(Fig. 19 A)
Oswaldella rigida — González Molinero & Peña Cantero, 2015: 416 –419, 437–438, figs 11, 16K, 18C, 20C (synonymy).
Material examined. Stn 88, stem 68 mm high (NIWA 117342).
Remarks. The material studied agrees with this species. The stem is unbranched and undivided. There is no node between cauline apophyses and hydrocladia. These are perpendicular to the stem and bifurcated. Finally, there are two axillary nematophores on cauline apophyses. The length of the hydrothecal abcauline wall is 260–320 µm. See González Molinero & Peña Cantero (2015) for a SEM study on this material.
Ecology and distribution. Recently revised by González Molinero & Peña Cantero (2015). Shelf and slope species (González Molinero & Peña Cantero 2015), found at depths between 80 (Peña Cantero et al. 1997b) and 1157 m (Peña Cantero 2014a); present material at 515 m.
Circum-Antarctic distribution (Peña Cantero et al. 1997b). Present material is the first record from the Ross Sea, collected off Cape Hallet.