Sinployea Solem, 1983

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) : -

Genus Sinployea Solem, 1983

Type species: Sinployea peasei Solem, 1983 .

Figure 10 shows a photograph of the paratype from the Auckland Museum collections.

Remarks: Solem (1983) described the new genus Sinployea (an anagram of Polynesia) and included species from Micronesia (Saipan, northern Marshall Islands) to SE Polynesia (Rarotonga, French Polynesia). Subsequently, Brook (2010) described four additional Sinployea species from Rarotonga ( Sinployea muri Brook, 2010 ; Sinployea taipara Brook, 2010 ; Sinployea titikaveka Brook, 2010 ; and Sinployea tupapa Brook, 2010 ). Stanisic et al. (2010) adopted Sinployea for the Australian Sinployea intensa ( Iredale, 1941) and Sinployea intermedia ( Odhner, 1917) , turning Sinployea intermedia Solem, 1983 from Swains Island, Tokelau into a homonym.

Pacific Island Sinployea Solem, 1983 includes small- to medium-sized charopid snails with a shell diameter of ≤ 6 mm at 5.25 whorls and an embryonic sculpture of 9 (rarely fewer), often 10–12, and no more than 18–20, prominent fine spiral lirae. The lirae of S. peasei , the type of Sinployea , are shown in Figures 10 and 11. The axial teleoconch sculpture of Sinployea species ranges from irregular to well-defined ribs that are widely to closely spaced and are weakly to strongly protractively sinuous. The microsculpture consists of finer spirals and axials with beading at intersections. The shell colour patterning varies from brown flammulations to unicoloured light horn to dark reddish brown. Whorls of most species have a rounded periphery. Shell coiling ranges from somewhat tightly to loosely coiled, and sutures are deep, except for Sinployea proxima (Garret, 1872) of the Cook Islands (Rarotonga), which has a channelled suture. The spire ranges from flat to moderately elevated, and umbilical shape and width are also variable among species. Solem (1983) provides comprehensive shell measurements and discussion regarding variation in shell architecture and sculpture.

NZ Sinployea species have a shell diameter of ≤ 3.6 mm at 2.25 whorls and protoconchs with usually five to eight spiral lirae, although one species has 14 ( Fig. 11). Teleoconch sculpture consists of primary and secondary axial ribs and spiral cords as in the Polynesian, Micronesian, and Melanesian species. Sinployea capensis and S. accelerata each possess a basal glandular appendage that joins the penial duct through a papilla, whereas in Calymna costulata the appendage enters the penial atrium through a simple opening ( Figs 4, 6). Pacific Island Sinployea species have pocket pilasters. The northern NZ Sinployea species are more loosely coiled than the southern species. On shell architecture, the South Island Sinployea fiordlandica and Sinployea australis are closer to the North Island species. Most species have narrowly umbilicate shells, except for the anomphalous S. imperforata and South Island Sinployea charopiformis , Sinployea cresswelli , and Sinployea canaliculata , which have a wider umbilicus. Shells are either colour-patterned or are unicoloured ( Table 1). The northern NZ species and the southern South Island S. fiordlandica and S. australis are architecturally similar to the Tongan species, whereas the other southern NZ species are similar to the more tightly coiled Rarotongan species.

The embryonic sculpture of some Flammoconcha species approaches the spiral sculpture of Calymna protoconchs, but the teleoconch sculptures are very different. Flammoconcha species do not have the charopine reticulate sculpture with beading at the intersections of spirals and axials. Figure 12 depicts the conchological differences between Flammoconcha and Calymna . Figures 11 and 13 illustrate the spirally lirate protoconch sculpture of Sinployea and the spirally corrugate Calymna embryonic shell sculpture. The shell and reproductive morphology of Flammulina jacquenetta combines a range of characters, which lean towards Sinployea , Calymna , and Flammoconcha morphologies: diagonal, grid-like shell sculpture like Flammoconcha stewartensis on the protoconch and teleoconch; and low axial ridges cut by a delicate, approximately rectangular, grid of grooves on the teleoconch ( Fig. 14). The way species of Sinployea , Calymna , Flammoconcha , and Flammulina share and recombine characters suggests to us that any future revision should consider them together.

Notes on intergeneric relationships: Calymna (Tasmania and NZ), Flammoconcha (NZ) , Tuimalila Solem, 1983 ( Tonga), Vatusila Solem, 1983 ( Marshall Islands, Lau, Tonga, Niue, and Tuvalu), Sinployea (Melanesia, Polynesia, and NZ) Climocella Goulstone, 1996 ( NZ), Allodiscus s.l. species ( NZ), Beilania Preston, 1913 ( Philippines, Belau?, Sarawak, Indonesia, Moluccas,andpossibly, NZ), Lagivala Solem, 1983 ( Indonesia to Lau and Tuvalu) and some Andrefancia Solem, 1960 ( New Caledonia) constitute a broad band of charopid species with spiral protoconch sculptures mainly peripheral to the Australian continent, as described by Stanisic (1990) and Holcroft (2018).

Within this geographical band of spiral protoconch sculpture exists a further division between male genitalia with a glandular appendage found in Tasmanian/ NZ Calymna and NZ Flammoconcha and Sinployea species to reduced male genitalia without an appendage found in some NZ Calymna and Pacific Islands Sinployea , which sometimes have a pocket pilaster ( Figs 3–9). The regional extent of this pattern suggests an evolutionary history that evolved in tandem with the geology of the region, which are the reorganization of the eastern Gondwana margin and the development of the Cenozoic plate boundary between the Indo-Australian and Pacific plates.

Notes on distributions: Species diversity increases from west to east through the Pacific ( Fig. 15). Fiji, New Zealand, and the Cook Islands are the main hotspots. Currently, 71 species are described from the following localities: Mariana Islands, Saipan (1 species, possibly introduced), Caroline Islands (1), New Britain (2), NE Australia (2), Solomon Islands (3), Vanuatu (1), Tuvalu (2), Rotuma (1), Fiji (11), Tonga (3, one of which is also on Futuna Island), NZ (17), Swains Island (in the Tokelau group) (1), Samoan archipelago (6), Cook Islands (17), and French Polynesia (6). Most of the species are endemic to one island group ( Solem 1983: 50; Brook 2010, Rundell and Czekanski-Moir 2015, Holcroft 2018, Bullis and Rundell 2021, and the present paper). We have not seen material of Sinployea pitcairnensis Preece, 1995 , from Pitcairn Island. Sinployea conica (Odhner, 1922) from Juan Fernández Islands, Chile, is most likely to be a member of Punctidae , not Charopidae (auth. obs.).

Notes on distributions of NZ species: The distributions of northern and southern groups are connected geographically via the distributions of S. accelerata ( Fig. 16) and Climocella prestoni ( Sykes, 1895) , which occurs from central to lower North Island and northern South Island. Climocella species are distinct from Sinployea by axials encroaching on the spirally lirate protoconch ( Fig. 17).

Sinployea olohega Climo, Mahlfeld & Roscoe sp. nov.

Sinployea intermedia Solem, 1983: 131 .

Remarks: We introduce this name as a replacement for Solem’s species, which is a junior homonym of Sinployea intermedia ( Odhner, 1917) . Olohega is the Tokelauan name for Swains Island.