CLADISTIC RELATIONSHIPS IN THE FAN WORM GENUS LAONOME MALMGREN, AND RELATIONSHIPS AMONG SABELLINAE GENERA
Fitzhugh, K.
Research & Collections Branch, Los Angeles County Museum of Natural History, 900 Exposition Boulevard, Los Angeles, California 90007, USA
The Sabellidae genus Laonome, originally described by Malmgren (1865), has for most of its history been considered a very uniform taxon. The genus currently contains six species. The two features most often defining the genus include: 1) the absence of thoracic neuropodial companion setae, and 2) the absence of handles on thoracic and abdominal uncini. Within the past 10 years, cladistic analyses have suggested that these instances of absence are synapomorphies and both can be considered as losses in the genus. Cladistically, Laonome is an apomorphic member of the subfamily Sabellinae, and sister group to Amphiglena Claparède and a newly described genus. One species, however, L. albicingillum Hsieh from Taiwan, has been described with companion setae. Results of my recent revision of Laonome include an additional three species, one of which has companion setae. A general review of the genus will be presented. In addition to companion setae, variability is also seen in the occurrence of dorsal lip radiolar appendages, originally thought to be absent in the genus. I will present results of cladistic analyses of the nine species in Laonome, and reevaluate relation of the genus to other Sabellinae. Support for the monophyly of Laonome will be discussed, as well as the occurrence of other characters readily supporting monophyly. While the genus might not appear as homogeneous as once regarded, the basis for splitting species among two or more genera cannot be substantiated.