Bougainvilliidae, Lutken, 1950

Soto, Joan J. & Peña, Álvaro L., 2019, Benthic hydroids (Cnidaria, Hydrozoa) from the Weddell Sea (Antarctica), Zootaxa 4570 (1), pp. 1-78 : 9-10

Bougainvilliidae undetermined

( Fig. 2 d–e)

Material examined. ANT XVII/3: 111-9, one stem, c. 5 mm high, with gonophores; 111-19, some stems, up to 8 mm high, on Schizotricha unifurcata Allman, 1883 and Symplectoscyphus weddelli Peña Cantero, Svoboda & Vervoort, 2002 , with gonophores; ANT XXI/2: PS65/39, some stems, up to 3 mm high, on Symplectoscyphus exochus Blanco, 1982 ; PS65/248, some stems, up to 10 mm high, on Halecium incertus Naumov & Stepanjants, 1962 , Stegella lobata ( Vanhöffen, 1910) and Symplectoscyphus curvatus ( Jäderholm, 1917) , with gonophores; PS65/280, few stems, up to 3 mm high; PS65/336, one stem, c. 3 mm high, on Symplectoscyphus glacialis ( Jäderholm, 1904) .

Remarks. Despite being abundant and fertile, the material examined does not agree with any of the bougainvillids reported from Antarctic waters. It has great resemblance with the syntypes of Bougainvillia macloviana Lesson, 1830 , re-described by Peña Cantero (2015), in colony and polyp shape, presence of pseudohydrotheca ( Fig. 2d ), and type and size of nematocysts (see below). However, the present material has clearly identifiable fixed sporosacs ( Fig. 2e ), with up to seven eggs, that arise from a large perisarc cup which rim is not well defined. In contrast, B. macloviana produces free medusae, and the gonophores originate from a welldefined, smaller, cup-shaped pedicel of perisarc ( Peña Cantero 2015, p. 373).

Cnidome composed by heteronemes [range 5.5–7.0 x 3.5–4.0 µm, mean 6.2±0.4 x 3.6±0.2 µm (n=29)] and desmonemes [range 3.0–3.5 x 2.0–2.5 µm, mean 3.3±0.3 x 2.3±0.3 µm (n=24)].

Ecology and distribution. Material examined collected at depths from 62 to 287 m off Cape Norvegia.

Figures

FIGURE 2. a–c Bimeria corynopsis: a stem showing branching; b stem showing annulation; c detail of polyp and slightly capitate tentacles. d–e Bougainvillidae undetermined: d polyp; e gonophore. f–i Rhizorhagium antarcticum: f colony shape; g extended (left) and contracted (right) polyps; h shape (left) and developing eggs (right) of female gonophores; i male gonophore. j?Sarsia sp.: polyp.