Filellum antarcticum ( Hartlaub, 1904 )

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 : 23

Filellum antarcticum ( Hartlaub, 1904)

Reticularia antarctica — Totton, 1930: 160 –161, fig. 17.

Filellum antarcticum— Peña Cantero et al., 2004: 2283–2287 figs 2C–F, 3, 4 (synonymy); Peña Cantero, 2008: 453; 2010b: 764–765, fig. 3a–c; 2012: 856–557; 2013: 127–128; 2014a: 1717.

Material examined. Stn 130, numerous hydrothecae on Billardia subrufa ( Jäderholm, 1904) , with coppiniae (NIWA 117487); Stn 132, several hydrothecae on Billardia subrufa , with coppiniae (MNCN 2.03/533).

Measurements (in µm). Hydrotheca: diameter at aperture 100–150. Cnidome: larger size group (12.0–15.0 x 4.0–5.0); smaller size group (6.0 x 3.0).

Remarks. As typical for this species, the defensive tubes of the coppinia surround the gonothecae and create a breeding chamber; the defensive tubes are provided with a distal aperture. Also characteristically, gonothecae are deprived of distal neck. Hydrotheca with striae on the upper side of adnate part.

Ecology and distribution. Shelf species (Peña Cantero et al. 1998), found at depths between 14 ( Millard 1964, 1975) and 540 m ( Peña Cantero 2012); present material from 120 to 172 m, epibiotic on Billardia subrufa and with coppiniae in February.

Mainly distributed in Antarctic waters, but also known off South Africa (cf. Peña Cantero et al. 2004). Recently reported off Livingston Island ( Peña Cantero 2008), Peter I Island ( Peña Cantero 2010b), the Bellingshausen Sea ( Peña Cantero 2012), and off Low Island (Peña Cantero 2013), in West Antarctica , and off Queen Mary Coast ( Peña Cantero 2014a), in East Antarctica . See Peña Cantero et al. (2004) for previous records. In the Ross Sea, already known from McMurdo Sound and off Cape Adare ( Totton 1930). Present material collected in Robertson Bay and off Cape Adare.