Intra- and inter-familial homologies of maxillary palpal sensilla of larval Simuliidae (Diptera: Culicomorpha)

Abstract

Light and scanning electron microscopy was used to examine innervation and external structure of maxillary sensilla of larvae of various species of Prosimulium, Twinnia, Gymnopais, Crozetia, Stegopterna, Cnephia, Metacnephia, Gigantodax and Simulium, with emphasis on palpal sensilla. For the palpus, 12 apical sensilla of six distinct morphological types are described, named, and homologies established within the Simuliidae. First instar larvae of Prosimulium, Twinnia, and Gymnopais have a linear array of apical sensilla plus apical spicules, both characters synapomorphic for these three taxa. Prosimuliini genera possess cuticular plates around the palpus apex, synapomorphic for these taxa.Interfamilial homologies for most of the Simuliidae larval palpal sensilla are established for those of larvae of Thaumaleidae, Chironomidae, Tanyderidae, and Blephariceridae. Very few homologies could be established for the Culicidae. Thirteen or 14 palpal sensilla appear to be plesiomorphic for larval nematocerous Diptera, with Simuliidae and Culicidae having reduced numbers.