H.W.C. Couzijn (1978, 1981) subdivided the genus into several subgenera, but F. Kovařík (2004) synonymized these subgenera with the nominal genus.
H.W.C. Couzijn (1978, 1981) a subdivizat genul în câteva subgenuri, dar F. Kovařík (2004) a sinonimizat aceste subgenuri cu genul nominal.