Opercularella

Galea, Horia R. & Schories, Dirk, 2012, Some hydrozoans (Cnidaria) from King George Island, Antarctica, Zootaxa 3321, pp. 1-21 : 7

Opercularella sp.

( Fig. 2 D)

Material examined. Stn. RAS — 19.ii.2010, Ant.04/2010 (43 m): sterile colonies epizoic on Antarctoscyphus spiralis (MHNG-INVE-79793); Ant.14/2010 (43 m): sterile colony on plumose bryozoan (MHNG-INVE-79789).

Description. Hydrorhiza reptant, giving off pedicellate hydrothecae at irregular intervals. Pedicels slender (50–70 µm wide) and of varied length (155–730 µm), either unbranched or sparingly and irregularly branched once or twice; perisarc spirally grooved, slightly widening distally and merging smoothly into hydrotheca; pedicel and hydrotheca delimited by delicate "diaphragm". Hydrothecae 360–560 µm long, lateral walls slightly divergent, widest (110–160 µm) at opercular base; operculum membranous, conical, pleated, not delimited basally by crease line. Gonothecae absent.

Remarks. The sterile condition of the present material prevent us from providing a reliable identification for this species. It may belong to Opercularella belgicae ( Hartlaub, 1904) , but hydrothecal pedicels of this species appear to be smooth, except for the presence of 2–3 basal, spiral annulations (see Galea 2007).

Figures

FIGURE 2. A – C: Hydractinia angusta Hartlaub, 1904 — fragment of colony showing gastro-, gonozooid, and spine (A); gonozooid (B); cnidome (C). D: Opercularella sp. — hydrothecate pedicel. E, H: Halecium antarcticum Vanhöffen, 1910 — stem internode (E); gonotheca (H). F, G, I: Halecium delicatulum Coughtrey, 1876 — specimen MHNG-INVE- 26669, showing hydrothecae (F), stem internodes (G), and a female gonotheca (I). J, K: Halecium ovatum Totton, 1930 — fragment of stem showing branching pattern (J); female fonotheca (K). L, M: Antarctoscyphus elongatus (Jäderholm, 1904) — internodes with hydrothecae (L); gonotheca (M). N – P: Antarctoscyphus spiralis (Hickson & Gravely, 1907) — internode with hydrotheca (N); hydrothecal aperture in frontal view, showing intrathecal cusps (O); gonotheca (P). Q – S: Sertularella gaudichaudi (Lamouroux, 1824) — fragment of stem (Q); hydrotheca (R); female gonotheca (S). T, U: Symplectoscyphus cumberlandicus (Jäderholm, 1905) — fragment of stem (T); female gonotheca (U). V, W: Symplectoscyphus glacialis (Jäderholm, 1904) — fragment of stem (V); gonotheca (W). X – Z: Symplectoscyphus vanhoeffeni Totton, 1930 — fragments of stems from Stn. Ant. 06 / 2011 (X) and Stn. Ant. 12 / 2010 (Y); gonotheca from material from Stn. Ant. 06 / 2011 (Z). Scale bars: 10 µm (C), 100 µm (O), 300 µm (D, R), 400 µm (B), 500 µm (E – I, K – N, P, V – Z), 800 µm (J), 900 µm (T), 1 mm (A, Q, S, U).