Harpactorinae, Harpactorini, and Apiomerini
With ca. 2300 species, Harpactorinae are the largest subfamily within Reduviidae. Comprising 289 genera and 2003 species, Harpactorini is the largest tribe in Harpactorinae. Members of Harpactorini include the familiar wheel bug (Arilus Hahn, 1831), and leafhopper assassin bug (Zelus renardii). Among the genera of Harpactorini, Zelus is unique in possessing glands and associated setae on the front tibiae, which secrete sticky substances onto the front legs that are used for prey capture. The evolution of morphological characters and associated behaviors are unknown. It is also unclear whether similar morphology and behavior exist in other genera of Harpactorini. Records are anecdotal, with Pselliopus Bergroth, 1905 and Cosmoclopius Stål, 1866 being recorded to have secretory setae on the front legs. Apart from the unusual predatory strategy in Zelus, a number of genera exhibit modifications of the pronotum. Simple modifications include spines or tubercles on the posterior pronotal lobe as seen in Z. tetracanthus, Repipta Stål, 1859 and Ploeogaster Amyot & Serville, 1843. Exaggerated modifications are the strongly raised and divided posterior pronotal lobe in Ulpius Stål, 1865 and wheel-like pronotum in Arilus. Such exaggerated modifications have only been observed in Harpactorini and no comparable examples are found in other subfamilies. Phylogenetic relationships between the genera of Harpactorini are unexplored. The tribe may be non-monophyletic with respect to Rhaphidosomini and Tegeini.