Sylvenomyia fennica sp. n., the second species of the genus Sylvenomyia Mamaev & Zaitzev is described from Finland. Sylvenomyia sueciae Mamaev & Zaitzev, the type species, is a new junior synonym of Chastomera spinigera Spungis. Sylvenomyia spinigera (Spungis) comb. n. is redescribed. The generic concept and systematic position of Sylvenomyia is reviewed. The genus Sylvenomyia is transferred from the tribe Winnertziini to the “Porricondylinae” incertae sedis.