A new genus and species of monostiliferous hoplonemertean colonizing an inchoate hydrothermal field on Juan de Fuca Ridge

A new genus and species of monostiliferous hoplonemertean, collected from a hydrothermal vent on the Juan de Fuca Ridge in the northeastern Pacific, is described and illustrated. A significant feature of the species, not reported for any other nemertean, is the occurrence of lipid-like globules associated with large numbers of mitochondria in cells that are distributed in irregular groups immediately below the body wall musculature. Ecological evidence suggests that the nemertean, the first described from any hydrothermal vent system, is both an early colonizer of vents and vent endemic.