Systematic and ecological characteristics of Paralvinella sulfincola Desbruyères 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 Desbruyères 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 °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.