Charopa cassandra Hutton, 1883

Brook, Fred J., Kennedy, Martyn, King, Tania M., Ridden, Johnathon, Shaw, Matthew D. & Spencer, Hamish G., 2020, Catalogue of New Zealand land, freshwater and estuarine molluscan taxa named by Frederick Wollaston Hutton between 1879 and 1904, Zootaxa 4865 (1), pp. 1-73 : 22-23

Charopa cassandra Hutton, 1883

Pl. 2, fig. C

Hutton, 1883. New Zealand Journal of Science, 1: 476.

Type material. In Canterbury Museum, Christchurch, according to Suter (1913: 638), overlooked and reported as missing by Freeman et al. (1997: 36), but one specimen rediscovered in 2017. Lectotype (designated here), CMNZ M240 (dry shell).

Label details. ‘Napier (56.), Hutton coll.’.

CMNZ molluscan catalogue details. M240—‘ Allodiscus cassandra Hutton, Napier (1 specimen) (old No. 56) ’.

Type locality. Cited as ‘Napier’ by Hutton (1883g: 477, 1884b: 182, 1884c: 201), but this is an error (see below).

Previous illustrations of type material. Pilsbry (1892 [in 1892–1893]: 67, pl. 22, figs. 37–39—‘drawn from Prof. Hutton’s type’, ‘H. Suter, del.’), Suter (1915: pl. 9, figs. 2, a, b—probably the same shell as illustrated by Pilsbry).

Remarks. Hutton (1884b: 182) noted that “The only specimens I have seen were old and rubbed”, which suggests that the type material originally may have consisted of more than one specimen. He recorded the locality as Napier but did not state who had collected the type material. Hutton submitted a description of this species to the Transactions and Proceedings of the New Zealand Institute issue for 1883, but publication was delayed until May 1884 ( Hutton 1884b: 181), and was pre-empted by a brief description in an account of a meeting of the Philosophical Institute of Canterbury ( Hutton 1883g: 476). There has been confusion over the identity and distribution of this species. It was tentatively assigned to Charopa Albers, 1860 by Hutton (1884b: 181), transferred to Psyra Hutton,1883 by Hutton (1884c: 201), and included in Allodiscus Pilsbry, 1892 by Pilsbry (1892 [in 1892– 1893]: 66, pl. 22, figs. 37–39) and subsequent authors. Hutton (1883g: 477, 1884b: 182, 1884c: 201), Pilsbry (1892 [in 1892–1893]: 66), Hedley & Suter (1893: 638), and Suter (1894b: 251) recorded this species from Napier only. Suter (1913: 638) thought that “the locality Napier, as stated by Hutton, is wrong”, and that Hutton’s species was instead from the Three Kings Islands, and this reinterpretation has been followed by subsequent workers, including Powell (1935, 1948, 1951, 1979), Climo (1973), Spencer & Willan (1996: 40), Brook (1999 a, 2002) and Marshall & Barker (2008). Suter (1913: 637–638) gave a description of putative cassandra based on specimens collected by Thomas Cheeseman and Captain John Bollons on Great Island, Three Kings Islands, but an accompanying illustration ( Suter 1915: pl. 9, figs. 2, 2a, 2b) was of the type specimen previously illustrated by Pilsbry (1892 [in 1892–1893]: 66, pl. 22, figs. 37–39). Climo (1973: 568) suggested that the type material of cassandra had been collected on Three Kings Islands by Cheeseman, but this is incorrect because the latter’s first visit there, and indeed the first known visit to these islands by any naturalist, was in 1887 ( Cheeseman 1888, 1891), several years after the original description of this species.

Suter (1913) was undoubtedly correct in inferring that the record of Charopa cassandra Hutton, 1883 from Napier was erroneous. There are no extant or fossil land snail species known from Napier or elsewhere in the North Island that correspond to the descriptions and illustrations of this species, indicating that the type material was definitely mislocalised. However, although there are some similarities between Charopa cassandra as described by Hutton (1883g, 1884b) and illustrated by Pilsbry (1892 [in 1892–1893]) and Suter (1915), and the taxon from Three Kings Islands that was described by Suter (1913) and Marshall & Barker (2008), there are also some important morphological differences. These include the fact that the latter has a closed rather than a narrowly open umbilicus; it has weak, almost obsolete axial ribs on the teleoconch, rather than very fine ribbing; it has a less elevated spire; and it has a different colour pattern, with broad, radiating, reddish-brown streaks at the suture, that transform into more numerous, irregular, anastomosing, wavy or zigzag axial bands on the periphery and base. Re-examination of recently rediscovered type material of Charopa cassandra Hutton, 1883 indicates that it is in fact conspecific with, and a junior synonym of, Phacussa fulminata (Hutton, 1882) . The holotype of the latter species is a fresh, modern shell from Rakiura/Stewart Island (see entry for Zonites fulminata below), whereas the lectotype of Charopa cassandra Hutton, 1883 is a larger fossil shell that closely matches Phacussa fulminata from Holocene dune deposits on Native Island in Paterson Inlet, Rakiura. The species of Allodiscus from Three Kings Islands that was referred to as cassandra by Suter (1913) and subsequent authors is un-named and requires formal description.

Taxonomy. Treated here as a subjective junior synonym of Phacussa fulminata (Hutton, 1882) N. syn.