Japanese queens: identification key and species diagnoses (Hymenoptera, Formicidae, Myrmicinae).

In Japan, nine species have been known in the ant genus , of which five or more are considered tramps. A key to the queens of nine species found in Japan is presented. The tramp species Mayr, 1870 is excluded from the key because no queen was available for us, while Mayr, 1870 is included because it was once intercepted at a port in Japan and exotic queens were available. Diagnosis of the queen of each species is provided together with differences between the two female castes. Bolton, 1977 is resurrected from synonymy with Forel, 1905 based mainly on the queen characters.