Antarctoscyphus admirabilis Peña Cantero, Svoboda & Vervoort, 1999

ÁLVARO L. PEÑA CANTERO, 2017, Benthic hydroids (Cnidaria, Hydrozoa) from the Ross Sea (Antarctica) collected by the New Zealand Antarctic expedition BioRoss 2004 with RV Tangaroa, Zootaxa 4293 (1), pp. 1-65 : 36

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.

Figures

FIGURE 12. Antarctoscyphus admirabilis Peña Cantero, Svoboda & Vervoort, 1999: A, branch internode with hydrotheca. Symplectoscyphus aggregatus (Jäderholm, 1917): B, fragment of branch with hydrothecal arrangement and shape. Symplectoscyphus anae Peña Cantero, Svoboda & Vervoort, 2002: C, internode with hydrotheca. Symplectoscyphus densus sp. nov.: D – E, fragment of branch with hydrothecal arrangement and shape; Symplectoscyphus exochus Blanco, 1982: F, internode with hydrotheca. Symplectoscyphus liouvillei (Billard, 1914): G, internode with hydrotheca. Symplectoscyphus vanhoeffeni Totton, 1930: H, internode with hydrotheca. Symplectoscyphus weddelli Peña Cantero, Svoboda & Vervoort, 2002: I, internode with hydrotheca. Symplectoscyphus sp. 1: J, internode with hydrotheca. Symplectoscyphus sp. 2: K, internode with hydrotheca. (A from Stn 17; B from Stn 112; C from Stn 126; D from Stn 7 (holotype); E from Stn 97 (paratype); F from Stn 67; G from Stn 150; H from Stn 130; I, from Stn 53; J from Stn 7; K from Stn 25). Scale bar: 250 µm.