Redescription of Mesochaetopterus selangolus (Polychaeta: Chaetopteridae), Based on Type Specimens and Recently Collected Material from Morib Beach, Malaysia

Rullier constructed the monotypic genus Sasekumaria within the family Chaetopteridae in 1976. I studied the type specimens and recently collected material and transferred Sasekumaria selangola to the genus Mesochaetopterus established by Potts in 1914. Mesochaetopterus selangolus is characterized by two middle segments with extended notopodia, associated feeding organ, a J-shaped tube, and the porous end of the tube. The species closely resembles M. japonicus Fujiwara, 1934. Mesochaetopterus selangolus can be differentiated from M. japonicus by the number of notochaetae in the middle and posterior region, the number of teeth on the uncinal plates of the middle and posterior region, the morphology of the anal region, and the structure of the tube. Mesochaetopterus selangolus is compared with other species of the genus and diagnostic keys are provided