Aneumastus stroesei (Østrup) D.G.Mann, 1990 accepted as Navicula tuscula var. stroesei Østrup, 1910 (new combination reference)
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)
Asterionellopsis kariana (Grunow) Round, 1990 accepted as Asterionella kariana Grunow, 1880 (new combination reference)
Biremis ambigua (Cleve) D.G.Mann, 1990 accepted as Pinnularia ambigua var. ambigua Cleve, 1895 (new combination reference)
Bleakeleya notata (Grunow) Round, 1990 accepted as Asterionella bleakeleyi var. notata Grunow, 1867 (new combination reference)
Cavinula cocconeiformis (Gregory ex Greville) D.G.Mann & A.J.Stickle, 1990 accepted as Navicula cocconeiformis f. cocconeiformis Gregory ex Greville, 1855 (new combination reference)
Cavinula lacustris (W.Gregory) D.G.Mann & Stickle, 1990 accepted as Navicula lacustris f. lacustris Gregory, 1856 (new combination reference)
Cavinula pseudoscutiformis (Hustedt) D.G.Mann & A.J.Stickle, 1990 accepted as Navicula pseudoscutiformis Hustedt, 1930 (new combination reference)
Cavinula variostriata (Krasske) D.G.Mann & A.J.Stickle, 1990 accepted as Navicula variostriata var. variostriata Krasske, 1923 (new combination reference)
Cosmioneis lundstroemii (Cleve) D.G.Mann, 1990 accepted as Navicula lundstroemii var. lundstroemii Cleve in Cleve & Grunow, 1880 (new combination reference)
Cosmioneis pusilla (W.Smith) D.G.Mann & A.J.Stickle, 1990 accepted as Navicula pusilla f. pusilla W. Smith, 1853 (new combination reference)
Craticula ambigua (Ehrenberg) D.G.Mann, 1990 accepted as Navicula ambigua f. ambigua Ehrenberg, 1843 (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)
Encyonema elginense (Krammer) D.G.Mann, 1990 (new combination reference)
Encyonema lacustre (C.Agardh) F.W.Mills, 1934 accepted as Schizonema lacustre C.Agardh, 1824 (new combination reference)
Encyonema minutum (Hilse) D.G.Mann, 1990 accepted as Cymbella minuta Hilse, 1862 (new combination reference)
Encyonema perpusillum (Cleve) D.G.Mann, 1990 accepted as Cymbella perpusilla A.Cleve, 1895 (new combination reference)
Encyonema silesiacum (Bleisch) D.G.Mann, 1990 accepted as Cymbella silesiaca Bleisch, 1864 (new combination reference)
Fallacia cryptolyra (Brockmann) Stickle & Mann, 1990 accepted as Navicula cryptolyra Brockmann, 1950 (new combination reference)
Fallacia forcipata (Greville) Stickle & Mann, 1990 accepted as Navicula forcipata f. forcipata Greville, 1859 (new combination reference)
Fallacia pygmaea (Kützing) A.J.Stickle & D.G.Mann, 1990 (new combination reference)
Fallacia subhamulata (Grunow) D.G.Mann, 1990 accepted as Navicula subhamulata var. subhamulata Grunow in Van Heurck, 1880 (new combination reference)
Luticola D.G. Mann in F.E. Round, R.M. Crawford & D.G. Mann, 1990 (original description)
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 abrupta (Gregory) D.G.Mann, 1990 accepted as Navicula lyra var. abrupta Gregory, 1857 (new combination reference)
Lyrella hennedyi (W.Smith) Stickle & D.G.Mann, 1990 accepted as Navicula hennedyii f. hennedyii W. Smith, 1856 (new combination reference)
Martyana martyi (Héribaud-Joseph) Round, 1990 accepted as Opephora martyi f. martyi Héribaud, 1902 (new combination reference)
Oxyneis binalis (Ehrenberg) Round, 1990 (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 granulata (Bailey) D.G.Mann, 1990 accepted as Navicula granulata Bailey, 1854 (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)
Proschkinia longirostris (Hustedt) D.G.Mann, 1990 accepted as Navicula longirostris var. longirostris Hustedt, 1925 (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)
Seminavis D.G. Mann in F.E. Round, R.M. Crawford & D.G. Mann, 1990 (original description)
Staurophora amphioxys (Gregory) D.G.Mann, 1990 accepted as Stauroneis amphioxys var. amphioxys Gregory, 1856 (new combination reference)
Staurophora elata (Hustedt ex Simonsen) D.G.Mann, 1990 accepted as Stauroneis elata Hustedt, 1987 (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 hungarica (Grunow) Frenguelli, 1942 accepted as Nitzschia hungarica f. hungarica Grunow, 1862 (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)
Urosolenia eriensis (H.L.Smith) Round & R.M.Crawford, 1990 accepted as Rhizosolenia eriensis f. eriensis H.L. Smith, 1872 (new combination reference)