Halecium lightbourni Calder 1990

• Main Author: Calder, Dale R.
• Format: Other/Unknown Material
• Language: unknown
• Published: 2019
• Subjects: Biodiversity; Taxonomy; Animalia; Cnidaria; Hydrozoa; Leptothecata; Haleciidae; Halecium; Halecium lightbourni; Myers; North Atlantic
• Online Access: https://zenodo.org/record/4581870; https://doi.org/10.5281/zenodo.4581870

Halecium lightbourni Calder, 1990 [1991a] Fig. 19a Halecium lightbourni Calder, 1990 [1991a]: 19, figs. 10, 11. Type locality. Bermuda: Flatts Inlet, 0.5 m (Calder 1990 [1991a]: 19). Material examined. Fort Myers Beach, on stranded Idiellana pristis, 01 March 2013, one colony, 3 mm high, without gonophores, coll. D. Calder, ROMIZ B4377. Remarks. Halecium lightbourni Calder, 1990 [1991a] is an infrequently reported and poorly known species, originally described from Bermuda. It has subsequently been reported from Panama (Calder & Kirkendale 2005), Martinique (Galea & Ferry 2015), and Cuba (Castellanos et al. 2018) in the western North Atlantic, and from Brazil (Nogueira et al. 1997; Grohmann et al. 2003; Oliveira et al. 2016) in the western South Atlantic. Hydroids of H. lightbourni resemble those of H. nanum Alder, 1859 in habit and in colony size (<1 cm high), but they differ most notably in lacking zooxanthellae. Among other characters differentiating H. lightbourni, colonies are less shrubby, hydrothecae tend to be narrower at the margin (129–160 μm vs. 147–182 μm), internodes of hydrocauli and branches are more slender at the nodes (65–86 μm vs. 84–89 μm), and large nematocysts (now considered pesudostenoteles rather than euryteles) are larger (8.3–8.9 μm long x 3.8–4.7 μm wide vs. 6.7–7.4 μm long x 3.1–3.8 μm wide) and somewhat different in shape (Calder 1990 [1991a]). The species has not been reported from pelagic Sargassum, a common substrate of H. nanum. The cnidome of H. lightbourni comprises microbasic mastigophores and small pseudostenoteles in addition to large pseudostenoteles (Calder 1990 [1991a]; Galea & Ferry 2015). When originally described (Calder 1990 [1991a]), only trophosomes of H. lightbourni were available for study. Gonosomes were discovered and described in material from Martinique by Galea & Ferry (2015). From their account, female gonothecae are sac-shaped to reniform, with a lateral aperture for two gonothecal hydranths. They thus differ from those of H. nanum, ...