Alexandrella pulchra Ren in Ren & Huang 1991

Alexandrella pulchra Ren in Ren & Huang, 1991

Fig. 337

Bathypanoploea schellenbergi Holman & Watling, 1983: 47, in part, figs 9a, 9c-f, 11g–h only (not the holotype).

Alexandrella pulchra Ren in Ren & Huang, 1991: 291–292, 321–323, fig. 64.

Bathypanoploea schellenbergi – Coleman 1990b: 197, figs 1–3. — Coleman 1992: 140, fig. 3–4. — Nyssen 2005: 130, unnumbered fig. — Berge & Vader 2005b: 83 (in part). — Berge & Vader 2005b: 83 (in part). — Berge & Vader 2005c: 4 (in part), fig. 5.

Alexandrella sp. –? Rauschert & Arntz 2015: 79, pl. 72 [Bentart 94, Livingston Island].

Material examined

RV Polarstern cruises:

SOUTHERN OCEAN: 1 spec., orange form, cruise PS69, ANT-XXIII/8, stn 654-6, Elephant Island, 61°22.80ʹ S, 56°03.84ʹ W to 61°23.35ʹ S, 56°04.89ʹ W, 341–342 m, Agassiz trawl, 29 Dec. 2006, coll. C. d’Udekem d’Acoz and H. Robert (RBINS, INV. 122440); 1 spec., orange form, cruise PS69, ANT- XXIII/8, stn 662-1, between Elephant Island and King George Island, 61°35.91ʹ S, 57°17.04ʹ W to 61°35.41ʹ S, 57°20.60ʹ W, 425–432 m, bottom trawl, 30 Dec. 2006, coll. C. d’Udekem d’Acoz and H. Robert (RBINS, INV. 122304); 1 spec., colour unrecorded, cruise PS71, ANT-XXIV/2, ANDEEP- SYSTCO, stn 48-1, east of Weddell Sea, 70°23.94ʹ S, 8°19.14ʹ W to 70°23.89ʹ S, 8°18.67ʹ W, 595–602 m, bryozoan bottom (exceptional bryozoan diversity), Rauschert dredge, 12 Jan. 2008, coll. H. Robert (RBINS, INV. 132623) [extraction EAS of 10 Feb. 2012; Genbank nr, 28S: KT808699, 18S: KT808768]; 1 spec., orange and white form, cruise PS81, ANT-XXIX/3, stn 217-6, Bransfield Strait, 62°53.45ʹ S, 58°13.06ʹ W to 62°53.42ʹ S, 58°13.41ʹ W, 421-483 m, rich sponge bottom, Agassiz trawl, 2 Mar. 2013, coll. C. d’Udekem d’Acoz and M. Verheye (RBINS, INV. 122865); 1 spec., orange and white form, cruise PS81, ANT-XXIX/3, stn 227-2, Bransfield Strait, 62°55.83ʹ S, 58°41.09ʹ W to 62°55.76ʹ S, 58°41.46ʹ W, 562–564 m, muddy bottom, Agassiz Trawl, 5 Mar. 2013, coll. C. d’Udekem d’Acoz and M. Verheye (RBINS, INV. 122864).

Colour pattern and eyes description

Head whitish; eyes very large, non-ommatidian and white, forming a large V pointing forwards; body entirely orange (orange form) or orange except for mid-dorsal crests of pleon, which are largely white

(orange and white form); pereiopods and antennae orange (orange form) or largely white (orange and white form). The eyes disappear in alcohol.

Distribution

Reliable records are from the South Shetland Islands, Bransfield Strait and the eastern shelf of the Weddell Sea, 341– 602 m.

Biology

The analyses of gut contents by Coleman (1990b) revealed the occurrence of ossicles of holothurians in the digestive tract of Alexandrella pulchra (as Bathypanoploea schellenbergi). Gut content analyses of the latter species by Dauby et al. (2001a) revealed gorgonian remains (cnidocysts and ossicles), plankton and hard remains of crustaceans, bryozoans and holothurioids.

Remarks

The reasons for re-establishing Alexandrella pulchra as a distinct species are given in the remarks section on A. schellenbergi. In A. pulchra, some specimens have orange pereiopods and antennae and others nearly entirely white appendages. Two explanations are possible: Either the specimens exhibit individual colour variation or two very similar species are involved. The identity of the Alexandrella sp. of Rauschert & Arntz (2015) is not clear but it might be A. pulchra. The shape of the eye and the number of body segments with a tooth match with A. pulchra but coxa 4 seems to be apically rounded instead of subacute.