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

( Figs 16, 23C, 26, 44)

Sinployea ‘parvaformis’ McGuinness 2001: 595; Hitchmough 2002:130.

Charopidae sp. 108 (NMNZ M.076163) Hitchmough et al. 2007: 131; Spencer et al. 2009: 216; Mahlfeld et al. 2012: appendix 1.

Charopidae sp. 35 (NMNZ M.103006) Hitchmough et al. 2007: 59; Spencer et al. 2009: 216; Mahlfeld et al. 2012: appendix 1.

Material examined: New Zealand, North Island , Hauraki Gulf , Coromandel Peninsula , N of Katikati, Karangahake Gorge, steep cliff area by river, in soil sieved from under fallen treefern fronds, 37°27′28.079″S, 175°54′16.907″E, D.J. Roscoe, 26 December 1979, NMNZ: M.103006, holotype ( Figs 23C, 26) ; M.115996, paratypes.

Other material examined: New Zealand, North Island, NMNZ: Hauraki Gulf, Coromandel Peninsula : M.115993, Port Jackson , 36°28′29.234″S, 175°21′05.541″E, B.F. Hazelwood and J.F. Goulstone, 1978, subfossil in dunes at mouth of Muriwai stream; M.076163, M.115992, and M.194413, SE of Whitianga , Hot Water Beach , 36°53′14.827″S, 175°49′15.310″E, P.C. Mayhill, May 1981 ; Bay of Plenty: M.186830, S of Opotiki, Waioeka-Opotiki Domain , 38°04′51.930″S, 177°18′39.217″E, P.C. Mayhill, July 1991 .

Description: Shell small, thin, and fragile, 2.4 mm wide and 1.28 mm high at 3.1 whorls, moderately finely ribbed, loosely coiled, narrowly umbilicate, spire weakly elevated. Shell with translucent pale buff background and equidistant, narrow, brown zigzag axial bands, which taper and fade out on the shell base, leaving a lighter patch surrounding the umbilicus. Spire broad, weakly domed. Protoconch of 1.25 convex whorls, translucent, 591 μm wide; sculpture consisting of seven to eight thin, crisp, widely spaced spiral lirae. Teleoconch of ~1.8 rapidly expanding, convex whorls, slightly flattened ab- and adaxially. Sculpture consisting of numerous calcareous, thin, primary axials traversed by fine spiral lirae; spirals approximately one-third of the width of primary axials and forming microscopic beads at intersections with even finer secondary axials, about seven to nine axials per

Sinployea systematics and biogeography • 35 interspace. Primary axials crested with a short, fine periostracal lamella, often worn off (56 axials on first teleoconch whorl). Umbilicus 606 μm wide (D/U ratio 3.96); relatively large for this taxonomic group. Suture deep. Aperture obliquely oval; columella short and a little curved and reflected, partly covering umbilicus; outer lip simple.

Reproductive anatomy: Unknown.

Etymology: After Karangahake Gorge, Coromandel Peninsula, northern North Island.

Distribution: Coromandel Peninsula and eastern Bay of Plenty.

Ecology: Subtropical coastal mixed broadleaf forest–shrubland.

Related species: Sinployea karangahake is distinguished from other NZ Sinployea by the large shell and protoconch, the relatively coarsely ribbed teleoconch with axial colour bands (sometimes more irregular) that fade out on the shell base, and a moderately wide umbilicus. The shell collected from near Hotwater Beach has more regular axial colour bands than those of the type. More observations in the field and shells are needed to understand variation in this species better .

Conservation status: Sinployea karangahake is known from Coromandel Peninsula and south of Opotiki, Bay of Plenty. It has not been recollected since the 1980s. The 2010 NZTCS assessment ranked this species ‘At Risk: Naturally Uncommon’, with the qualifier ‘Biologically Sparse’. We suggest adding the qualifiers ‘Data Poor: Size and Trend’ because of the considerable time that has elapsed since the species was last found. Dune or midden surveys could also help to determine whether the distributional range has contracted since human occupation. If so, a change to ‘At Risk: Relict’ would be required.

Sinployea imperforata Climo, Mahlfeld & Roscoe sp. nov.

( Figs 16, 27A, 28, 44)

Charopidae sp. 33 (NZMN M.085221) Hitchmough et al. 2007: 59; Spencer et al. 2009: 216; Mahlfeld et al. 2012: appendix 1.

Material examined: New Zealand, North Island : NMNZ M.085221, holotype ( Figs 27A, 28), SW of Mangakino , Pureora Forest Park, 60% logged area, 38°30′08.488″S, 175°35′08.228″E, P.C. Mayhill, November 1981 ; MA85882 , paratype, SE

Sinployea systematics and biogeography • 37

Auckland, Hunua Ranges, Mangatawhiri , 37°06′09.608″S, 175°09′10.887″E, J.F. Goulstone, October 1985 .

Other material examined: New Zealand, North Island , NMNZ: M.088060, Coromandel Peninsula , NE of Thames, Table Mountain , 37°02′44.783″S, 175°39′10.275″E, J.F. Goulstone, 1977; M.088059 , SE of Auckland, Mangatawhiri River Valley , 37°06′15.615″S, 175°09′35.380″E, J.F. Goulstone, 1977 .

Description: Shell small, depressed subglobose, thin, and fragile, ~ 2.1 mm wide and ~ 1.2 mm high at ~2.6 whorls, finely ribbed, loosely coiled with a silky sheen. Spire moderately elevated; umbilicus closed. Colour brown with narrow irregular bands and small patches of white that originate near the suture and fade on the shell base, which is chiefly brown. Protoconch of 1.25 convex whorls, translucent brown, 573 μm wide, sculptured with six to seven spiral lirae. Teleoconch of 1.35 rapidly expanding, convex whorls with a slightly flattened base. Sculpture consisting of numerous, thin, primary axials traversed by fine spiral lirae (106 axials on first teleoconch whorl); spirals approximately half the width of primary axials and forming microscopic beads at intersections with very fine secondary axials, about four to five per interstitial space. Each primary axial is crested with a very fine periostracal lamella, often worn off. Suture deep. Aperture oblique, squarish; columella a little reflected, lip simple.

Reproductive anatomy: Unknown.

Etymology: From Latin, in ‘not’ and perforare ‘to bore through’, referring to the shell character of closed umbilicus.

Distribution: New Zealand, North Island, Northland: Kaipara; SE Auckland: Hunua, Mangatawhiri; Waikato: Pureora; Coromandel Peninsula: NE of Thames, Table Mountain.

Ecology: Lowland to montane subtropical mixed podocarp– broadleaf forest.

Related species: Sinployea imperforata is the only NZ species of the genus with a closed umbilicus and chiefly brown shell colour with small irregular, pale buff streaks and high rib count.

Conservation status: Altogether, 16 collections of this species are listed in Te Papa’s database, in comparison to>700 collection events listed from Auckland (R 11 in Fig. 2). This species is rarely detected in leaf litter samples from Kaipara to Pureora Forest and might also live in Kaimai Range. Kaimai records were not analysed, but there is a record in Te Papa database from NE of Matamata, which would extend records south of the Coromandel distribution. The current ranking is ‘At Risk: Naturally Uncommon’, with the qualifiers ‘Data Poor: Size and Trend’ and ‘Biologically Sparse’. No change in threat ranking is proposed for S. imperforata .