Polynoidae and Sigalionidae (polychaeta) from the Guaymas Basin, with Descriptions of Two New Species, and Additional Records from Hydrothermal Vents of the Galapagos Rift, 21°n, and Seep-sites in the Gulf of Mexico (florida and Louisiana)

•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*^^ in the eastern Pacific, as well as seep-sites in the Gulf of Mexico Rorida Escarpment and off Louisiana. A small collection of scaled polychaetes from the Guaymas Basin in the Gulf of California or the Sea of Cortez was sent to me for study by J. F. Grassle. Hot vents and hydrocarbon seeps were discovered in this area in 1980 and sampled in 1982 during dives of the submersible DSRV^/v/« (Lonsdale 1984, Grassle 1986). The area, a continuation of the East Pacific Rise into the Gulf of California, is covered by a thick layer of pelagic muddy sulfide sediment. The study site consists of mounds of hydrothermal precipitates in the spreading center troughs at about 2000 meters. The fauna included large numbers of the giant vestimentiferans, Rifiia, giant clams, such as Calyptogena pacifica, nuculanid bivalves, alvinellid polychaetes, as Pamlvinella grasslei, and flufly mats of the large bacterium Beggiatoa. Eight species of scaled polychaetes are reported herein from the Guaymas Basin, seven of them belonging to the Polynoidae and one to the Sigalionidae: Neoleanira racemosa (Fauchald), previously reported from the Guaymas Basin by Fauchald (1972, as Sthenolepis). Of the polynoid species, five were previously described by me from other vent areas: one, Branchiplicatus cupreus, from the tropical eastern Pacific at 21°N; one, Lepidonotopodium riftense, the same area and the Galapagos Rift; and three, Branchinotogluma grasslei, B. sandersi, and Levensteiniella kincaidi, from the above two areas and also the Explorer and Juan de Fuca Ridges. The other two polynoid species are described below as new species: Bathykurila guaymasensis, in Macellicephalinae, and Macellicephaloides alvini, in Macellicephaloidinae. The specimens were collected during Alvin dives in 1982 and 1985, in washings from rock with •worms, Bead Experiment washings, washings from Rock Chimney, washings from Rifiia, Calyptogena, and alvinellid polychaetes, from Box cores taken on the slopes of the mounds, some with numerous nuculanid bivalves. Some additional records of previously described vent fauna are included in this report, such as Branchipolynoe symmytilida, removed from some Galapagos mussels and sent to me in July 1985 by J. F. Grassle. VOLUME 102, NUMBER 1 155 Also, specimens oíBranchipolynoe seepensis were removed by Ruth Turner from Gulf of Mexico mussels collected in the seep-sites at the Florida Escarpment and sent to me in October 1986, by Barbara Hecker. An additional specimen of this species was collected in May 1987, by the US Navy submarine NR-1 and R/V Gyre and sent to me by T. H. Perkins. Additional vent polynoids from the Galapagos and the eastern Pacific Rise at 2rN, collected during Alvin dives in 1979 and 1982, chiefly among fauna in washings from mussels and crab traps, were sent to the Smithsonian Sorting Center for further sorting and transferred to me in December 1987. They supplement my previous studies on this group. Types and additional specimens are deposited in the collections of the Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution