Candelabrum penola Manton 1940

Candelabrum penola (Manton, 1940)

(Pl. 1M–Q)

Myriothela penola Manton, 1940: 256, figs 1–6, pl. 1 figs 10, 11, 14, pl. 2 figs 15–21, pl. 3 figs 22–26, 28, pl. 4 figs 29–34.

Material examined. Stn. SHO — 16.ii.2011, Ant.34/2011 (43 m): a 60 cm tall individual, blastostyle region ca. 13 cm high and 5.5 cm wide, tentacle region ca. 47 cm long and 3.5–4.0 cm wide (measurements taken on fixed specimen); Ant.35/2011 (43 m): a 50 cm high individual, blastostyle region 7–8 cm long, ca. 7 cm wide, tentacle region ca. 43 cm long and 4–5 cm wide (measurements taken on fixed specimen) (MHNG-INVE-79800).

Description. Solitary polyps of worm-like appearance, attached to the naked, horny axes of pennatulacean anthozoans. Body composed of three parts: the foot, a blastostyle-bearing region, and a distal body portion. Foot totally hidden by blastostyle region upon body torsion caused by tight attachment around the filiform substrate; only several long, extensible, adhesive tentacles capped by chitinoid disks are seen in the more exposed parts of the lower body. Blastostyle region comparatively swollen with respect to the tentacle-bearing part; richly covered with up to 3.5 cm long blastostyles; the latter, tubular prolongations of the body wall, bearing gonophores on their lower halves and a number of lobes distally; each lobe provided with a few short, conical, capitate tentacles; distalmost lobes often continuous with each other; mid-region of some blastostyles with gonophores co-occurring with small, isolated tentaculate lobes. Basalmost blastostyles carrying proximally much longer, adhesive tentacles, providing additional fixation points of the hydroid to its substrate. Gonophores, up to 25 per blastostyle, sessile, and spherical. Remainder of body much longer than blastostyle region, tapering gradually towards apex where it bears the mouth; surface set with densely-packed, small (ca. 2 mm high), capitate tentacles. Gastric cavity lined with densely-folded endoderm.

Remarks. For a description of this species based on a comprehensive histological study, see Manton (1940).

Geographical distribution. All known records are from the western side of the Antarctic Peninsula, viz. Argentine Islands (Manton 1940), Bellinghausen Sea (Peña Cantero in press), and South Shetland islands (present study).