Halecium sp.

Calder, Dale R., Carlton, James T., Keith, Inti, Ashton, Gail V., Larson, Kristen, Ruiz, Gregory M., Herrera, Esteban & Golfin, Geiner, 2022, Biofouling hydroids (Cnidaria: Hydrozoa) from a Tropical Eastern Pacific island, with remarks on their biogeography, Journal of Natural History 56 (9 - 12), pp. 565-606 : 588

Halecium sp.

( Figure 6d )

Material examined

Chatham Bay, dock 004, no coordinates, 1 colony fragment, on Macrorhynchia philippina , 5 mm high, without gonothecae, coll. G. Ashton, #266335.

Remarks

Because it lacked gonophores, especially those of the female, this hydroid could not be positively identified. The trophosome fragment did not appear to correspond to any of the species from the Tropical Eastern Pacific assigned by Fraser (1938a, 1938b, 1938c, 1948) to Halecium Oken, 1815 . Moreover, Nemalecium lighti ( Hargitt, 1924) , known from the region ( Hickman 2008; Banks et al. 2009; Calder et al. 2019, 2021), was discounted as a possibility because no nematodactyls or large pseudostenotele nematocysts were observed in the available material. The hydroid has been assigned here simply to Halecium sp.

Reported distribution

Cocos Island: first record.

Figures

Figure 6. Leptothecata: Obeliidae, Haleciidae, Sertularellidae and Sertulariidae. (a) Obelia microtheca: hydrocaulus with two pedicels and hydrothecae, #240607. (b) Obelia microtheca: part of hydrocaulus with long pedicel and a hydrotheca, #240607. (c) Obelia microtheca: part of hydrocaulus and base of a pedicel with a gonotheca, #240607. (d) Halecium sp.: part of hydrocaulus with hydrothecae and base of a branch, #266335. (e) Sertularella affinicostata: stolon and stem with five hydrothecae, #240592. (f) Sertularella affinicostata: part of stem with two hydrothecae, #240592. (g) Tridentata borneensis: base of a stem with two pairs of hydrothecae, #240634. (h) Tridentata borneensis: distal end of a stem with two pairs of hydrothecae, #240634. (i) Tridentata borneensis: gonotheca, #266336. Scale bars: a, i = 0.2 mm; b–d, f–h = 0.1 mm; e = 0.5 mm.