Lygaeus quadratus Fabricius, 1798: 541. NT (Scudder & Wagner, 1964: 359): male, Germany, Hannover, Neu-Darchau; MNHN.
Aphanus quadratus var. immaculatus Royer, 1919: 39 (upgraded to species by Stichel, 1959b: 274; syn. Péricart, 1999c: 280). HT: France, nr Fontainebleau, Veneux-Nadon; MNHN?
Aphanus brevirostris Ribaut, 1921a: 68 (syn. Royer, 1923a: 250, with immaculatus). LT (Péricart, 1998a: 277): male, France, Haute-Garonne, Saint-Béat; MNHN.
Rhyparochromus (Neoxanthochilus) quadratus interruptus Wagner, 1956r: 281 (syn. Péricart, 1999c: 280). HT: France, forêt de Fontainebleau; ZMUH.