Benthic hydroids (Cnidaria, Hydrozoa) from the Ross Sea (Antarctica) collected by the New Zealand Antarctic expedition BioRoss 2004 with RV Tangaroa Author ÁLVARO L. PEÑA CANTERO text Zootaxa 2017 2017-07-14 4293 1 1 65 journal article 32747 10.11646/zootaxa.4293.1.1 dc2674e2-e260-4b6e-ad3a-731d610bccc5 1175-5326 828475 6FF96B5C-1F80-47ED-9962-19603DCBF550 Halecium jaederholmi Vervoort, 1972 ( Fig. 15 G) Halecium jaederholmi — Peña Cantero, 2014b : 263 –266, fig. 9 (synonymy). Material examined. Stn 112, stem 90 mm high (NIWA 117596); Stn 170, two monosiphonic stems up to 15 mm high (MNCN 2.03/649). Measurements (in µm). Hydrothecae : diameter at aperture 180–245, diameter at diaphragm 170–240, height 25–30. Internodes : length 400–550, diameter at distal part 135–315. Hydrophore : length 70–150. Cnidome : microbasic euryteles? (13.0 x 6.0–7.0). Remarks. Branches originate from hydrophores and there are frequently short intermediate internodes at their base. Hydrothecae are alternately arranged in one or two planes, in this case forming an obtuse angle. The hydrotheca is at the end of an adnate hydrophore and its diameter hardly increases distally. The adcauline side of the hydrotheca, which is completely adnate to internode, is much developed, usually reaching the end of the internode ( Fig. 15 G). Ecology and distribution. Recently reviewed by Peña Cantero (2014b) . Shelf species found at depths between 24 ( Vervoort 1972a ) and 400 m ( Millard 1977 ); present material between 346 and 565 m . Probably Pan-Antarctic distribution (cf. Peña Cantero 2014b ). Present material is the first record from the Ross Sea, collected off Cape Adare and Adare Peninsula.