Antarctoscyphus admirabilis Pena Cantero, Svoboda & Vervoort 1999

Antarctoscyphus admirabilis Peña Cantero, Svoboda & Vervoort, 1999

(Fig. 12 A)

Antarctoscyphus admirabilis Peña Cantero et al., 1999: 1742 –1745, figs 1, 7A.

Material examined. Stn 17, stem fragment 65 mm long (MNCN 2.03/618); Stn 91, colony 180 mm high (NIWA 117546).

Measurements (in µm). Hydrotheca: length of abcauline wall 620, length of free part of adcauline wall 680, length of adnate part of adcauline wall 70, length of adcauline wall 750, diameter at aperture 230, maximum diameter 230. Cauline internodes: 1700 x 750.

Remarks. This uncommon species is easily distinguishable by its polysiphonic and branched stems, divided into short and thick internodes not arranged in zigzag, by its short, little branched, paired branches, with only a few hydrothecae and, sometimes, a few basal athecate internodes, and by the shape of the hydrotheca, cylindrical, but distinctly curved outwards, and with sharp cusps of similar development separated by deep embayments (Fig. 12 A).

Ecology and distribution. Shelf species, previously found only at 80 m depth (Peña Cantero et al. 1999); present material between 414 and 420 m, widely extending its lower bathymetric limit.

Hitherto only known from the eastern coast of the Weddell Sea (Peña Cantero et al. 1999), on the opposite side of the Antarctic continent. Present material, which constitutes the second record for the species, and the first one from the Ross Sea, comes from off Possession Islands and Cape Hallett, pointing to a circum-Antarctic distribution.