Bimeria corynopsis Vanhöffen, 1910

Peña Cantero, Álvaro L. & Marzal, Marina Fresneda, 2018, Benthic hydroids (Cnidaria: Hydrozoa) from off George V Coast (East Antarctica), Zootaxa 4441 (1), pp. 121-136 : 123-124

Bimeria corynopsis Vanhöffen, 1910

( Fig. 2 )

Bimeria corynopsis —Peña Cantero, 2015: 370–373, figs 1A, 2A–B, 3A–B (synonymy); 2017: 9, fig. 2A–B.

Material examined. 48EV194, colonies without polyps, with gonophores, on Staurotheca nonscripta Peña Cantero, Svoboda & Vervoort, 1997 and Symplectoscyphus glacialis ( Jäderholm, 1904) (IK–2012–10435), and on Staurotheca nonscripta (IK–2009–0300).

Description. Colonies with well-developed stems. Branching characteristic; branches roughly originating at right angle from stem and later curving upwards until becoming roughly parallel to stem. No polyps present. Gonophores at the end on annulated pedicels ( Fig. 2A–B ), globular, 230 µm high and 200 µm in maXimum diameter, covered by a thin layer of perisarc ( Fig. 2C–D ).

Cnidome (in µm): heteronemes (not seen discharged), range 7.0–9.4 X 3.0–5.7, mean 8.5±0.7 X 3.9±1.1 (n=11).

Remarks. The colonies have stems much more developed than previously reported, with up to 15 polyps. Even when the colonies are deprived of polyps, it is possible to recognize the species by the characteristic colony structure. The present material also agrees in the cnidome with previous findings. Peña Cantero (2014b) observed discharged nematocysts in material from the Davis Sea, confirming they are microbasic euryteles.

The gonosome of the species was previously unknown. The complete absence of polyps seems to indicate a complete investment in reproduction. The species has been reported a few times, always with many polyps, but without signs of reproductive structures.

Ecology and distribution. Present material collected at depths between 325 and 409 m, epibiotic on Staurotheca nonscripta and Symplectoscyphus glacialis . Gonophores present in December. Uncommon species endemic to East Antarctica ( Peña Cantero 2014b), so far only found three times, twice in the Davis Sea ( Vanhöffen 1910; Peña Cantero 2014b) and another in the Ross Sea (Peña Cantero 2017).

Figures

FIGURE 2. Bimeria corynopsis Vanhöffen, 1910: A–B, fragments of stems with gonophores; C–D, detail of gonophores. Scale bars: 200 µm (A–B), 100 µm (C–D).