Antarctoscyphus admirabilis Peña Cantero, Svoboda and Vervoort, 1999

Peña Cantero, Álvaro L., Roig Ferrer, Estela & Miranda, Thais P., 2017, Species of Antarctoscyphus Peña Cantero, García Carrascosa and Vervoort, 1997 (Cnidaria: Hydrozoa: Symplectoscyphidae) collected by US Antarctic expeditions: biogeographic implications, Journal of Natural History (J. Nat. Hist.) 51 (25 - 26), pp. 1437-1477 : 1444-1446

Antarctoscyphus admirabilis Peña Cantero, Svoboda and Vervoort, 1999

( Figure 2 )

Antarctoscyphus admirabilis Peña Cantero et al., 1999, p. 1742 –5, figs 1, 7A.

Material examined

New Zealand Antarctic Expedition BioRoss 2004, RV Tangaroa: Stn 91, 14–02–2004, 72°16.61 ʹ – 72°16.74’ S, 171°26.94 ʹ – 171°25.97 ʹ E (off Cape Hallett, Victoria Land, Ross Sea), 409–414 m, one colony, c . 180 mm high.

Diagnosis

Colonies up to 210 mm high, consisting of erect, branched stems (up to fourth order). Largest stems basally polysiphonic. Stem internodes short and thick, limited by strong perisarc constrictions, and not arranged in a zigzag pattern. Cauline apophyses strongly directed upwards, alternately arranged, but with inconspicuous spiral variation. Paired branches divided into short and wide hydrothecate internodes; sometimes with one to three basal athecate internodes. Paired branches of similar length, short, with only a few hydrothecae and slightly branched. Each paired branch branching at second and fifth internodes, giving rise to secondary branches; first second-order branch usually branching at third internode, forming one tertiary branch that, occasionally, gives rise to one fourth-order branch. Hydrothecae alternately arranged in two planes forming an acute angle. Hydrotheca cylindrical, but distinctly curved outwards. Adcauline wall completely free. Cusps of hydrothecal aperture of similar development, sharp and separated by deep embayments. Gonothecae unknown.

Bathymetric and geographic distribution

Species previously known only off Atka Iceport, on the eastern coast of the Weddell Sea, where it was found at a depth of 80 m (Peña Cantero et al. 1999). Peña Cantero (unpublished) has also found the species off Possession Islands and Cape Hallett, in the Ross Sea region, pointing to a Circum-Antarctic distribution.

Figures

Figure 2. Antarctoscyphus admirabilis Peña Cantero, Svoboda and Vervoort, 1999: (a) two paired branches, showing branch ramification and hydrothecal arrangement; (b) cauline apophysis with axillary hydrotheca and basal part of two paired branches; (c, d) hydrothecae; (e) detail of hydrothecal distal part, showing cusps and opercular flaps. Scale bars: 500 µm (a), 250 µm (b, c), 150 µm (d), 50 µm (e).