Biofouling hydroids (Cnidaria: Hydrozoa) from a Tropical Eastern Pacific island, with remarks on their biogeography Author Calder, Dale R. Author Carlton, James T. Author Keith, Inti Author Ashton, Gail V. Author Larson, Kristen Author Ruiz, Gregory M. Author Herrera, Esteban Author Golfin, Geiner text Journal of Natural History 2022 2022-07-11 56 9 - 12 565 606 http://dx.doi.org/10.1080/00222933.2022.2068387 journal article 126956 10.1080/00222933.2022.2068387 5ca061c2-0cbb-4434-a28a-fc6c60e7ed7c 1464-5262 7012486 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.