Eight species of scaled polychaetes are reported from hydrothermal vents of the Guaymas Basin in the Gulf of California:
Neoleanira racemosa in the Sigalionidae and seven species of Polynoidae, including two new species,
Bathykurila guaymasensis, in Macellicephalinae, and
Macellicephaloides alvini, in Macellicephaloidinae. The latter genus and subfamily are reviewed, and a Key to the seven species in the genus is provided. Included are additional records of some species of Polynoidae from hydrothermal vents from the Galapagos and 21°N in the eastern Pacific, as well as seep-sites in the Gulf of Mexico Florida Escarpment and off Louisiana.