Hydrodendron arboreum ( Allman, 1888 )

ÁLVARO L. PEÑA CANTERO, 2017, Benthic hydroids (Cnidaria, Hydrozoa) from the Ross Sea (Antarctica) collected by the New Zealand Antarctic expedition BioRoss 2004 with RV Tangaroa, Zootaxa 4293 (1), pp. 1-65 : 53

Hydrodendron arboreum ( Allman, 1888)

Halecium arboreum — Hickson & Gravely, 1907: 27, pl. 4 figs 27–29; Dayton et al., 1970: 247, 254.

Ophiodes arboreus — Ritchie, 1913: 15, figs 2, 3.

Ophiodissa arborea — Totton, 1930: 142, fig. 2a.

Hydrodendron arboreum — Peña Cantero & Ramil, 2006: 952 –953, fig. 2C (synonymy); Peña Cantero & Gili, 2006: 766; Peña Cantero, 2008: 456; 2009: 1747; 2014a: 1720; Peña Cantero et al. 2013: 747, fig. 9a–c.

Material examined. Stn 21, three fragments up to 7 mm long (MNCN 2.03/655); Stn 112, a few stems and fragments, up to 45 mm long, some on pebbles, basibiont of Symplectoscyphus naumovi (NIWA 117603); Stn 134, at least one fragmented colony (largest fragment 230 mm long) (NIWA 117604); Stn 139, fragmented colony (largest fragment 70 mm long) (MNCN 2.03/656); Stn 140, several stem fragments up to 25 mm long, and complete stem 33 mm high, basibiont of Bimeria corynopsis (NIWA 117605); Stn 150, a few tiny stems, with just 2–3 polyps (NIWA 117606).

Ecology and distribution. Eurybathic species found at depths from 18 ( Hickson & Gravely 1907) to 1370 m ( Peña Cantero & Ramil 2006); present material between 60 and 480 m, epilithic on pebbles and basibiont for colonies of Bimeria corynopsis and Symplectoscyphus naumovi .

Pan-Antarctic distribution ( Peña Cantero & Ramil 2006). Recently reported from off Bouvet Island ( Peña Cantero & Gili 2006) and Livingston Island ( Peña Cantero 2008), in West Antarctica , and from the Balleny Islands (Peña Cantero 2009) and off Queen Mary Coast ( Peña Cantero 2014a), in East Antarctica . See Peña Cantero & Ramil (2006) for previous records. In the Ross Sea, already known from McMurdo ( Hickson & Gravely 1907; Ritchie 1913; Totton 1930; Dayton et al. 1970), Cape Royds ( Ritchie 1913) and Tethys Bay (Peña Cantero et al. 2013). Present material collected in Robertson Bay and off Cape Adare, Possession Islands and Moubray Bay .