Comparative morphology of the raptorial leg in thread-legged bugs of the tribe Metapterini Stål, 1859 (Hemiptera, Heteroptera, Reduviidae, Emesinae)

Assassin bugs (Hemiptera, Heteroptera, Reduviidae) have diverse and complex morphological and behavioral adaptations for prey capture. Several of these morphological adaptations occur on the proleg. The prolegs of Emesinae are typically raptorial and they are used for grooming, grasping and hunting prey. Several morphological characters that define Emesinae as a group are found on the proleg, such as the anterior opening of the acetabula, the elongation of the procoxa, and the lateral (campaniform) sensilla on the protibia. Metapterini comprises 28 genera and approximately 280 described species, and are characterized by a conspicuous basal process of the anteroventral series of the profemur, and highly modified pretarsal structures. In this study, structures of the proleg are documented for 13 genera of Metapterini, using stereomicroscopy and scanning electron microscopy (SEM). Detailed descriptions and digital macrophotographs are provided for most of the genera for the first time, and from this morphological documentation 38 phylogenetic characters are coded, presented as a data matrix, and analyzed cladistically, and their potential usefulness for resolving relationships among Metapterini is discussed.