Iophon flabellodigitatus var. gaussi Hentschel, 1914

(Fig. 7F)

Iophon flabello-digitatus var. gaussi Hentschel, 1914: 86, pl. VI fig.10.

Iophon flabellodigitatum var. gaussi; Goodwin et al. 2016: Table 2 (listed only).

The variety was described by Hentschel from Observatory Bay, Kerguelen, approximate coordinates 49.2°S 69.7°E, depth not given (syntype ZMB 4607, slide in BMNH 1929.1.22.20). Hentschel (1914) erected two varieties named gaussi in the genus Iophon Gray, 1867. Both are homonyms and usually (recommendation ICZN art. 24A) the one described first would be eligible to be the senior homonym bearing the name gaussi. However, Ríos (2006: 96) chose to elevate Iophon spatulatus var. gaussi, described on p. 87 to species level as Iophon gaussi (whereas I. flabellodigitatus var. gaussi was described on p. 86). The recommendation to indicate the name of the first described species as the senior homonym is not a strict rule, so Ríos’ choice made spatulatus var. gaussi the senior homonym. Iophon flabellodigitatus var. gaussi has differences with Kirkpatrick’s (1907: 277) typical variety (described from Winter Quarters, Ross Sea Antarctica, 65.1761°S 66.65417°W, depth 51–238 m, syntypes BMNH 1908.2.5.153– 155) in the shape (massively rounded in the present variety vs flabellate in the typical variety). Also, the length of the bipocillae may be different (15–16 µm vs 5.5–11µm respectively) and the shape and number of teeth appear subtly different.

Topsent (1917: 58) reported I. flabellodigitatum from Petermann Island, Antarctica. His specimens are encrusting the underside of boulders, but no skeletal details were described to support a possible identity as var. gaussi. Topsent did not mention Hentschel’s (1914) study when discussing I. flabellodigitatus, so, apparently, he was unaware of Hentschel’s varieties (although he did cite Hentschel’s paper in his list of references).

Brøndsted (1927a: 4) reported I. flabellodigitatum from Discovery Inlet, Antarctica, but gave no description other than that the “damaged and macerated” specimens agreed well with the type material.

Burton (1929: 442) synonymized all Antarctic Iophon species and varieties, including the present variety, to a single species I. radiatus Topsent, 1901. Burton did not discuss this decision in detail as he deemed the synonymy so obvious that he thought it “unnecessary to consider the subject in greater detail”. His conclusion was not followed by most later authors.

Koltun (1964: 56) assigned the present variety to the synonymy of I. spatulatum Kirkpatrick, 1907 without explanation.

Ríos et al. (2004: 101) reported I. flabellodigitatum from the South Shetland Islands with extensive description and illustrations. They did not mention Hentschel’s variety gaussi, but the habitus of their specimens is described as massive, not flabellate. Ríos (2006: 86) subsequently referred I. flabellodigitatum to the synonymy of I. unicorne Topsent, 1907, but failed again to mention the var. gaussi of that species.

Goodwin et al. (2016: table 2) list the variety without suggesting its status.

Since the present variety has some differences with the typical variety (even though this is now assumed to be a junior synonym of Iophon unicorne) and since junior homonyms must be replaced (ICZN art. 57.2) if they are considered to be a member of the same genus as the senior homonym (I. gaussi) then a replacement name is required for which I propose Iophon hentscheli nom.nov. It is likely that this is also a junior synonym of I. unicorne, but this has to be determined from comparative studies of the type material of both.