Arion incommodus Hutton, 1879

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 : 54

Arion incommodus Hutton, 1879

Hutton, 1879. Transactions of the New Zealand Institute, 11 (1878): 331.

Type material. Syntypes (58), OMNZ IV5715 (in alcohol), and syntype (1), NHMUK 1886.11.18.25 (in alcohol). The molluscan collection at CMNZ has a radula and shell fragment mounted on glass slides with the label details ‘ Arion fuscus, Dunedin, XIV p. 154’, in Hutton’s handwriting (i.e., CMNZ 2017.17.50–2017.17.51), which are probably primary type material of Arion incommodus Hutton, 1879 (see radula description by Hutton 1882h: 154– 155).

Label details. OMNZ IV5715—‘ A. incommodus , = Arion subfusca Hutton, Dunedin (in Hutton’s handwriting)’.

NHMUK molluscan register details. 1886.11.18.25—‘ Arion incommodus Hutton, Dunedin, Purchased of the Commission for the New Zealand, Indian and Colonial Exhibition 1886’.

Type locality. ‘Dunedin, not uncommon in gardens etc.’ (Hutton 1879: 331).

Previous illustrations of type material. Hutton (1882h: pl. 3, figs. K, R—as Arion fuscus ; radula and jaw ‘from a Dunedin specimen’).

Remarks. The original label of the type material of Arion incommodus at OMNZ has been lost or destroyed, but transcribed details indicate that this material was collected and identified by Hutton himself. A specimen of A. incommodus that was mentioned by Cockerell (1891b: 221) as being “in the British Museum from Dunedin (Otago Univ. Mus.)” is possibly a syntype (NHMUK 1886.11.18.25). It was evidently sent to London as an exhibit in the Colonial and Indian Exhibition of 1886 and was subsequently purchased by the British Museum. Barker (1979: 418, 1999: 47) was apparently unaware of the type material of A. incommodus in OMNZ and referred to the NHMUK material as a “type specimen (?)”, and a “probable holotype ”, respectively. There has been confusion over the identity of Arion incommodus . Its distribution was initially listed as New Zealand only (Hutton 1879: 331, 1880: 26), but it was subsequently treated as a junior synonym of the European species Arion fuscus (Müller, 1774) (e.g., Hutton 1882h: 154, 1884c: 212; Simroth 1889: 65; Musson 1891: 890) and Arion subfuscus (Draparnaud, 1805) (e.g., Cockerell 1891b: 221; Suter 1892b: 280, 1913: 1072; Cockerell & Collinge 1893: 190, Hedley & Suter 1893: 665; Thomson 1922: 263). Barker (1979: 418, 1999: 45, 47) examined the specimen of A. incommodus at NHMUK and noted that it appeared to be a junior synonym of Arion hortensis Férussac, 1819 . Hutton’s (1879) description was the first record of this taxon from New Zealand. Barker (1982: 178, 1999: 46, 47, map 5) noted that A. hortensis was present in a wide range of modified habitats throughout the North and South islands but was less common in the southern South Island. Arion hortensis is native to northwestern Europe, and has been introduced to New Zealand, Australia, South Africa, North America, Madeira, St Helena and Sri Lanka ( Winter 1984: 9; Barker 1999:46; Herbert 2010; Welter-Schultes, 2012: 476).

Current taxonomy. A subjective junior synonym of Arion hortensis Férussac, 1819 — Barker (1982: 178, 1999: 98).

Family MILACIDAE Ellis, 1926