Rhytida patula Hutton, 1882

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 : 51-53

Rhytida patula Hutton, 1882

Pl. 6, figs. E, F

Hutton, 1882. The New Zealand Journal of Science, 1: 282.

Type material. Lectotype (designated by Powell 1946: 127), CMNZ M122 [ex ZS 823], and paralectotypes (5), CMNZ M121 (dry shells). The molluscan collection at CMNZ has a radula mounted on a glass slide with the label details ‘ Rhytida patula, Greymouth, XVI p. 167’, in Hutton’s handwriting (i.e., CMNZ 2017.17.59), which is probably primary type material (see radula descriptions by Hutton 1883d: 139, 1884b: 167).

Label details. CMNZ M121 —‘ Greymouth, Hutton coll.’, CMNZ M122 —‘ Greymouth, R. Helms coll.’, ‘ Lectotype sel. by A.W. B. Powell 1936 ’, and accompanying handwritten note ‘ Largest is holotype, agrees with Hutton’s dimensions. AWBP’.

CMNZ molluscan catalogue details. M121—‘ Rhytida patula Hutton, Greymouth , (old No., 121)’; M122— ‘ Rhytida patula Hutton, Greymouth , presumably Type, ( ZS 823)’.

Type locality. ‘Greymouth (R. Helms)’ ( Hutton 1882p: 282, 1883d: 139).

Previous illustrations of type material. Radula teeth illustrated by Hutton (1884b: pl. 10, fig. Q) probably from type material; Powell (1946: text figs. D4–6— lectotype).

Remarks. Hutton submitted a description of Rhytida patula to the Transactions and Proceedings of the New Zealand Institute issue for 1882, but publication was delayed until May 1883 ( Hutton 1883d: 139), and was preempted by a brief description in an account of a meeting of the Philosophical Institute of Canterbury ( Hutton 1882p: 282). A description by Hutton (1884b: 167, pl. 10, fig. Q) of a radula of patula was probably based on the putative type material in CMNZ 2017.17.59 mentioned above. As noted in the preceding species entry, Hutton (1883d: 139) differentiated R. patula from R. citrina , both described from material from Greymouth, on the basis of shell and animal coloration, and radula details. From the start there has been confusion over the identity and distribution of both species. Powell (1946: 127) noted that type material of R. patula at CMNZ comprised six ‘co-types’ and he selected the largest specimen, which most closely matched the shell dimensions given by Hutton (1883d: 138), as the lectotype, which is illustrated here in pl. 6, fig. F. Re-examination of this type series indicates that it is a mixed lot that contains two different species, a fact evidently not recognized by Hutton and other workers. One paralectotype (M121.5) is conspecific with the lectotype of R. patula , three match the neotype of R. citrina Hutton, 1882 and are interpreted here as that species (M121.1–M121.3), and one small juvenile shell was indeterminate (M121.4). One of the paralectotypes identified as R. citrina , M121.3, is illustrated here in pl. 6, fig. E. Records of R. patula from Balclutha by Hutton (1884b: 167, 1884c: 208), Hedley & Suter, (1893: 630) and Suter (1894b: 286, 1913: 777), based on CMNZ M1417, refer to a different species, Rhytida otagoensis Powell, 1930 . Powell (1946: 127, 1979: 345) recorded R. patula from several localities on the West Coast of the South Island between Whanganui Inlet and Lake Kaniere, and Parkinson (1979: 10) stated that this species was distributed over “most of the West Nelson block”. Efford (1998: 36, fig. 4J) mapped R. patula as having a wide distribution in the northwestern South Island, from Cape Farewell south to Shantytown (south of Greymouth) and Lewis Pass, albeit noting that this could be a complex of related species. Preliminary results of a phylogenetic study (M. Kennedy & T. King unpub. data) confirm this suspicion, and indicate that R. patula has a more restricted distribution than previously recognised (see below). Assigned to genus Rhytida Albers, 1860 by Hutton (1882) and subsequent authors, but this placement requires re-evaluation (M. Kennedy & T. King unpub. data).

Current taxonomy. Rhytida patula Hutton, 1882 — Hutton (1884b: 167, 1884c: 208), Hedley & Suter (1893: 630), Suter (1894b: 286, 1913: 776), Powell (1946: 127, 1979: 345), Parkinson (1979: 10), Efford (1998: 36), Spencer et al. (2009: 218).

Distribution. New Zealand; northern West Coast, coastal ranges between Charleston and Shantytown (AIM and NMNZ collection records).

Part 2: Land snail species introduced into New Zealand

Infraclass Pulmonata

Order Stylommatophora

Family AGRIOLIMACIDAE H. Wagner, 1935