Symplectoscyphus weddelli Peña Cantero, Svoboda & Vervoort, 2002

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 : 46

Symplectoscyphus weddelli Peña Cantero, Svoboda & Vervoort, 2002

( Figs 12 I, 13B)

Symplectoscyphus weddelli Peña Cantero et al. 2002: 1560 –1562, fig. 16; Peña Cantero, 2010a: 41 –42.

Material examined. Stn 53, fragment 10 mm long (MNCN 2.03/643); Stn 134, several incipient stems up to 13 mm high on tubes of benthic organism (NIWA 117588).

Description. Monosiphonic stems, up to 13 mm high. Typically unbranched (only three stems with primary branch). Stems divided into somewhat straight internodes. Hydrothecae alternately arranged in approximately one plane.

Hydrotheca ( Figs 12 I, 13B) roughly cylindrical, gradually curved abcaudally. Adcauline wall convex; without inflexion point where adcauline wall becomes free. Abcauline wall roughly straight basally and slightly concave at distal half. Cusp of hydrothecal aperture sharp and separated by deep embayments.

Measurements (in µm). Hydrothecae: length abcauline wall 350–400, length free part of adcauline wall 280–290, length adnate part of adcauline wall 280–350, length adcauline wall 560–570, diameter at aperture 160–180, maximum diameter 190, diameter at diaphragm 120. Cnidome: larger microbasic mastigophores, range 9.0–10.0 x 2.5–3.0, mean 9.5±0.4 x 2.7±0.2 (n=6); ratio, range 3.3–3.8, mean 3.6± 0.2 (n=6).

Remarks. Even when the infertile condition of the present material prevents a definitive identification, there are no significant differences with the original description of S. weddelli .

Ecology and distribution. Shelf species, collected at depths from 119 to 390 m ( Peña Cantero et al. 2002); present material between 60 and 197 m, epibiotic on tube of benthic organism.

Species reported only along the south and east coasts of the Weddell Sea ( Peña Cantero et al. 2002); studied material is the first record from the Ross Sea and East Antarctica , collected in Robertson Bay and off Cape Hallett, pointing to a circum-Antarctic distribution.

Figures

FIGURE 12. Antarctoscyphus admirabilis Peña Cantero, Svoboda & Vervoort, 1999: A, branch internode with hydrotheca. Symplectoscyphus aggregatus (Jäderholm, 1917): B, fragment of branch with hydrothecal arrangement and shape. Symplectoscyphus anae Peña Cantero, Svoboda & Vervoort, 2002: C, internode with hydrotheca. Symplectoscyphus densus sp. nov.: D – E, fragment of branch with hydrothecal arrangement and shape; Symplectoscyphus exochus Blanco, 1982: F, internode with hydrotheca. Symplectoscyphus liouvillei (Billard, 1914): G, internode with hydrotheca. Symplectoscyphus vanhoeffeni Totton, 1930: H, internode with hydrotheca. Symplectoscyphus weddelli Peña Cantero, Svoboda & Vervoort, 2002: I, internode with hydrotheca. Symplectoscyphus sp. 1: J, internode with hydrotheca. Symplectoscyphus sp. 2: K, internode with hydrotheca. (A from Stn 17; B from Stn 112; C from Stn 126; D from Stn 7 (holotype); E from Stn 97 (paratype); F from Stn 67; G from Stn 150; H from Stn 130; I, from Stn 53; J from Stn 7; K from Stn 25). Scale bar: 250 µm.