SYSTEMATIC AND ECOLOGICAL CHARACTERISTICS OF PARALVINELLA-SULFINCOLA DESBRUYERES AND LAUBIER, A NEW POLYCHAETE (FAMILY ALVINELLIDAE) FROM NORTHEAST PACIFIC HYDROTHERMAL VENTS

Polychaetes of the family Alvinellidae (Terrebellida) are endemic to hydrothermal vent communities. A new species from the Juan de Fuca and Gorda ridges in the Northeast Pacific is described; aspects of its buccal appendages, segment number, and uncini placement are unique. Because of initial confusion with a sympatric species, Paralvinella palmiformis Desbruyeres and Laubier, protein mobilities were examined to differentiate the species electrophoretically with reference to a third alvinellid, Alvinella pompejana. Among the 17 loci scored, fewer than a quarter of the alleles were present in the two Paralvinella species; Paralvinella sulfincola n.sp. has several diagnostic allozymes. This new species inhabits tubes on the sides of active smoker chimneys and migrates upward as the chimney grows. Individuals are recorded within 1 cm of hydrothermal fluids at temperatures in excess of 300-degrees-C; the species appears to have several molecular adaptations to high ambient temperatures. The Alvinellidae form a fascinating group within which to study phylogenetic and selective processes.