Halecium banzare Watson, 2008

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 : 48

Halecium banzare Watson, 2008

( Fig. 15 A–B)

Halecium banzare — Peña Cantero, 2014b: 249 –251, fig. 3A–D (synonymy).

Material examined. Stn 8, stem 60 mm high (MNCN 2.03/646); Stn 53, strongly polysiphonic stem 90 mm high (NIWA 117591); Stn 139, two colonies 60 and 70 mm high, with male gonothecae, on pebbles and calcareous bryozoans (NIWA 117592); Stn 171, distal stem fragment 12 mm long (MNCN 2.03/647).

Description. Stem robust, strongly polysiphonic, up to 90 mm high. Branching regular, with alternate, paired branches every third hydrotheca. Stem and branches divided into internodes by alternately arranged oblique nodes. Hydrophore long, free, with distal hydrotheca ( Fig. 15 A) (ratio adcauline length of hydrophore:diameter at diaphragm 1.4–1.5), bent adcaudally, resting close to internode, forming basal convexity at abcauline side. Hydrothecae widely surpassing distal node of internode. Cauline hydrothecae with pseudodiaphragm. Hydrothecal diameter distinctly increasing from diaphragm upwards, with asymmetrical pattern ( Fig. 15 A): abcauline wall straight or slightly directed outwards, adcauline wall distinctly curved adcaudally. Height of hydrotheca asymmetrical, deeper at abcauline side. Single secondary hydrotheca usually at end of short pedicel ( Fig. 15 A).

Gonotheca flattened, triangular, narrowing towards base ( Fig. 15 B).

Measurements (in µm). Hydrotheca: diameter at aperture 150–180, diameter at diaphragm 130–150, height 40–70. Hydrophore: adcauline length 180–220. Gonotheca: height ca. 825, maximum diameter ca. 500. Cnidome: microbasic mastigophores (6.5– 7 x 1.5–2) and microbasic euryteles (7– 8 x 3–4).

Remarks. In the material from Stn 53, apart from the regular microbasic euryteles, there are scarce larger microbasic euryteles (9.0–10.0 x 5.0–6.0 µm). I cannot discard the possibility that they are aloctonous.

Ecology and distribution. Recently reviewed by Peña Cantero (2014b). Shelf species collected at depths from 200 ( Broch 1948) to 603 m ( Watson 2008); present material between 197 and 564 m, epilithic on pebbles and epibiotic on calcareous bryozoan, and with gonothecae in February.

Circum-Antarctic distribution ( Peña Cantero 2014b). Present material is the first record from the Ross Sea, collected off Adare Peninsula, Possession Islands, Moubray Bay and Cape Hallet.

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.