Antarctoscyphus grandis ( Blanco, 1977 )

Peña Cantero, Álvaro L., Roig Ferrer, Estela & Miranda, Thais P., 2017, Species of Antarctoscyphus Peña Cantero, García Carrascosa and Vervoort, 1997 (Cnidaria: Hydrozoa: Symplectoscyphidae) collected by US Antarctic expeditions: biogeographic implications, Journal of Natural History (J. Nat. Hist.) 51 (25 - 26), pp. 1437-1477 : 1460-1463

Antarctoscyphus grandis ( Blanco, 1977)

( Figure 10 )

Symplectoscyphus grandis Blanco, 1977, p. 6 , pl. 4, figs 14–16, pl. 5, figs 17–18.

Sertularella articulata – Vanhöffen, 1910, p. 328, fig. 42a–d.

Sertularella biformis – Totton, 1930, p. 199, fig. 45, pl. 2, fig. 8; Naumov and Stepanjants, 1972, p. 47, fig. 9; Stepanjants, 1979, p. 66, pl. 11, fig. 5.

? Symplectoscyphus mawsoni – Millard, 1977, p. 29, figs 8–9.

Antarctoscyphus grandis – Peña Cantero et al., 1997, p. 26; 1999, p. 1750–6, figs 4, 5, 7B–C; Peña Cantero, 2008, p. 458; 2010, p. 768; 2013, p. 130; Peña Cantero and Vervoort, 2009, p. 86–7.

Material examined

Eltanin: 6/436, five fragments, up to 25 mm long, with gonothecae; 12/1002, a few fragments, up to 25 mm long, with gonothecae; 27/1877, one stem fragment, c. 20 mm long; 32/2007, one branch fragment, c. 10 mm long; 32/2083, one hydrocladium in very bad condition; 32/2125, two fragmented stems, at least 160 mm high, with gonothecae. Hero : 691/032, one distal stem fragment, c. 75 mm long, with gonothecae; 721/730, one stem, c. 180 mm high; 731/1944, one stem, c. 25 mm high. Islas Orcadas: 575/040, one stem, c. 80 mm high; 575/061, one incipient stem, c. 28 mm high, and several fragments, up to 70 mm long, without hydrocladia; 575/069, one basally truncated stem, c. 140 mm high; 575/085, one basally truncated stem, c. 160 mm high, basibiont of Sertularella sp. ; 575/097, two fragments, c. 21 and 15 mm long.

Diagnosis

Stems basally polysiphonic, unbranched, up to 230 mm height, deprived of paired branches for most of their length. Cauline internodes straight or inconspicuously arranged in zigzag. Cauline apophyses alternately arranged in one plane; sometimes with a distinct spiral disposition. Paired branches strongly branched (up to sixth order). First second-order branch always originating from second internode of paired branch and always giving rise to a third-order branch at its third internode. Remaining branching irregular. Branch internodes size decreasing distally. Hydrothecae alternately arranged in two planes making an acute angle; strong tendency to unilateral disposition. Hydrothecae almost cylindrical, slightly curved outwards; adcauline hydrothecal wall free. Hydrothecal aperture cusps of similar development and separated by deep embayments. Gonothecae fusiform, with circular, distal aperture.

Ecology

Antarctoscyphus grandis has been collected on bottoms of pebbles ( Stepanjants 1979), bottoms with fragments of bryozoans and on muddy bottoms (Peña Cantero et al. 1999). Found epilithic on pebbles and gravel ( Peña Cantero 2008) and epibiotic on the hydroid Oswaldela antarctica ( Naumov and Stepanjants 1972) . Basibiont for colonies of the hydrozoans Filellum sp. (Peña Cantero et al. 1999; Peña Cantero 2013), Campanularia hicksoni ( Peña Cantero 2008) , Symplectoscyphus curvatus ( Peña Cantero 2008, 2013) and Sertularella sp. (present material). Gonothecae found in colonies collected in January ( Stepanjants 1979; Peña Cantero et al. 1999; Peña Cantero 2008) and February (Peña Cantero et al. 1999; Peña Cantero 2008, 2010, 2013; Peña Cantero and Vervoort 2009); we found gonothecae from January to March.

Bathymetric and geographic distribution

Eurybathic species, previously known from depths between 15 m ( Naumov and Stepanjants 1972) and 380 m (Peña Cantero et al. 1999); our material was collected

between 15 and 1042 m, considerably extending its bathymetric range to the upperslope.

Species with Circum-Antarctic distribution (Peña Cantero et al. 1997). In West Antarctica, reported off Low Island ( Blanco 1977; Peña Cantero 2013), Bransfield Strait ( Stepanjants 1979; Peña Cantero and Vervoort 2009), the south and east coasts of the Weddell Sea (Peña Cantero et al. 1999), off Deception and Livingston Islands, in the South Shetlands Islands area ( Peña Cantero 2008), off Elephant Island and off Bransfield Island, Antarctic Peninsula ( Peña Cantero and Vervoort 2009), and off Peter I Island ( Peña Cantero 2010). In East Antarctica, known off Cape Adare, the Ross Sea ( Totton 1930), off Adélie Coast ( Naumov and Stepanjants 1972) and from the Davis Sea ( Vanhöffen 1910). Our material was collected off South Georgia, Visokoi Island ( South Sandwich Islands), Elephant Island, King George Island (South Shetlands Islands), Deception Island and off Anvers Island, Palmer Archipelago (Antarctic Peninsula), in West Antarctica, and off Pennell Bank, Cape Hallett and Cape Adare (Victoria Land, Ross Sea), in East Antarctica.

Figures

Figure 10. Antarctoscyphus grandis (Blanco, 1977): (a) fragment of lateral branch showing branching and hydrothecal arrangement; (b) distal part of cauline internode showing axillary hydrotheca and basal part of paired branches; (c) hydrocladial branching; (d) hydrotheca; (e) fragment of branch showing hydrothecae and gonothecae; (f) detail of distal part of gonotheca. Scale bars: 1 mm (a, b), 500 µm (e), 250 µm (c), 200 µm (d), 50 µm (f).