Staurotheca densa Peña Cantero & Vervoort, 2003

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, Magnolia Press : 29-31

Staurotheca densa Peña Cantero & Vervoort, 2003

( Fig. 10 B)

Staurotheca densa Peña Cantero & Vervoort, 2003: 2678 –2680, fig. 6 (synonymy); Peña Cantero, 2008: 459; 2009: 1749.

Material examined. Stn 24, fragment 7 mm long, in bad condition (NIWA 117520); Stn 25, four colonies up to 40 mm in diameter, with female gonothecae, basibiont of Rhizorhagium antarcticum (MNCN 2.03/552); Stn 48, two fragments, 20 and 14 mm long (NIWA 117521); Stn 52, fragment 20 mm long (NIWA 117522); Stn 53, one stem 55 mm high basibiont of Rhizorhagium antarcticum , and one fragment 18 mm long basibiont of Hebella plana (MNCN 2.03/553); Stn 63, mass of branches, ca. 60 mm long, with female gonothecae (NIWA 117523); Stn 67, three palmate colonies up to 160 mm high, mass of stems ca. 30 mm in diameter, and four fragments up to 42 mm long (MNCN 2.03/554); Stn 96, colony 85 mm long (NIWA 117524); Stn 123, colony fragment 70 mm long (MNCN 2.03/555); Stn 125, several fragments up to 28 mm long (NIWA 117525); Stn 126, six colonies up to 200 mm high and 130 mm wide, with male and female gonothecae, basibiont of Hebella plana , Lafoea dumosa , Symplectoscyphus anae Peña Cantero, Svoboda & Vervoort, 2002 , and Symplectoscyphus sp. (NIWA 117526); Stn 129, one fragment 6 mm long (NIWA 117527); Stn 130, 16 colonies up to 200 mm high and 120 mm wide, with male and female gonothecae, basibiont of Abietinella operculata , Antarctoscyphus spiralis , Billardia subrufa , Campanularia hicksoni , Halecium tangaroa sp. nov., Lafoea dumosa , Symplectoscyphus sp., and Rhizorhagium antarcticum (NIWA 117528); Stn 132, at least two colonies up to 190 mm high, with male and female gonothecae, basibiont of Halecium sp. and Sympletoscyphus sp. (MNCN 2.03/556); Stn 197, mass of stems ca. 70 mm in diameter, with female gonothecae (MNCN 2.03/557); Stn 198, two fragments up to 20 mm long (NIWA 117529).

Measurements (in µm). Hydrotheca: abcauline wall 680–730, free part of adcauline wall 260–360, adnate part of adcauline wall 500–590, adcauline wall 850–880, diameter at aperture 260–280. Larger nematocysts: 20–21.5 x 5.

Remarks. The colonies may be polysiphonic basally. Although this species typically has three to four hydrothecae per verticil, decussate pairs are occasionally found. This species is also characterized by having a slight, but distinct abcauline projection at the hydrothecal aperture ( Fig. 10 B).

Ecology and distribution. Reviewed by Peña Cantero & Vervoort (2003). Shelf species found at depths between 73 and 570 m ( Peña Cantero & Vervoort 2003); present material from 110 to 736 m, increasing its lower bathymetric limit, basibiont for colonies of Abietinella operculata , Antarctoscyphus spiralis , Billardia subrufa , Campanularia hicksoni , Halecium tangaroa sp. nov., Halecium sp., Hebella plana , Lafoea dumosa , Rhizorhagium antarcticum , Symplectoscyphus anae , and Symplectoscyphus sp., and with gonothecae in February.

Circum-Antarctic species ( Peña Cantero & Vervoort 2003), recently recorded from off Trinity Island ( Peña Cantero 2008) and from the Balleny Islands (Peña Cantero 2009). See Peña Cantero & Vervoort (2003) for previous records. In the Ross Sea, already known off Cape Hallett and Pennell Bank ( Peña Cantero & Vervoort 2003). Present material from Robertson Bay and off Cape Adare, Adare Peninsula, Possession Islands and Cape Hallett.

Figures

FIGURE 10. Staurotheca compressa Briggs, 1938: A, hydrotheca. Staurotheca densa Peña Cantero & Vervoort, 2003: B, hydrotheca. Staurotheca dichotoma Allman, 1888: C, hydrotheca. Staurotheca gracilis sp. nov.: D, basal part of a branch with hydrothecal arrangement; E – G, hydrothecae. Staurotheca nonscripta Peña Cantero, Svoboda & Vervoort, 1997: I, hydrotheca. (A, from Stn 178; B from Stn 67; C, from Stn 140; D – E, G – H from the holotype; F from the paratype; I from Stn 148). Scale bar: 250 µm (A – C, E – H), 500 µm (D).