LAUSR

Abstract Studies on the ultrastructural morphology of species by means of Scanning Electron Microscopy (SEM) provide information about their habits and biological adaptations to the environment. Flies of the Neotropical genus Neodexiopsis Malloch (Muscidae: Coenosiini) show notable adaptations related to the environment and feeding, at each of their life stages. Adults are predators of small insects and inhabit forests or pastures, while eggs are adapted to aquatic environments. This study focused on the species Neodexiopsis rufipes (Macquart, 1851). We present for the first time the ultrastructural morphology with SEM images of the egg, which shows a respiratory structure (a kind of plastron) adapted to lentic environments, as well as of the proboscis, which shows hook-like teeth adapted to capture the prey in flight and transport it to a place for feeding. Also, we present a complete morphological description of N. rufipes with detailed images of the terminalia, and propose a new synonymy: N. microchaeta as a new junior synonym of N. rufipes .