Eudendrium, Ehrenberg, 1834

Soto, Joan J. & Peña, Álvaro L., 2019, Benthic hydroids (Cnidaria, Hydrozoa) from the Weddell Sea (Antarctica), Zootaxa 4570 (1), pp. 1-78 : 14

Eudendrium sp.2

( Fig. 3j )

Material examined. ANT XXI/2: PS65/248, one colony, c. 80 mm high, with male gonophores.

Remarks. This species is characterized by having a strongly polysiphonic stem, up to 80 mm high, with smooth perisarc. Only 8–9 polyps remain in the material examined. Male gonophores are mono- or bichambered, up to nine per polyp ( Fig. 3j ). The cnidome consists of microbasic euryteles of two size classes: the smaller [range 10.5–12.0 x 5.0–5.5 µm, mean 11.3±0.5 x 5.1±0.2 µm (n=15)], abundant on tentacles, and the larger [range 32.0– 35.5 x 16 –18.0 µm, mean 33.5±1.4 x 17.1±0.6 µm (n=16)] are scarce on the hypostome. The present material agrees, in the shape of the colony and the size of the nematocysts, with the material described as Eudendrium sp.1 by Peña Cantero (2009) and reported anew by Peña Cantero (2014a). As stated by this author, the material could be conspecific with Eudendrium cyathiferum Jäderholm, 1904 , but the cnidome of Jäderholm’s species remains unknown and further investigations are needed regarding this issue.

Ecology and distribution. Material presumably belonging to this species reported at depths between 103 (Peña Cantero 2009, as Eudendrium sp.) and 699 m ( Peña Cantero 2014a, as Eudendrium sp. 1); present material at 286– 287 m. Previously known from the Balleny Islands (Peña Cantero 2009) and Queen Mary Coast ( Peña Cantero 2014a), in East Antarctica. Present contribution constitutes the first evidence of the species from both the Weddell Sea and West Antarctica, pointing to circum-Antarctic distribution.

Figures

FIGURE 3. a–f Hydractinia dendritica: a–b general view of the colony; c detail of spines; d gastrozooids and dactylozooid (arrow); e gonozooid with gonophores; f dactylozooid (arrow). g Eudendrium antarcticum: female gonophore. h Eudendrium generale: female gonophore. i, k Eudendrium scotti: i gonozooid with male gonophores; k colony. j Eudendrium sp.2: gonozooid with male gonophores.