Amphipleura pellucida f. minor Dippel, 1905 (original description)
Cymatopleura elliptica f. minor Dippel, 1905 (original description)
Cymbella gastroides var. truncata (Rabenhorst) Dippel, 1905 accepted as Cymbella truncata Rabenhorst, 1853 (new combination reference)
Cymbella ventricosa var. caespitosa (Kützing) Dippel, 1905 accepted as Encyonema caespitosum Kützing, 1849 (new combination reference)
Eunotia arcus f. curta (Grunow) Dippel, 1905 accepted as Eunotia arcus var. curtum Grunow, 1862 (new combination reference)
Eunotia gracilis f. minor Dippel, 1905 (original description)
Gomphonema acuminatum f. intermedia Dippel, 1905 (original description)
Gomphonema acuminatum f. laticeps (Ehrenberg) L.Dippel, 1905 accepted as Gomphonema laticeps Ehrenberg, 1843 (new combination reference)
Hantzschia amphioxys f. pusilla (Grunow) Dippel, 1905 accepted as Nitzschia pusilla Grunow, 1862 (new combination reference)
Melosira crenulata f. tenuis (Kützing) Van Heurck, 1885 accepted as Melosira tenuis var. tenuis Kützing, 1844 (new combination reference)
Navicula affinis var. intermedia Dippel, 1905 (original description)
Navicula cuspidata f. capitata Dippel, 1905 (original description)
Navicula fulva f. asymmetrica Dippel, 1905 (original description)
Navicula iridis f. minor Dippel, 1905 (original description)
Navicula oblonga var. lanceolata sensu Dippel, 1905 (original description)
Navicula ovalis var. oblongella (Nägeli) Dippel, 1905 accepted as Navicula oblongella var. oblongella Naegeli in Kutzing, 1849 (new combination reference)
Navicula producta sensu Dippel, 1905 (original description)
Navicula reinhardtii var. ovalis Dippel, 1905 (original description)
Navicula sphaerophora var. sculpta (Ehrenberg) Dippel, 1905 accepted as Navicula sculpta var. sculpta Ehrenberg, 1854 (new combination reference)
Nitzschia angustata f. acuta sensu Dippel, 1905 (original description)
Nitzschia angustata f. curta Dippel, 1905 (original description)
Nitzschia tryblionella f. curta Dippel, 1905 (original description)
Nitzschia vitrea var. arcuata Dippel, 1905 (original description)
Pinnularia bicapitata (N.G.W.Lagerstedt) L.Dippel, 1905 accepted as Navicula bicapitata f. bicapitata Lagerstedt, 1873 (new combination reference)
Pinnularia bicapitata var. interrupta (W.Smith) L.Dippel, 1905 accepted as Pinnularia interrupta f. interrupta W. Smith, 1853 (new combination reference)
Pinnularia major Dippel, 1905 (original description)
Pinnularia major f. linearis (Cleve) Dippel, 1905 (new combination reference)
Pinnularia nobilis f. intermedia Dippel, 1905 (original description)
Pleurosigma acuminatum f. obtusa Dippel, 1905 (original description)
Pleurosigma acuminatum var. obtusa Dippel, 1905 (original description)
Stauroneis phoenicenteron f. brevis (Dippel) Hustedt, 1930 (original description)
Stauroneis phoenicenteron f. gracilis (Dippel) Hustedt, 1930 (original description)
Stauroneis phoenicenteron f. intermedia Dippel, 1905 (original description)
Stauroneis phoenicenteron f. truncata Dippel, 1905 (original description)
Stauroneis phoenicenteron f. vulgaris Dippel, 1905 (original description)
Surirella biseriata f. media Dippel, 1905 (original description)
Surirella biseriata f. minor Dippel, 1905 (original description)
Surirella ovalis f. aequalis Dippel, 1905 (original description)
Surirella ovalis f. subovata Dippel, 1905 (original description)
Surirella robusta f. minor Dippel, 1905 (original description)