Helix chordata Pfeiffer, 1861

Brook, Fred J. & Ablett, Jonathan D., 2019, Type material of land snails (Mollusca: Gastropoda) described from New Zealand by taxonomists in Europe and North America between 1830 and 1934, and the history of research on the New Zealand land snail fauna from 1824 to 1917, Zootaxa 4697 (1), pp. 1-117 : 33-34

Helix chordata Pfeiffer, 1861

Pfeiffer, 1861: Malakozoologische Blätter, 8: 147.

Type material: According to Adolf Zilch, quoted by Cumber (1961: 179), “the type of P. chordata , originally held in the K. k. Hofmuseum [Vienna] but later removed to Stettin, was destroyed in World War II” .

Type locality: ’Neuseeland’ ( Pfeiffer 1861: 146).

Remarks: There are no published illustrations of type material of this species. The original description was based on one or more specimens obtained by Ferdinand von Hochstetter during his visit to New Zealand in 1858– 1859. Pfeiffer (1861: 147) listed the shell dimensions of Helix chordata as “Diam. maj. 3 ¾, min. 3 2 / 3, alt. fere 3 mill.”, and noted that this species “differs from the related H. iota Pfr. [= Helix pilula Reeve, 1852 ] in the topshaped [turbiniform] spire and the almost closed perforation”. The genus Phenacohelix Suter, 1892 was erected for H. pilula , H. chordata , and Helix granum Pfeiffer [ H. granum now in Granallodiscus —see entry for this species], with pilula nominated as the type species by subsequent designation of Pilsbry (1892a: 56) (see comments in entry for pilula below). Suter (1913b: 664) differentiated chordata from pilula primarily on the basis of umbilical width, without considering differences in spire elevation, and illustrated a relatively low-spired shell as putative chordata (i.e., Suter 1915: pl. 26, figs. 5, a, b). Cumber (1961) listed H. chordata as a junior synonym of H. pilula , noting that there was a large range of variation in riblet spacing, umbilical width, and shell height within and among populations, and that some populations contained a mix of perforate and imperforate shells. A later systematic review of the genus Phenacohelix by Goulstone (2001) erected two new species, P. aurea and P. mahlfeldae , for morphologically distinctive taxa that had previously been included in pilula . Both these species have a relatively high spire and narrow umbilicus, but it is unlikely that either is conspecific with H. chordata Pfeiffer. The shell of P. aurea differs from Pfeiffer’s description of chordata in being a uniform golden-brown colour, rather than ‘finely marbled in white and red’. Phenacohelix mahlfeldae is a close match to Pfeiffer’s description of chordata , albeit possibly with a more open umbilicus, but it has a distribution restricted to the southern South Island and Stewart Island, whereas Hochstetter’s specimen(s) of chordata were most likely collected in the North Island or northern South Island (see Introduction).

Current Taxonomy: Treated as a junior synonym of Helix pilula Reeve, 1852 [= H. iota Pfeiffer, 1853 ] by Cumber (1961: 177) and Powell (1979: 322), albeit without examination of type material.