S. signatus species-group

Diagnosis. Eyes contiguous on frons, flattened dorsally so that the head appears flattened dorsally, with upper facets enlarged. Arista bare. Rs rather long; R4+5 and M1 usually convergent apically; anal cell nearly as long as basal cells. Hind leg distinctly elongated with swollen coxa. Hind femur with ventral tubercles usually finger-like, bearing strong bristles, shorter in females. Hind tibia in both sexes curved, apically thickened, and usually with weak ventral tubercles bearing weak bristles. Abdomen broad, flattened dorsoventrally.

Remarks. For detailed description of the characters, see Yang and Yang (2004).