First record of Sphaerodoridae (Phyllodocida: Annelida) from hydrothermal vents

Sphaerodoropsis anae n. sp. is described from sediments near active hydrothermal vents along the northern part of the Pacific Antarctic ridge, adjacent to the Easter Microplate. Two distinct features principally characterize Sphaerodoropsis anae n. sp., the presence of a well-developed proventricle, quite similar to the proventricle found in Syllidae, and bi-dentate compound chaetae with spinulation. It is also characterized by the presence of four macrotubercles per transverse row, with the lateral ones pear-shaped and the median macrotubercles spherical and smaller. Types of other Sphaerodoropsis species were examined and Sphaerodoropsis biserialis (Berkeley & Berkeley, 1944) also has compound chaetae with spinulation. This feature was not previously described in this species. Some comments about the current systematics of Sphaerodoropsis and Sphaerodoridae are made, as well as a discussion of the proventricle.