PHYLOGENETIC ANALYSIS OF THE AMPHITRITINAE (POLYCHAETA, TEREBELLIDAE)

The phylogenetic relationships of the Amphitritinae (Polychaeta: Tereb ellidae) were studied using parsimony analysis of 22 external morpholo gical characters. To choose outgroups to polarize the characters, I ca rried out a preliminary analysis of the relationships of the four tere bellid subfamilies and the Trichobranchidae. The single most parsimoni ous tree from the analysis supports monophyly of the Terebellidae by t he presence of ventral glandular shields. However, this character is h omoplasious within the Terebellomorpha, and further evaluation of the Terebellidae is recommended. Artacama and Thelepus were chosen as outg roups for the analysis of amphitritine genera. The generic level analy sis yielded seven equally parsimonious trees, which are consistent in their topologies except for the relationships among seven genera in on e large clade. In all trees, Artacama is the sister taxon to a large c lade within the Amphitritinae; the Artacaminae is therefore synonymize d with the Amphitritinae, which is diagnosed by the presence of double rows of uncini. Within the Amphitritinae, the status of several monot ypic genera is questioned; plesiomorphic character states indicated by the analysis are discussed. The results presented are offered as work ing hypotheses of the relationships among amphitritine genera. The lar ge number of homoplasies indicated by the analysis emphasizes the need to further evaluate these hypotheses using additional characters. Wit h a robust phylogenetic hypothesis of amphitritine relationships, a re -classification of the group based on apomorphic character states can be undertaken, and questions regarding the evolution of morphological characters, reproductive modes, or biogeographical patterns can be pro perly addressed. (C) 1995 The Linnean Society of London