Evolution of the Antenna in the Stratiomyidae (Diptera)

The evolution of the stratiomyid antenna follows 3 main lines represented by the Pachygastrinae, Sarginae, and Stratiomyinae-Clitellarinae complex. The major evolutionary trends are: (1) a gradual reduction from 8 to 5 flagellomeres, (2) a gradual reduction in the number of flagellomeres with sensory pits, (3) development of a style, (4) development of a terminal or dorsal arista, and (5) a gradual increase in the degree to which the flagellomeres are fused. The aristate antenna of the Sarginae and Pachygastrinae, which has the basal flagellomeres fused into homogeneous spherical mass, is more advanced and closely related to the aristate antenna of the Cyclorrhapha. The 8-segmented flagellum of the Cyphomyiinae is closely related to that of the Nematocera. Since various intermediate forms occur between these 2 types of antennae the Stratiomyidae are believed to represent the transitional stages between the antennal types of the Nematocera and Cyclorrhapha.