Myrmecium is a genus of ant-mimicking corinnid sac spiders first described by Pierre André Latreille in 1824. The unrelated jumping spider species Synemosyna formica has been mistaken for a member of this genus twice, once by Eugène Simon in 1897 (Myrmecium lunatum) and once by Cândido Firmino de Mello-Leitão in 1932 (Myrmecium rubrum).