Molecular phylogeny confirms Conochilidae as ingroup of Flosculariidae (Rotifera, Gnesiotrocha)

We test the hypothesis that conochilid rotifers represent an independent family‐level taxon within Superorder Gnesiotrocha, by analysing their phylogenetic position based on the 18S rDNA sequence of a large number of representatives of this taxon and its putative relatives. Both Bayesian and maximum likelihood analysis confirm a monophyletic clade of all gnesiotrochans with strong branch supports. Within Gnesiotrocha, Conochilidae form a strongly supported clade with representatives of all but some genera of Flosculariidae. These results refute Conochilidae as separate family‐level taxon within Gnesiotrocha. This finding is also supported by a phylogenetic analysis using morphology, in particular new observations on trophi morphology. Conochilid rotifers are likely specialized Flosculariidae, which evolved to a planktonic lifestyle and reduction of coloniality within the group, in contrast to other Flosculariidae. Furthermore, our analysis reveals that two genera of Flosculariidae, Beachampia and Limnias , form a single, strongly supported clade in a sister‐group relation to a clade consisting of representatives of Order Collothecacea. The present results, both regarding position of the conochild rotifers and of two genera of Flosculariidae, highlight the need for a more extensive analysis of relationships within Gnesiotrocha.