Halecium

Galea, Horia R., 2010, Additional shallow-water thecate hydroids (Cnidaria: Hydrozoa) from Guadeloupe and Les Saintes, French Lesser Antilles, Zootaxa 2570, pp. 1-40 : 11

Halecium sp.

(fig. 3P–S)

Material examined. Stn.8: 0 5.12.2009, 17 m—a small, sterile colony composed of several minute erect stems to 3 mm high, on basal part of stem of Macrorhynchia philippina Kirchenpauer, 1872 . Stn.9: 21.11.2009, 21 m—a sterile colony with stems to 2 mm high, on basal part of stem of Sertularella diaphana ( Allman, 1885) , morphotype 2.

Description. Colonies small, to 3 mm high, monosiphonic, unbranched or sparingly branched, arising from creeping hydrorhiza. Stems geniculate, composed of long (520–960 µm), straight to slightly curving internodes; diameter at node 60–75 µm. Distal end of internode slightly expanded, with a hydrotheca and an apophysis lateral to it (fig. 3R), occasionally with a secondary apophysis given off from opposite side (fig. 3Q). Hydrotheca sessile, shallow (30–35 µm), widening from base (120–135 µm wide) to rim (140–155 µm wide), but not everted; margin entire; occasionally renovated once. Hydranths with about 18 tentacles. Zooxanthellae likely absent from coenosarc. Nematocysts: microbasic mastigophores (6.3–6.5 × 1.8–2.0 µm) and probably microbasic euryteles (6.5–6.7 × 3.1–3.2 µm). Gonothecae absent.

Remarks. This species is unidentifiable in the absence of (female) gonothecae. Additional, fertile material is required for a proper identification.

2. The discharged capsules of H. fjordlandicum were incorrectly referred by Galea (2007) to as macrobasic mastigophores. Upon careful reinspection of available photomicrographs, it appears that their thread is isodiametric throughout, and should be correctly referred to as holotrichous isorhizas.