Some Comments on the Taxonomy of the Peanut Worms (Annelida: Sipuncula) in Japanese Waters Toward a Future Revision

Abstract

The history of Japanese sipunculan taxonomy is briefly reviewed here. Some possible examples of cryptic speciation are also given for sipunculans with wide geographic distribution and records far from Japanese waters, as strongly suggested by recent molecular phylogenetic analyses: these include Japanese populations referred to as Sipunculus nudus, Siphonosoma cumanense, Themiste hexadactyla, Antillesoma antillarum, Aspidosiphon laevis, and Phascolosoma perlucens. Future taxonomic revisions of these species, which may be inevitable, would further our understanding of sipunculan diversity in Japanese waters. Reference to Siphonosoma australe takatsukii, recently recorded from the Ryukyu Islands, is also made.