In this study we synonymise the genus Decamorium Forel under Tetramorium Mayr, revise the new T.decem species group by providing a diagnosis of the group, an tuffer bags illustrated identification key to species level, and worker-based species descriptions for all five species, which include diagnoses, discussions, images, mabis dmi healthcare and distribution maps.The following species are revised in this study: T.decem Forel, comb.r.
, T.raptor sp.n., T.uelense Santschi, comb.
r., T.ultor Forel, comb.r., stat.
r.& stat.n., and T.venator sp.
n.In addition, we also designate lectotypes for T.decem, T.uelense, and T.ultor.