Halecium, Oken, 1815

Calder, Dale R., 2019, On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA, Zootaxa 4689 (1), pp. 1-141: 72

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Halecium  sp.

Figs. 19e, fView FIGURE 19

Material examined. Southwest Florida Shelf, middle shelf west of Gasparilla Island, 26°45.86’N, 83°21.44’W, 50 m, 18 July 1981, triangle dredge, one colony fragment, 3.9 cm high, without gonophores, coll. Continental Shelf Associates, ROMIZ B1594.— Sanibel Island , beach at Lighthouse Point, 26°26’58”N, 82°01’04.5”W, detached and stranded on beach, 21 March 2018, 22° C, 34.5‰, one colony, 7 cm high, with male gonophores, coll. D. Calder, ROMIZ B4381GoogleMaps  .

Remarks. These hydroids resemble the trophosomes of several species of Halecium Oken, 1815  that have been reported from the Gulf of Mexico ( Calder & Cairns 2009), including H. halecinum ( Linnaeus, 1758)  , H. beanii ( Johnston, 1838)  , H. sessile Norman, 1867  , H. macrocephalum Allman, 1877  , and H. bermudense Congdon, 1907  . In lacking female gonophores, the specimens cannot be reliably identified to species. Colonies were strongly polysiphonic, with alternate and predominantly pinnate side branches; hydranths bore 20+ tentacles and the cnidome comprised both pseudostenoteles (10.2–12.0 long x 5.4 – 7.0 μm wide) and microbasic mastigophores (ca. 6.0 long x 1.8 μm wide).