Characteristics
Sobarocephala affinis is characterized by a densely plumose arista, a dark dorsal stripe on the first flagellomere), well-developed ocellar bristles, and an almost entirely yellow body excluding part of the fore legs, the lateral margin of the scutum and the female abdomen.

Similar species
Sobarocephala muesebecki, the sister species of S. affinis, has much the same distribution but is known from further west into Pennsylvania and Texas. Males of these species are easy to distinguish because the epandrium is brown in S. muesebecki and yellow in S. affinis. Females are much more difficult to diagnose, particularly when poorly-preserved. The bristles of S. affinis are more yellow in colour and the anterior margin of the frons is never paler than the rest (sometimes light yellow to white in S. muesebecki). The wing of S. muesebecki is also lightly clouded apically (sometimes difficult to discern), and the hind tibia and tarsi are usually brownish.

Distribution
Sobarocephala affinis is found along the eastern and southeastern coastal regions of the United States from New England south to Alabama. Specimens have not been found in Maine or peninsular Florida.

Biology
Specimens have been collected using mushroom, pitfall, pan and Malaise traps, and have often been found at dung.