Patula bianca Hutton 1883

Patula bianca Hutton, 1883

Pl. 2, fig. B

Hutton, 1883. New Zealand Journal of Science, 1: 475.

Type material. Formerly in Canterbury Museum, Christchurch (Hutton 1898 – 1900: 9, Suter 1913: 704), but not listed in the M catalogue. It was reported as missing by Freeman et al. (1997: 36), was not found during a search of the molluscan collection in 2017, and has apparently been lost.

Type locality. ‘Greymouth (R. Helms)’ (Hutton 1883g: 475, 1884b: 175).

Remarks. 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: 175), and was preempted by a brief description in an account of a meeting of the Philosophical Institute of Canterbury (Hutton 1883g: 475). Hutton (1883g, 1884b) recorded P. bianca from Greymouth only, and Hutton (1884c: 192) listed additional records from ‘Auckland’ and ‘Horokiwi, Wellington’ in North Island, and ‘Bealey’ in South Island. There are no published illustrations of the type material of Patula bianca Hutton, 1883 and, as already noted, the type specimen(s) appears to have been lost. Nevertheless, Hutton’s (1884b: 175) description is accordant with one particular species living in the vicinity of Greymouth. Examination of the literature and museum collections indicates that this taxon was identified as bianca by Henry Suter, who undoubtedly would have examined the type material that was formerly present in Canterbury Museum, Christchurch, when he was working there (see Hyde 2017). New Zealand malacologists following on from Suter have also consistently used this name for the same taxon. One other species living in the vicinity of Greymouth, Paracharopa rimu Climo, 1985, has very similar shell morphology to, and is locally syntopic with bianca, but differs from Hutton’s (1884b: 175) description of the latter species in lacking a radial colour pattern. The fact that there does not appear to have been confusion over the identity of P. bianca means that designation of a neotype is not warranted. Suter (1892e: 293, pl. 21, figs. 21, 22), described and illustrated the jaw and radula of a specimen(s) from ‘Forty-mile Bush, North Island’. The first illustrations of a shell of P. bianca were by Pilsbry (1892 [in 1892–1893]: 97, pl. 37, figs. 41, 42), probably based on material that had been sent to him by Suter (i.e., ANSP 63792, 63793). Descriptions of the shell, radula and reproductive anatomy of bianca were given by Suter (1913: 703, 1915: pl. 27, fig. 18, a) and Climo (1970: 290, table 2, text figs. 8F, 13F, 20C, 22I, pl. 1, fig. D). A topotype of Patula bianca Hutton, 1883 from near Point Elizabeth, on the northern outskirts of Greymouth, is illustrated here in pl. 2, fig. B (NMNZ M.329345). Hedley & Suter (1893: 655), Suter (1893: 147, 152) and most subsequent authors have assigned this species to Charopa Albers, 1860 at genus or subgenus level. However, preliminary results of a phylogenetic study indicate that it belongs instead in Paracharopa Climo, 1983 (M. Kennedy unpub. data), as has been suggested previously by Mayhill (1994: 31, 32, 37, 38) and Worthy & Holdaway (1994: 391). This species has a very wide distribution in the New Zealand region (below).

Taxonomy: Treated here as Paracharopa bianca (Hutton, 1883) —after Mayhill (1994), Worthy & Holdaway (1994).

Distribution. New Zealand; North Island (sparse north of Auckland), Aotea/Great Barrier Island, Mercury Islands, Kapiti Island, islands in Marlborough Sounds, South Island, islands in Fiordland, Rakiura/Stewart Island and nearshore islands, Whenua Hou/Codfish Island, Chatham Islands and Antipodes Islands (Hutton 1884c: 192; Suter 1913: 704; Powell 1955: 125; Climo 1970: 291, fig. 2A; AIM and NMNZ collection records). Records of Charopa bianca (Hutton) from Auckland Islands by Powell (1979: 303), Spencer & Willan (1996: 39) and Pugh & Scott (2002: 933) appear to be in error.