Platycheirus (Carposcalis) stegnus (Say)
Platycheirus (Carposcalis) stegnus (Say, 1829).
Say, T. (1829-30) Descriptions of North American dipterous insects. Journal of the Academy of Natural Sciences of Philadelphia (1829) 6, 149-178 [1829.07.??], 183-188. [1830.08.??].