Scellus

Scellus is a genus of flies in the family Dolichopodidae. It is distributed in the Palearctic and Nearctic. Males of the genus have a pair of flag-like appendages, known as "signa" (singular "signum"), that emanate laterally from between the 4th and 5th abdominal segments. These appendages are connected together by a band under the sternites, forming a U-shaped structure called the "cingulum". It has been suggested by researchers that these appendages are used for visual signalling or pheromone dispersal during courtship. The genus Hydatostega also has a cingulum, but much reduced, suggesting that Scellus and Hydatostega are closely related.