A NEW MARINE SPECIES OF SMITHSONIDRILUS (OLIGOCHAETA, TUBIFICIDAE) FROM THE FLORIDA KEYS

Smithsonidrilus exspectatus, new species, is described from barely sub tidal sediments at Pigeon Key (near Marathon) and Bahia Honda, souther n Florida. It appears phylogenetically intermediate between Smithsonid rilus hummelincki and the most apomorphic group within the genus (Smit hsonidrilus marinus, Smithsonidrilus involutus, Smithsonidrilus weston i, and Smithsonidrilus multiglandularis); all these species show a nor thwest Atlantic distribution. The new species has the same kind of spe rmatheca as, but a less elaborate copulatory sac (pseudopenis) than, t hose of the species in the S. marinus group. The dilated, heavily musc ular ejaculatory duct appears to be an autapomorphy of S. exspectatus.