Diploneis aestiva var. fusca (Gregory) R. Ross 1986
Homotypic synonym according to GBIF classification (Originally found in sources as synonym of Navicula smithii var. fusca Gregory, 1857)
Diploneis chersonensis (Grunow) Cleve 1894
Doubtful according to GBIF classification (Possible variant of Diploneis chersonensis Grove)
Diploneis coffaeiformis var. densestriata (Schmidt) Cleve 1894
Homotypic synonym according to GBIF classification (Originally found in sources as accepted taxon within Diploneis coffaeiformis (Schmidt) Cleve, 1894)
Diploneis didyma (Ehrenb.) Cleve
Doubtful according to GBIF classification (Possible variant of Diploneis didyma F.W.Mills)
Diploneis finnica var. clevei (Fontell) Hustedt 1937