Terminology for the setae and scales on the thoracic pleurites of the blackflies (Diptera, Simuliidae)

We studied the setae and scales located on the lateral sclerites of the thorax in 27 blackfly species (Diptera, Simuliidae) by scanning electron and optical microscopy. For the first time, it was shown that some thoracic setae are modified and have serrations. The size and number of serrations in the modified setae vary between blackfly species. The antepronotal setae of Gymnopais trifistulatus have a few small serrations, those of Simulium erythrocephalum are larger, and in S. maculatum and S. pusillum, have many well-developed serrations; Prosimulium macropyga has serrate setae on the postpronotum, while Simulium maculatum and S. pusillum have narrow scales. We proposed a terminology for the setae and scales on the thoracic pleurites of the blackflies (antepronotal setae, postpronotal setae and scales, etc.). The body chaetome of evolutionarily advanced groups (species of the genus Simulium) is formed by both scales and setae of various types, while in archaic groups (Prosimulium, Helodon) setae with varyingly developed serrations predominate.