A taxonomic revision of the Hydroides species (Polychaeta: Serpulidae) from the Eastern Pacific Ocean is presented. Twenty-one taxa are described, of which two are widespread (H. diramphus Mörch, 1863 and H. elegans (Haswell, 1883)) and four are Amphiamerican (H. alatalateralis (Jones, 1962), H. gairacensis Augener, 1934, H. salazarvallejoi Bastida-Zavala & Ten Hove, 2003, and H. sanctaecrucis Kroyer [in] Mörch, 1863). Three species are new to science: Hydroides deleoni n. sp., H. panamensis n. sp. and H. trompi n. sp. Morphometric comparisons between H. brachyacanthus Rioja, 1941, H. deleoni n. sp., and H. similis (Treadwell, 1929), between H. chilensis Hartmann-Schröder, 1962, H. cruciger Mörch, 1863 and H. panamensis n. sp., and between H. recurvispina Rioja, 1941 and H. trompi n. sp. are given. Three specific names are placed into synonymy: Hydroides californicus Treadwell, 1929, H. intereans (Chamberlin, 1919) and H. pacificus Hartman, 1969. A key to all species from the Eastern Pacific Ocean is given.
Eastern Pacific warm temperate to tropical