Phylogenetic analysis of dorid nudibranchs (Gastropoda : Doridacea) using the mitochondrial 16S rRNA gene

A 400 bp region of the mitochondrial 16S rRNA gene was sequenced in 24 dori d nudibranch species. In addition a dendronotid nudibranch and a notaspidea n were sequenced for use as outgroup. The sequences were characterized with respect to spatial variation and secondary structure. The data were analys ed using parsimony, exploring the effects of alignment and weighting on the optimal hypothesis, and a distance analysis was also performed. The optima l hypotheses differed between the analyses, although the clades with substa ntial bootstrap proportions were usually present in all cases. These clades are in general congruent with existing classifications, and correspond to relationships within family level taxa. The relationships between these cla des were inconclusive and the monophyletic status of higher taxa of particu lar interest (e.g., Eudoridoidea, Anadoridoidea) could neither be corrobora ted nor dismissed.