(Figs 4, 16 D, 17 D, 19 D)
Material examined. German Antarctic Expedition ANT-XXI/ 2: Stn PS 65 / 166 - 1, Polarstern, 15 December 2003, 70°56.83’– 70 °56.00’, 10 °32.61’– 10 °30.53’W (off Cape Norvegia, Weddell Sea), 338 – 253 m. Spanish Antarctic Expedition Bentart 95: Stn 24 R, Hespérides, 30 January 1995, 63°58.4715’S, 60 °51.9882’W (off Trinity Island, Graham Land), 214 m (Department of Zoology, University of Valencia, BENTART 95 - 24 R).
Description. Monosiphonic (occasionally polysiphonic), unbranched stems, up to 130 mm high, usually not divided into internodes. Typically, perisarc strongly developed. Angle between cauline apophyses and stem ca. 70 °. Cauline apophyses with two axillary nematophores, each provided with a much-reduced nematotheca (Fig. 4 B).
Hydrocladia branched, up to third-order hydrocladia reported. First hydrocladial internode bifurcated, with two similar prongs (Fig. 4 A). Mesial-inferior nematophore on a strongly marked swelling at proximal third of internode (Fig. 4 D–E); with scale-shaped nematotheca (Fig. 4 D–F). Hydrotheca elongate, placed on middle of internode (Fig. 4 A, D–E). Abcauline wall of hydrotheca basally straight, but strongly curving adcaudally at distal part (Fig. 4 E). Hydrothecal aperture kidney-shaped (Fig. 4 C), adcaudally directed (Fig. 4 E).
Gonothecae fusiform. Female gonotheca larger than male one, with subterminal, circular aperture. Male gonotheca with distal, circular aperture (Fig. 4 G).
Remarks. The most remarkable finding in relation to this species is the presence of much-reduced nematothecae in the axillary nematophores, never described before.