Scanning electron microscopy in two species of Fannia Robineau-Desvoidy, (Diptera, Fanniidae). The species Fannia pusio Wiedemann, 1830 and F. trimaculata Stein, 1898 belong to the canicularis group and pusio subgroup. These species are morphologically very similar and usually distinguished from each other by a line of bristles on the males hind femur. The scanning electron microscopy analysis showed a smaller number of orifices on the dorsal surface of the egg in the structure called "cellas" and, on the ventral surface, less rugosity was noted, both in F. trimaculata. On the larvae, the stigma or protothoracic spiracle was outstanding, where F. trimaculata possess two short tegumental extensions and seven long ones, while F. pusio has nine extensions, all long, of equal length. Males of F. trimaculata present alongside a line of longer bristles located more externally on the facet, another line of shorter bristles, which is absent in males of F. pusio, but present in females of both species.
Differences; Fannia pusio; Fannia trimaculata; morphology; SEM
