Zoological Studies

Vol. 42 No. 1, 2003

A New Species of Megalomma Johansson, 1927 (Polychaeta: Sabellidae: Sabellinae) from Taiwan, with Comments on Sabellid Dorsal Lip Classification

Kirk Fitzhugh

Research and Collections Branch, Los Angeles County Museum of Natural History, 900 Exposition Boulevard, Los Angeles, California 90007, USA

Kirk Fitzhugh (2003) A new species, Megalomma cinctum, is described from the intertidal zone of Hungtou Yu, also known as Orchid Island, located off the southeast coast of Taiwan. The species is most similar to M. coloratum (Chamberlin), M. modestum (Quatrefages), M. quadrioculatum Willey, M. roulei (Gravier), and M. splendidum (Moore), each of which has 1 pair of dorsalmost compound eyes on the radioles, sometimes with additional eyes on the 2nd and 3rd pairs of radioles, and the middorsal margins of the peristomial collar are fused to the lateral margins of the fecal groove, forming dorsolateral pockets. Megalomma cinctum is distinct from these species by the presence of a narrow, white, transverse band on setiger 2, and sometimes also on setiger 3. The number of pairs of radiolar eyes in M. cinctum is much more variable than has been reported in other species, and is strongly correlated with body size. Additional variability in the species is also reported for the number of pairs of radioles, peristomial collar shape, number of thoracic setigers, occurrence of the white transverse bands on setigers 2 and 3, and pigmentation patterns on the crown and thorax. The species is dioecious, but asexual reproduction also occurs by scissiparity. The description of M. cinctum also includes details on the internal construction of the dorsal lip radiolar appendages, necessitating an emendation of the definition of the genus. A brief survey is also presented of dorsal lip internal construction within the Sabellidae, and the implications of those findings for the determination of cladistic relationships among Sabellinae genera are discussed.

Key words: Annelida, Fan worm, Sabellid, Systematics, Cladistics.

*Correspondence: E-mail: kfitzhug@nhm.org