Four new species of fan worms (Polychaeta: Sabellidae) from worldwide localities

Abstract

Four new species of soft-bottom sabellid polychaetes are described and illustrated. Branchiomma costaricensis n. sp. is described from 31 m depth off Isla del Coco, Costa Rica; Dialychone arabica n. sp. from 105 m depth in the Arabian Sea; Dialychone blakei n. sp. from 487 m depth off Louisiana in the Gulf of México and Paradialychone harrisae n. sp. from 30 m depth in southern California. Branchiomma costaricensis n. sp. is characterized by having microstylodes with the median pair 1.5 times longer than neighbouring pairs, thoracic uncini with two rows of teeth above the main fang, an unspotted body and large interramal eyespots. Dialychone arabica n. sp. has the anterior peristomial ring lobe exposed beyond the collar and a pre-pygidial depression occupying eight segments. In D. blakei n. sp., the anterior peristomial ring lobe is not exposed beyond the collar, the pre-pygidial depression occupies the last four segments and the posterior segments possess thin elongate, narrowly hooded chaetae. Paradialychone harrisae n. sp. differs from the other species of the genus in having the anterior peristomial ring lobe bilobed and exposed beyond the collar, a rectangular ventral collar shield and paleate chaetae with a long mucro.

Keywords

• sabellidae
• branchiomma
• dialychone
• paradialychone