Olfactory sensilla on antennae and maxillary palps of Fannia hirticeps (Stein, 1892) (Diptera: Fanniidae).

The Fanniidae is one of four families in the superfamily Muscoidea (Diptera), including some important medical and hygienic flies. There is a paucity of reports on the ultrastructure of olfactory sensilla for the fanniid species. To provide more information on the morphology of the antennal and palpal sensilla of fanniid fly, Fannia hirticeps (Stein, 1892) has been studied using scanning electron microscopy. The first two antennal segments, scape and pedicel, are covered by microtrichiae and several chaetic sensilla. Six distinct morphological types of sensilla are recorded on the antennal funiculus, including one trichoid, two basiconic, two coeloconic sensilla, and one clavate sensilla. The measurement and density of each sensilla type are also provided. The trichoid sensilla tend to be longer and denser toward the apex of antennal funiculus. Basiconic sensilla spread all over the funicular surface. F. hirticeps bears two types of coeloconic sensilla, type 2 coeloconic sensilla distributed on the distal part of the anterior surface, whereas type 1 distributed on the rest of the funiculus. Clavate sensilla are found on the base of antennal funiculus. Only one large sensory pit is located on the posterior surface. Maxillary palps bear one type of basiconic sensilla. These results are compared with eight other muscid flies. Our findings provide a morphological basis for future investigations on olfactory-mediated behavior of this group.