Halecium jaederholmi Vervoort, 1972

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 : 50-51

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.

Figures

FIGURE 15. Halecium banzare Watson, 2008: A, internodes with primary and second-order hydrothecae; B, gonotheca. Halecium exaggeratum Peña Cantero, Boero & Piraino, 2013: C, internode with primary and secondary hydrotheca as well as lower-order branch; D, internodes with primary hydrothecae; E, gonotheca. Halecium interpolatum Ritchie, 1907: F, internode with primary hydrotheca and internode structure. Halecium jaederholmi Vervoort, 1972: G, internodes with primary hydrothecae. Halecium secundum Jäderholm, 1904: H, internode with primary hydrotheca. (A from Stn 53; B from Stn 139; C – E, H from Stn 67; F from Stn 107; G from Stn 112). Scale bar: 250 µm.