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

( Figs 16, 19C, 22, 44) Sinployea ‘mangamuka’ McGuinness 2001: 595; Hitchmough 2002: 130.

Charopidae sp. 32 (NZMN M.062484) Spencer et al. 2009: 216; Mahlfeld et al. 2012: appendix 1.

Material examined: New Zealand, North Island, Northland, NMNZ: M.062484, holotype ( Fig. 22), ESE of Kaitaia, WNW of Mangamuka, Soda Springs Track , 35°11′53.601″S, 173°29′02.766″E, P.C. Mayhill, October 1978 .

Other material examined: New Zealand, North Island, Northland, NMNZ: M.082837, ESE of Kaitaia, Mangamuka Gorge Walkway , summit, 35°10′55.496″S, 173°28′14.806″E, P.C. Mayhill, April 1983 ; M.062483, Mangamuka Ranges , The Saddle, C. Dawber, August 1978 ; M.096636, between Kaikohe and Moerewa, Pouerua Bush , 35°23′05.302″S, 173°55′49.540″E, G.R. Parrish, 27 August 1987 ; M.079406, Hauraki Gulf, Little Barrier Island, E of Te Toki Point , Tirikawa Stream , 36°12′55.960″S, 175°04′05.680″E, P.C. Mayhill, August 1983 .

Description: Shell small, depressed subglobose, thin, and fragile, 2.3 mm wide and 1.28 mm high at three whorls, moderately coarsely ribbed and moderately loosely coiled for the group. Spire flat, but bulbous apex a little emergent; umbilicus narrow, 461 μm wide (D/U ratio 4.99). Shell colour is mostly brown all over except for dorsal patches of translucent white, which reach the periphery but fade rapidly on the shell base, which is chiefly brown. Protoconch of 1.25 convex whorls, 594 μm wide, sculptured with seven thin spiral cords. Teleoconch of 1.75 steadily expanding, convex whorls with a rounded base. Sculpture consisting of slightly more sinuous, thin 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, about five to seven axials per interstitial space. Primary axials (~49 on first teleoconch whorl), each crested with a very fine periostracal lamella (often worn off). Suture is deep. Aperture oblique, laterally expanded, outer lip simple. Columella is short and reflected.

Reproductive anatomy: Unknown.

Etymology: After Mangamuka, Northland.

Distribution: New Zealand, Northland, Mangamuka Gorge and Pouerua (12 km SE of Kaikohe); Hauraki Gulf, Little Barrier Island.

Ecology: Subtropical mixed podocarp–broadleaf forest.

Related species: The combination of relatively compact squarish shell architecture (shell height 1.28 mm), brown shell colour with few light patches dorsally and brown base, flat spire with a weakly emergent, bulbous apex, relatively coarsely ribbed teleoconch, and more sinuous axials distinguish S. mangamuka from other NZ Sinployea species. Sinployea kaipara , of similar shell architecture and colour pattern, has a higher rib count.

Conservation status: The three localities this species is known from are flanked by allopatric species of Sinployea ( Fig. 16). The Mangamuka Gorge locality is ~ 55 km from Pouerua Bush and ~ 200 km from Little Barrier Island. The last collection of the species was in 1987 at Pouerua Bush. Based on the collection data, it seems likely that S. mangamuka is a central Northland endemic wedged between the distributions of S. waipoua and snails that are likely to be conspecific with S. solemi . The 2010 NZTCS assessment did not rank S. mangamuka . We suggest a new listing of ‘At Risk’, ‘Naturally Uncommon’, with the qualifiers ‘Data Poor: Population Size and Trend’ and ‘Biologically Sparse’.