai Cave, but only 2 samples contained shells of S. maitai . In total, 114 samples are recorded in Te Papa terrestrial molluscs collection from O27 ( Fig. 2). It is likely that S. maitai is a western Richmond Range/Bryant Range endemic, and therefore we suggest ranking this species as ‘At Risk: Naturally Uncommon’, with the qualifiers ‘Data Poor: Size and Trend’ and ‘Biologically Sparse’ until new information becomes available. This species has not been collected by us since the mid-1980s. The 2010 NZTCS assessment ranked this species as ‘At Risk: Naturally Uncommon’, with the qualifier ‘RR’ (Range Restricted).