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

( Figs 16, 23B, 25, 44)

Sinployea ‘Kaukapakapa’ McGuinness 2001: 594; Hitchmough 2002: 130.

Charopidae sp.26 (NMNZ M.082966) Hitchmough et al. 2007: 128; Spencer et al. 2009: 216; Mahlfeld et al. 2012: appendix 1.

Charopidae sp. 36 (NMNZ M.075729) Spencer et al. 2009: 216; Mahlfeld et al. 2012: appendix 1.

Material examined: New Zealand, North Island , Northland, NMNZ: M.082966, holotype ( Figs 23B, 25), Kaipara Harbour, Okahukura Peninsula, beside Burma Road , 36°21′48.549″S, 174°19′53.443″, P.C. Mayhill, September 1985 ; paratype, M.075729, Kaipara Flats, Thomson Kauri Grove Scenic Reserve , 36°21′48.341″S, 174°20′09.485″E, B.F. Hazelwood, 28 September 1983 .

Other material: Known only from type material.

Description: Shell small, thin, and fragile, 2.2 mm wide and 1.22 mm high at three whorls, moderately finely ribbed, loosely coiled, narrowly umbilicate and low spired (spire 250 μm high). Colour pattern of relatively broad, brown axial colour bands on whitish translucent background, colour bands forming zigzags along shell periphery and merging into a large patch on shell base. Protoconch of 1.25 convex whorls, translucent, 556 μm wide, sculptured with five to six thin, crisp, widely spaced spiral lirae. Teleoconch of 1.75 rapidly expanding, convex whorls, base slightly flattened. Sculpture consisting of relatively narrowly spaced primary axials (~67 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, about five axials per interspace. Each primary axial crested with a very fine periostracal lamella, often worn off. Umbilicus is moderately narrow, 494 μm wide (D/U ratio 4.45); partly covered by reflected columella. Aperture (975 μm high) obliquely round, slightly more angular towards columella and laterally expanded, lip simple. Suture deep.

Reproductive anatomy: Unknown.

Etymology: After Kaipara district, north of Auckland.

Distribution: Sinployea kaipara is known only from two sites north of Auckland, which are ~ 20 km apart. Considering the distributions of the other Sinployea species in the Northland and Auckland area, it is likely that S. kaipara is restricted to the Kaipara area.

Ecology: Sinployea kaipara is known only from forests dominated by kauri ( Agathis australis (D.Don) Lindl. ex Loudon ).

Related species: The combination of a finely ribbed shell with large brown flammulations and brown base is also found in S. waipoua (larger protoconch) and S. haupatoto . Sinployea solemi and S. haupatoto have smaller protoconchs and umbilical diameters and greater whorl expansion than S. kaipara . The more ‘blocky’ colour pattern of S. kaipara is similar to that of Calymna costulata .

Conservation status: North Island collections of land snails are shown in Figure 2; only two of those have produced shells of S. kaipara . The species has not been re-collected since the mid-1980s. A collecting trip made by K.M. and D.J.R. in kauri forest near Kaukapakapa in September 2015 was not successful in detecting this species. There is no information available on population size or trend. Most northern NZ Sinployea species occur in very low numbers and are rarely collected, and it appears that this species occurs in low numbers at few localities in the Kaipara area. Any impact of the current kauri dieback (caused by Phytophthora agathidicida ) on land snail diversity and on this particular species is unknown. It is 37 years since the species was last found. Because it was not collected in any of the other samples taken from the area, and because many Sinployea species are allopatric, it seems most likely that this species occurs in a few small, scattered populations and is a naturally uncommon Kaipara endemic. The last assessment (2010 NZTCS panel meeting; Mahlfeld et al. 2012) ranked this species as ‘Data Deficient’, with the qualifier ‘one locality’ (OL). A change in ranking from ‘Data Deficient’ to ‘Naturally Uncommon’, with the qualifiers ‘Data Poor: Size and Trend’ and ‘Biologically Sparse’, is therefore proposed here. A further change to ‘Nationally Critical’ might follow, if further surveys fail to detect this species.