A comparative study of the hypopharynx in Dictyoptera (Insecta)

The exoskeletal morphology of the hypopharynx is documented for and compared between nine species of Dictyoptera that represent most of its principal lineages (seven cockroaches, one mantodean, and the ‘basal’ termite Mastotermes darwiniensis). In addition, hypopharyngeal morphology in Dictyoptera is compared with that in the zygentoman Thermobia domestica and to the extent possible with that in the embiopteran Embia ramburi (based on data from the literature). This comparison also considers the musculature (using data from the literature) and aims at identifying corresponding parts between Dictyoptera and the two other taxa (especially Thermobia). 19 hypopharyngeal characters are defined that are potentially informative on phylogenetic relationships in Dictyoptera, and their preliminary phylogenetic implications are discussed. However, there is little congruence among the characters from the hypopharynx, and groupings supported by the various characters are mostly in conflict with previous studies on dictyopteran phylogeny. Yet, the presence of a small lateral apodeme may support the widely accepted monophyly of Blattodea (including termites).