• Cylindrotheca closterium (Ehrenberg) Reimann & J.C.Lewin, 1964
• Cylindrotheca gracilis (Brébisson ex Kützing) Grunow, 1882 (uncertain > unassessed)
• Fragilariopsis barbieri (M. Peragallo) Cefarelli, Ferrario & Lundholm, 2021
• Fragilariopsis curta (Van Heurck) Hustedt, 1958
• Fragilariopsis cylindrus (Grunow) Krieger, 1954 (uncertain > unassessed)
• Fragilariopsis kerguelensis (O'Meara) Hustedt, 1952 accepted as Terebraria kerguelensis E.O'Meara, 1876 †
• Fragilariopsis linearis (Castracane) Frenguelli, 1943 accepted as Fragilaria linearis f. linearis Castracane, 1886
• Fragilariopsis obliquecostata (van Heurck) Heiden, 1928
• Fragilariopsis pseudonana (Hasle) Hasle, 1993 (uncertain > unassessed)
• Fragilariopsis rhombica (O'Meara) Hustedt, 1952 accepted as Diatoma rhombica E.O'Meara, 1877
• Fragilariopsis ritscheri Hustedt, 1958 (uncertain > unassessed)
• Fragilariopsis separanda Hustedt, 1958 (uncertain > unassessed)
• Fragilariopsis sublinearis (Van Heurck) Heiden & Kolbe, 1943 accepted as Fragilariopsis obliquecostata (van Heurck) Heiden, 1928
• Fragilariopsis vanheurckii (Peragallo) Hustedt, 1958 accepted as Fragilaria vanheurckii Peragallo, 1921
• Nitzschia acicularis (Kützing) W.Smith, 1853 (uncertain > unassessed)
• Nitzschia australis (Peragallo) A.Mann, 1937 accepted as Nitzschia dubia var. australis Peragallo, 1921
• Nitzschia barbieri M. Peragallo, 1921 accepted as Fragilariopsis barbieri (M. Peragallo) Cefarelli, Ferrario & Lundholm, 2021
• Nitzschia bicapitata Cleve, 1901 (uncertain > unassessed)
• Nitzschia compacta Hustedt, 1958 (uncertain > unassessed)
• Nitzschia decipiens Hustedt, 1958 (uncertain > unassessed)
• Nitzschia dubia W.Smith, 1853
• Nitzschia dubia var. australis Peragallo, 1921 (uncertain > unassessed)
• Nitzschia lecointei van Heurck, 1909 (uncertain > unassessed)
• Nitzschia lineola Cleve, 1897 (uncertain > unassessed)
• Nitzschia longissima (Brébisson) Ralfs, 1861
• Nitzschia medioconstricta Hustedt, 1958 (uncertain > unassessed)
• Nitzschia peragallii Hasle, 1965
• Nitzschia sicula (Castracane) Hustedt
• Nitzschia sicula var. bicuneata (Grunow) Hasle, 1960 accepted as Rhaphoneis bicuneata Grunow in Cleve & Möller, 1879
• Nitzschia stellata Manguin, 1957 (uncertain > unassessed)
• Nitzschia subcurvata G.R.Hasle, 1964 (uncertain > unassessed)
• Nitzschia taenia W.Smith, 1853 (uncertain > unassessed)
• Nitzschia turgidula Hustedt, 1958 (uncertain > unassessed)
• Pseudonitzschia antarctica Manguin, 1960 (uncertain > unassessed)
• Pseudo-nitzschia antarctica Manguin, 1960
• Pseudonitzschia heimii Manguin, 1960 (uncertain > unassessed)
• Pseudo-nitzschia heimii Manguin, 1957
• Pseudonitzschia lineola (P. T. Cleve) Hasle, 1993 accepted as Nitzschia lineola Cleve, 1897
• Pseudo-nitzschia lineola (Cleve) Hasle, 1965
• Pseudonitzschia prolongatoides (Hasle) Hasle, 1993 (uncertain > unassessed)
• Pseudo-nitzschia prolongatoides (G.R.Hasle) G.R.Hasle, 1993
• Pseudonitzschia subcurvata (Hasle) Fryxell in Hasle, 1993 accepted as Nitzschia subcurvata G.R.Hasle, 1964
• Pseudo-nitzschia subcurvata (G.R.Hasle) G.A.Fryxell, 1993
• Pseudonitzschia turgidula (Hustedt) Hasle, 1993 accepted as Nitzschia turgidula Hustedt, 1958
• Pseudo-nitzschia turgidula (Hustedt) G.R.Hasle, 1993
• Pseudonitzschia turgiduloides Hasle, 1995 (uncertain > unassessed)
• Pseudo-nitzschia turgiduloides (G.R.Hasle) G.R.Hasle, 1996
• Tryblionella compressa (J.W.Bailey) M.Poulin, 1990 accepted as Pyxidicula compressa var. compressa J.W. Bailey, 1851