Galapagos Species Database

Taxon category: Accepted

Note: Sertularella affinicostata differs from S. costata in having fewer ridges, barrel-shaped hydrothecae, and shorter, thicker cauline internodes. Misidentified specimens from French Frigate Shoals and the Galápagos Islands are now considered S. affinicostata. It shares hydrothecal ornamentation with other Sertularella species but differs in colony structure and size. Found in the Hawaiian Archipelago and eastern Pacific, it likely occurs elsewhere in the tropical Pacific (Calder & Faucci, 2021). Sertularella affinicostata was first reported as S. costata from the Galápagos Islands and later recognized as a new species in the Northwestern Hawaiian Islands. It differs from S. costata in ridge number, hydrotheca shape, and hydrocaulus structure. Found in 26% of Cocos samples, all sterile, this minute hydroid is a substrate generalist and potentially introduced via ship transport (Calder. et al. 2022). Holotype: Coll. K. Collins, ROMIZ B3339; Type locality: Galapagos Islands, Darwin Island, 26 january 1999; Paratype: ROMIZ B3409 Cousin Rock, ROMIZ B3418 Punta Espejo-Marchena, ROMIZ B5486 French Frigate Shoals (Calder & Faucci, 2021).

Origin: Cryptogenic

Distribution: Galapagos Islands, Wolf and Darwin islands (Calder et al. 2003, as Sertularella costata); Hawaiian archipelago, first record (Calder & Faucci, 2021).

• Calder, D. R Faucci, A. (2021) Shallow water hydroids (Cnidaria, Hydrozoa) from the 2002 NOWRAMP cruise to the Northwestern Hawaiian Islands. Zootaxa, 5085(1), 1-73.