Staurotheca pachyclada ( Jäderholm, 1904 )

Peña Cantero, Álvaro L. & Marzal, Marina Fresneda, 2018, Benthic hydroids (Cnidaria: Hydrozoa) from off George V Coast (East Antarctica), Zootaxa 4441 (1), pp. 121-136 : 126-127

Staurotheca pachyclada ( Jäderholm, 1904)

( Fig. 3C )

Staurotheca pachyclada —Peña Cantero & Vervoort, 2003: 2698 –2702, figs 14–15 (synonymy).

Material examined. 29EV55, a stem 300 mm high (IK–2009–0370).

Description. Stem erect, polysiphonic, 300 mm high, with some perisarc constrictions. Branching only present in upper half of stem, alternate, almost in one plane. Branches up to third order present, narrowed basally. Hydrothecae present over entire colony, but only visible in monosiphonic parts. Hydrothecae arranged in verticils of three hydrothecae, forming siX longitudinal rows. Hydrotheca cylindrical ( Fig. 3C ), immersed into branch for two-thirds of its volume. Hydrothecal aperture circular, forming an acute angle with long aXis of stem.

Ecology and distribution. Our material was collected at depths between 471 and 499 m in George V Basin.

Circum-Antarctic distribution (Peña Cantero & Vervoort 2003).

Figures

FIGURE 3. Staurotheca antarctica Hartlaub, 1904: A, hydrothecae. Staurotheca nonscripta Peña Cantero, Svoboda & Vervoort, 1997: B, hydrotheca. Staurotheca pachyclada (Jäderholm, 1904): C, hydrotheca. Antarctoscyphus spiralis (Hickson & Gravely, 1907): D, internode with hydrotheca showing intrathecal cusps (arrow). Symplectoscyphus glacialis (Jäderholm, 1904): E, internode with hydrotheca. Halecium interpolatum Ritchie, 1907: F, incipient stem with distal hydrotheca (arrow pointing to characteristic long and straight basal part of internode). Abietinella operculata (Jäderholm, 1903): G, hydrotheca (arrow pointing to disc-shaped operculum) and nematotheca (arrow). Schizotricha nana Peña Cantero, Svoboda & Vervoort, 1996: H, unforked hydrocladial internodes showing hydrothecae and nematothecae. Oswaldella erratum Peña Cantero & Vervoort, 1997: I, hydrocladial internode showing hydrotheca and mesial inferior nematotheca (arrow). Scale bars: 200 µm.