Abstract. Morphological evidence from the adults males, females corroborates the recent transfer of the problematic New World genusCoenosopsiafrom the Muscidae to the Anthomyiidae. It is argued that the calyptrate families Anthomyiidae and Muscidae are sister­groups, and that a Neotropical anthomyiid clade,CoenosopsiaMalloch +PhaonanthoAlbuquerque, constitutes the sister‐group of the remaining Anthomyiidae. At present, this clade is largely confined to tropical forests of South and Central America, i.e. an environment avoided by practically all other members of this pronouncedly cold‐adapted, boreal family. The first, earliest Coenozoic, biotic exchange between North and South America and subsequent biotic isolation are proposed to lie behind the primary dichotomy of the Anthomyiidae. Five species ofCoenosopsia, with apparently perfectly allopatric ranges, are recog nized: the NeotropicalC.primaMalloch from Ecuador to SE Mexico,C.peruvianasp.n. from Peru,C.brasiliensissp.n. from Brazil, andC.mexicanasp.n. from SW Mexico, and the NearcticC.floridensissp.n. from N Mexico and SE United St