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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
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