(Fig. 15 F)
Halecium ovatum Totton, 1930: 143 –144, fig. 3; Peña Cantero et al., 2013: 745–747, fig. 6b. Halecium interpolatum — Peña Cantero, 2014b: 261 –263, figs 5G –J, 8A –B (synonymy).
Material examined. Stn 7, a few slightly polysiphonic stems up to 8 mm high on Antarctoscyphus grandis (NIWA 117594); Stn 67, two stems up to 3 mm high on Staurotheca nonscripta (MNCN 2.03/648); Stn 107, slightly polysiphonic stem ca. 19 mm high (NIWA 117595).
Measurements (in µm).Hydrothecae: diameter at aperture 150–245, diameter at diaphragm 100–145, height 45–65. Cnidome: microbasic euryteles (10.5–12.0 x 6.0–6.5) and microbasic mastigophores (6.5–7.0 x 2.0).
Remarks. Species easily identifiable by its typical scorpioid stems, with internodes arranged in zigzag and paired branches originating from hydrophore of primary hydrotheca, one on each side. Additionally, internodes characteristically have a long and straight basal part (Fig. 15 F). Hydrothecae are high, flared, with a strongly everted rim (Fig. 15 F).
Ecology and distribution. Recently reviewed by Peña Cantero (2014b). Shelf species collected at depths from three (Stepanjants 1979) to 471 m (Peña Cantero & García Carrascosa 1995); present material between 272 and 536 m, epibiotic on Antarctoscyphus grandis and Staurotheca nonscripta.
Circum-Antarctic distribution (Peña Cantero 2014b). In the Ross Sea, already known from off Cape Adare (Totton 1930) and Tethys Bay (Peña Cantero et al. 2013). Present material collected off Cape Adare, Possession Islands and Cape Hallet.