Comparative morphology of antennal ultrastructure in Tachinidae parasitoid flies (Diptera): The phylogenetic importance of antennal sensilla

Tachinidae are one of the most diverse clades of Diptera. All tachinids are parasitoids of insects and other arthropods, and thus are considered an important source of biological pest control. Antennae are the most important olfactory organs of Tachinidae playing key roles in their lives, especially in locating hosts, and details of antennal ultrastructure could provide useful features for phylogenetic studies and understanding their adaptive evolution. Despite the ecological and evolutionary importance of antennae, the current knowledge of antennal ultrastructure is scarce for Tachinidae. Our study examined antennal sensilla of thirteen species belonging to thirteen genera within eleven tribes of all the four subfamilies (Phasiinae, Dexiinae, Tachininae, and Exoristinae): Beskia aelops Walker, Trichodura sp., Voria ruralis (Fallén), Zelia sp., Cylindromyia carinata Townsend, Phasia xenos Townsend, Neomintho sp., Genea australis (Townsend), Copecrypta sp., Hystricia sp., Belvosia sp., Leschenaultia sp., and Winthemia pinguis (Fabricius). Types, length and distribution of antennal sensilla were investigated via scanning electron microscopy (SEM). Our comparative analysis summarized 29 variable characters and we evaluated their phylogenetic signal for subfamilial, tribal and generic/specific levels, showing that antennal ultrastructure could be a reliable source of characters for phylogenetic analysis. Our findings demonstrate the remarkable diversity of the antennal ultrastructure of Tachinidae.