A singular group of 19 species of Neotropical Trichomyia Haliday in Curtis, 1839 presents four segments in the palpus, the first two partially fused; five of these species were included in the subgenus Opisthotrichomyia Bravo, 2001 and seven in the subgenus BrachiotrichomyiaBravo & Araújo, 2013. A new species from Brazil is described and a new subgenus proposed for four Neotropical species of this morphological group: T. biloba Quate, 1999 from Panama, and T. onorei Bravo, 2002, T. queirozi Bravo, 2002 and T. horrida sp. nov. from Brazil. Syntrichomyia subgen. nov. can be recognized by its fused gonocoxites and gonostyli, and by its bilobed hypoproct. A key to the known species (males) of this new subgenus is presented.
Brazil; Neotropics; Syntrichomyia subgen. nov; taxonomy; Trichomyiinae