Mayr, 1863a: 457; Emery & Forel, 1879: 457 (Europe); Dalla Torre, 1893: 63; Emery, 1924f: 265; Smith, 1951c: 822 (North America); Smith, 1979: 1398 (North America); Bolton, 1995b: 211.
Mayr, 1865: 23 (diagnosis); André, 1882d: 279 (Europe & Algeria species); Emery, 1924f: 265 (diagnosis); Creighton, 1950a: 284 (Nearctic species key); Bernard, 1967a: 223 (diagnosis); Radchenko, 1994b: 112 (South Siberia species key); Bolton, 1995a: 1049 (census); Xu, 2012a: 21 (all species key); Cantone, 2017: 202 (brief male diagnosis).
Extant: 3 valid species, 1 valid subspecies (1 synonym)