Oswaldella erratum Pena Cantero & Vervoort 1997

Oswaldella erratum Peña Cantero & Vervoort, 1997

(Figs 4, 16 D, 17D, 19D)

Material examined. German Antarctic Expedition ANT-XXI/2: Stn PS65 /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 24R, 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 95-24R).

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.