Alexandrella schellenbergi

Alexandrella schellenbergi (Holman & Watling, 1983)

Bathypanoploea schellenbergi Holman & Watling, 1983: 47 (in part: holotype only) figs 11a–e only (not figs 9, 10, 11f–h: presumably A. pulchra and Alexandrella sp. 1).

Iphimediopsis australis – Schellenberg 1931: 127, pl. 1 fig. c.

Bathypanoploea australis – Schellenberg 1939: 137 (footnote, by implication).

non Acanthonotozoma australis Chilton, 1912: 205, pl. 2 fig. 19.

Sub-Antarctic Region: south of Argentine Basin: north east of Falkland Islands: 50°19ʹ S, 50°50ʹ W, 2675 m (Holman & Watling 1983).

It has been reported that Alexandrella schellenbergi has a very wide geographical and bathymetric distribution across the Southern Ocean (Holman & Watling 1983, Berge & Vader 2005b, 2005 c, De Broyer et al. 2007). This widespread distribution is questioned here. The holotype of A. schellenbergi was collected north of the Antarctic Polar Front and north of the line joining the Falkland Islands to South Georgia, at 2675 m. Its telson is more deeply cleft than in similar Alexandrella specimens from the continental shelf of the South Shetland Islands and the tip of the Antarctic Peninsula. This telson character state is consistent with the specimens illustrated in literature (Holman & Watling 1983, Ren & Huang 1991) and examined by us. On the poor quality photograph given by Schellenberg (1931), the posterior pereiopods also appear more slender than in the forms of the Antarctic continental shelf; however, this might be an illusion created by the possibly not flattened orientation of the legs on the picture. The telson difference, the geographical wide separation and the bathymetric differences suggest that two species are involved. The name Alexandrella pulchra Ren in Ren & Huang, 1991 is available for the form of the South Shetland Islands and the tip of the Antarctic Peninsula, and it is herein resurrected for them. All topotypical shelf specimens of Alexandrella pulchra examined by us were devoid of posterodorsal tooth on pereionite 6. However, specimens similar to A. schellenbergi with a tooth on pereionite 6 are present in the Ross Sea (Holman & Watling 1983: 49, fig. 10a), off Adélie Coast (present material) and in the Atlantic sector of the Southern Ocean (Rauschert & Arntz 2015). They are treated herein as a separate taxon: Alexandrella sp. 1.