Aneumastus tuscula (Ehrenberg) D.G.Mann & A.J.Stickle, 1990 † accepted as Navicula tuscula f. tuscula Ehrenberg, 1840 (new combination reference)
Asterionellopsis glacialis (Castracane) Round, 1990 accepted as Asterionella glacialis Castracane, 1886 (new combination reference)
Biremis ambigua (Cleve) D.G.Mann, 1990 accepted as Pinnularia ambigua var. ambigua Cleve, 1895 (new combination reference)
Cavinula lacustris (W.Gregory) D.G.Mann & Stickle, 1990 accepted as Navicula lacustris f. lacustris Gregory, 1856 (new combination reference)
Cavinula scutiformis (Grunow ex A.Schmidt) D.G.Mann & A.J.Stickle, 1990 accepted as Navicula scutiformis f. scutiformis Grunow in Schmidt et al., 1881 (new combination reference)
Craticula cuspidata (Kutzing) D.G.Mann, 1990 accepted as Frustulia cuspidata Kutzing, 1833 (new combination reference)
Craticula halophila (Grunow) D.G.Mann, 1990 accepted as Navicula cuspidata var. halophila Grunow, 1885 (new combination reference)
Fallacia forcipata (Greville) Stickle & Mann, 1990 accepted as Navicula forcipata f. forcipata Greville, 1859 (new combination reference)
Fallacia fracta (Hustedt ex Simonsen) D.G.Mann, 1990 accepted as Navicula fracta Hustedt, 1987 (new combination reference)
Fallacia pygmaea (Kützing) A.J.Stickle & D.G.Mann, 1990 (new combination reference)
Luticola D.G. Mann in F.E. Round, R.M. Crawford & D.G. Mann, 1990 (original description)
Luticola inserata (Hustedt) D.G.Mann, 1990 accepted as Navicula inserata var. inserata Hustedt, 1955 (new combination reference)
Luticola mutica (Kützing) D.G.Mann, 1990 accepted as Navicula mutica f. mutica Kützing, 1844 (new combination reference)
Luticola nivalis (Ehrenberg) D.G.Mann, 1990 accepted as Navicula nivalis var. nivalis Ehrenberg, 1853 (new combination reference)
Lyrella approximata (Greville) D.G.Mann, 1990 accepted as Navicula approximata f. approximata Greville, 1859 (new combination reference)
Lyrella clavata (Gregory) D.G.Mann, 1990 (new combination reference)
Lyrella hennedyi (W.Smith) Stickle & D.G.Mann, 1990 accepted as Navicula hennedyii f. hennedyii W. Smith, 1856 (new combination reference)
Lyrella inhalata (A.Schmidt) D.G.Mann, 1990 accepted as Navicula inhalata var. inhalata Schmidt in Schmidt et al., 1874 (new combination reference)
Lyrella lyroides (Hendey) D.G.Mann, 1990 accepted as Navicula lyroides f. lyroides Hendey, 1958 (new combination reference)
Lyrella nebulosa (Gregory) D.G.Mann, 1990 accepted as Navicula nebulosa Gregory, 1857 (new combination reference)
Lyrella praetexta (Ehrenberg) D.G.Mann, 1990 accepted as Navicula praetexta f. praetexta Ehrenberg, 1840 (new combination reference)
Lyrella spectabilis (Gregory) D.G.Mann, 1990 accepted as Navicula spectabilis f. spectabilis Gregory, 1857 (new combination reference)
Martyana martyi (Héribaud-Joseph) Round, 1990 accepted as Opephora martyi f. martyi Héribaud, 1902 (new combination reference)
Microtabella interrupta (Ehrenberg) Round, 1990 accepted as Tessella interrupta Ehrenberg, 1838 (new combination reference)
Petrodictyon D.G. Mann in F.E. Round, R.M. Crawford & D.G. Mann, 1990 (original description)
Petrodictyon gemma (Ehrenberg) D.G.Mann, 1990 accepted as Surirella gemma f. gemma Ehrenberg, 1840 (new combination reference)
Petroneis arabica (Grunow ex Schmidt) D.G.Mann, 1990 accepted as Navicula arabica var. arabica Grunow in Schmidt et al., 1875 (new combination reference)
Petroneis humerosa (Brébisson ex W.Smith) A.J.Stickle & D.G.Mann, 1990 accepted as Navicula humerosa f. humerosa Brébisson ex W. Smith, 1856 (new combination reference)
Petroneis latissima (Gregory) A.J.Stickle & D.G.Mann, 1990 accepted as Navicula latissima f. latissima Gregory, 1856 (new combination reference)
Petroneis marina (Ralfs) D.G.Mann, 1990 accepted as Navicula marina var. marina Ralfs in Pritchard, 1861 (new combination reference)
Petroneis monilifera (Cleve) A.J.Stickle & D.G.Mann, 1990 accepted as Navicula monilifera f. monilifera Cleve, 1895 (new combination reference)
Petroneis transfuga (Grunow ex Cleve) D.G.Mann, 1990 accepted as Navicula transfuga f. transfuga Grunow in Cleve, 1883 (new combination reference)
Psammodictyon D.G. Mann in F.E. Round, R.M. Crawford & D.G. Mann, 1990 (original description)
Psammodictyon constrictum (Gregory) D.G.Mann, 1990 accepted as Tryblionella constricta Gregory, 1855 (new combination reference)
Psammodictyon panduriforme (W.Gregory) D.G.Mann, 1990 accepted as Nitzschia panduriformis f. panduriformis Gregory, 1857 (new combination reference)
Scolioneis D.G. Mann in F.E. Round, R.M. Crawford & D.G. Mann, 1990 accepted as Navicula J.B.M. Bory de Saint-Vincent, 1822 (original description)
Scolioneis tumida (Brébisson ex Kützing) D.G.Mann, 1990 accepted as Navicula tumida var. tumida Brébisson in Kützing, 1849 (new combination reference)
Seminavis D.G. Mann in F.E. Round, R.M. Crawford & D.G. Mann, 1990 (original description)
Seminavis cymbelloides (Grunow) D.G.Mann, 1990 accepted as Amphora cymbelloides var. cymbelloides Grunow, 1867 (new combination reference)
Tryblionella coarctata (Grunow) D.G.Mann, 1990 accepted as Nitzschia coarctata var. coarctata Grunow in Cleve & Möller, 1878 (new combination reference)
Tryblionella cocconeiformis (Grunow) D.G.Mann in F.E.Round, R.A.Crawford & D.G.Mann, 1990 (new combination reference)
Tryblionella granulata (Grunow) D.G.Mann, 1990 accepted as Nitzschia granulata f. granulata Grunow in Cleve & Möller, 1879 (new combination reference)
Tryblionella hungarica (Grunow) Frenguelli, 1942 accepted as Nitzschia hungarica f. hungarica Grunow, 1862 (new combination reference)
Tryblionella jelineckii (Grunow) D.G.Mann, 1990 accepted as Nitzschia jelineckii var. jelineckii Grunow, 1863 (new combination reference)
Tryblionella littoralis (Grunow) D.G.Mann, 1990 accepted as Nitzschia littoralis var. littoralis Grunow in Cleve & Grunow, 1880 (new combination reference)
Tryblionella marginulata (Grunow) D.G.Mann, 1990 accepted as Nitzschia marginulata f. marginulata Grunow in Cleve & Möller, 1878 (new combination reference)