Ref ID : 6584
Christer Erseus; Phylogenetic analysis of the aquatic Oligochaeta under the principle of parsimony. Hydrobiologia 155:75-89, 1987
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Phylogenetic relationships between five subfamilies of Tubificidae and ten other families of microdrile oligochaetes were estimated by a Wanger parsimony analysis uing PAUP (Phyogenetic Analysis Using Parsimony, by D.L. Swofford). As the apomorph character state is ambiguous for some characters, different assumptions of directionality as well as deletions of some characters are tested in a number of analyses. A general pattern is evident from the study; (1) the majority of the aquatic families are members of a large monophyletic group (the order Tubificida in a somewhat restricted sense) defined by the shared possession of atria (generally with well developed external prostate glands), but the family Tubificidae is paraphyletic within this group; (2) the Enchytraeidae appear to form a second group (the 'Enchytraeida') together with the exclusively marine Capilloventridae and Randiellidae, all three families characterized by the anterior location of the spermathecae; (3) the Haplotaxidae are a plesiomorph family, which stands out as a branch of its own and constitutes the 'ancestral' part of a group comprising also all the megadriles (the Haplotaxida). However, monophyly of the Haplotaxida is likely only if the haplotaxid octogonadial condition is assumed to be derived from the tetragonadial condition characterizing most microdriles, a situation not envisaged by previous authors. The implications of the parsimony method are briefly discussed.