Peristomatic structures in Scutigeromorpha (Chilopoda): a comparative study, with new characters for higher-level systematics

Structural details of the areas around the mouth opening in centipedes (Chilopoda) have not previously been studied comparatively, though descriptions of single representatives of the major groups indicate conspicuous variability. In order to clarify its phylogenetic significance, the roof of the preoral chamber (epipharynx) and its bottom (hypopharynx) have been examined for 17 species that sample 11 genera of Scutigeromorpha. The survey by light and scanning electron microscopy includes representatives of each of the major subgroups (Scutigerinidae, Pselliodidae, Scutigerinae and Thereuoneminae). The detailed morphology of the peristomatic areas is similar in all species. The three major subgroups Scutigerinidae, Pselliodidae and Scutigeridae are each distinguished by the structure of the lateral rows of labral bristles and details of the epipharyngeal sensilla. By comparison to pleurostigmophoran chilopods, several characters of the hypopharynx and epipharynx can be identified as autapomorphic for Scutigeromorpha. The pselliodid Sphendononema shares a few apparent synapomorphic characters with Scutigeridae to the exclusion of the Scutigerinidae, providing additional morphological support for Scutigerinidae being sister group of all other Scutigeromorpha.