Oswaldella occulta Cantero & Molinero 2018, sp. nov.

• Main Authors: Cantero, A. L. Peña, Molinero, A. González
• Format: Other/Unknown Material
• Language: unknown
• Published: 2018
• Subjects: Biodiversity; Taxonomy; Animalia; Cnidaria; Hydrozoa; Leptothecata; Kirchenpaueriidae; Oswaldella; Oswaldella occulta; Antarctic; Ross Sea; New Zealand; Adare; Cape Adare; Molinero; Antarc*
• Online Access: https://zenodo.org/record/5960858; https://doi.org/10.5281/zenodo.5960858

Oswaldella occulta sp. nov. (Figs 7–8) Oswaldella sp. GOnzález MOlinerO & Peña CanTerO, 2015: 422, figs 15, 16P, 18H, 20H; Peña CanTerO, 2017: 60, fig. 19C. Material examined. From the type series of Oswaldella terranovae: British Antarctic Terra Nova Expedition 1910–1913, Stn 220, 3 January 1912, off Cape Adare, Ross Sea, 82 – 92 m, several stems up to 120 mm high (NHM 1929.10.28.171), one slide with hydrocladia (1929.10.28.171, labelled n° 4), and four stems up to 130 mm high (NHM 1929.10.28.172). A 57-mm-long, basally broken stem from the material with the collection number NHM 1929.10.28.172 is designated as holotype (all the remaining material is paratype). Other material examined: New Zealand Antarctic Expedition TAN0402, Stn 178, Tangaroa, 27 February 2004, 71°31’89’’–71°32’16’’S, 171°18’31’’–171°18’70’’E (Cape Adare, Ross Sea), 343–348 m (identified as Oswaldella sp. by González Molinero & Peña Cantero 2015). Description. Stems at least 130 mm high, unbranched and slightly polysiphonic basally. Stem thin, yellowbrown, divided into internodes separated by strongly marked nodes. From one to three apophyses per internode. Angle between cauline apophyses and stem c. 45°. Cauline apophyses with two axillary nematophores, each emerging through a simple hole in perisarc (Fig. 7B); no ‘mamelons’ present. Apophyses short, distinctly separated from hydrocladia. Hydrocladia much branched (Fig. 7A), with up to six third-order hydrocladia, three on each secondary hydrocladium (in one case with four tertiary hydrocladia on a secondary hydrocladium); occasionally, a short fourth-order hydrocladium was present. Tertiary hydrocladia placed lower than secondary ones. Hydrocladia divided into internodes, barely decreasing distally in size; e.g. 1000–930 µm in length and 280–270 µm in diameter under hydrotheca, in 1 st and 8th unforked internodes of secondary hydrocladium, respectively. First hydrocladial internode bifurcated (Fig. 7A), with two similar prongs, distinctly separated from first internode of secondary ...