Harmful touch: tarsal palisades as unique tools of predation in biting midges (Diptera: Ceratopogonidae)

摘要

Tarsal palisade setae present on the hind and mid legs of 26 genera of biting midges were studied using light and scanning electron microscopy. They are arranged in single, double or triple rows on the hind and sometimes mid tarsomeres 1 and 2 in both sexes. The grooved palisade setae of most genera except Alluadomyia, Brachypogon, Ceratopogon and Ceratoculicoides are inserted in sockets which elongate into a tongue-like extension basally fused with two enlarged microtrichia. Morphologically similar tarsal setae occur in the Forcipomyiinae and Dasyheleinae, but they are distributed irregularly. This study shows that reinforced tarsal setae probably evolved independently on the tarsi of biting midges, in the lineage of originally parasitic Forcipomyiinae and Dasyheleinae and within the lineage of predatory Ceratopogoninae. The setae arranged in a palisade evolved once, most probably within the primitive tribe Ceratopogonini as an evident adaptation to the hunting of other insects.