Phylogeny of cockroaches (Insecta, Dictyoptera, Blattodea), with placement of aberrant taxa and exploration of out-group sampling

We addressed the phylogeny of cockroaches using DNA sequence data from a broad taxon sample of Dictyoptera and other non-endopterygotan insect orders. We paid special attention to several taxa in which relationships are controversial, or where no molecular evidence has been used previously: Nocticolidae, a family of small, often cave-dwelling cockroaches, has been suggested to be the sister group of the predaceous Mantodea or of the cockroach family Polyphagidae; Lamproblatta, traditionally placed in Blattidae, has recently been given family status and placed as sister to Polyphagidae; and Saltoblattella montistabularis Bohn, Picker, Klass & Colville, a jumping cockroach, which has not yet been included in any phylogenetic studies. We used mitochondrial (COI + COII and 16S) and nuclear (18S and 28S) genes, and analysed the data using Bayesian inference (BI) and maximum likelihood (ML). Nocticolidae was recovered as sister to Polyphagidae. Lamproblatta was recovered as sister to Blattidae, consistent with the traditional placement (not based on phylogenetic analysis). However, because of the limited support for this relationship and conflict with earlier morphology-based phylogenetic hypotheses, we retain Lamproblattidae. S. montistabularis was consistently placed as sister to Ectobius sylvestris Poda (Blaberoidea: Ectobinae), indicating that the saltatorial hindlegs of this genus are a relatively recent adaptation. Isoptera was placed within Blattodea as sister to Cryptocercidae. Nocticolidae + Polyphagidae was sister to Isoptera + Cryptocercidae, and Blaberoidea was sister to the remaining Blattodea.