Achnanthidium exiguum var. constrictum (Grunow) N.A.Andresen, E.F.Stoermer & R.G.Kreis, 2000 accepted as
Stauroneis exilis var. constricta Grunow, 1867 (new combination reference)
Achnanthidium semiaperta (Guermeur) Andresen Stoermer & Kreis (new combination reference)
Achnanthidium semiapertum (P. Guermeur) N.A. Andresen, E.F. Stoermer & R.G. Kreis, Jr., 2000 accepted as
Achnanthes exigua f. semiaperta Guermeur, 1954 (new combination reference)
Aneumastus tuscula f. minor N.A.Andresen, E.F.Stoermer & R.G.Kreis, Jr., 2000 (original description)
Aneumastus tuscula f. obtusus (Hustedt) N.A.Andresen, E.F.Stoermer & R.G.Kreis, Jr., 2000 accepted as
Navicula tuscula var. obtusa Hustedt, 1922 (new combination reference)
Aneumastus tuscula var. rostratus (Hustedt) N.A.Andresen, E.F.Stoermer & R.G.Kreis Jr., 2000 accepted as
Navicula tuscula var. rostrata Hustedt, 1911 (new combination reference)
Fragilariforma virescens var. mesolepta Rabenhorst (new combination reference)
Fragilariforma virescens var. oblongella (Grunow) E.Y.Haworth & M.G.Kelly accepted as
Fragilaria virescens f. oblongella Grunow in Van Heurck, 1881 (new combination reference)
Placoneis placentula var. rostrata (Mayer) N.A.Andresen, E.F.Stoermer & R.G.Kreis, Jr., 2000 (new combination reference)
Planothidium hauckianum var. rostratum (Schulz ex Hustedt) N.A.Andresen, E.F.Stoermer & R.G.Kreis, Jr., 2000 (new combination reference)
Planothidium lanceolatum var. bimaculatum (Hustedt) N.A. Andresen, E.F. Stoermer & R.G. Kreis, Jr., 2000 (new combination reference)
Planothidium lanceolatum var. genuinum N.A. Andresen, E.F. Stoermer & R.G. Kreis, Jr., 2000 (original description)
Planothidium lanceolatum var. omissum (C.W.Reimer) N.A.Andresen, E.F.Stoermer & R.G.Kreis, Jr, 2000 (new combination reference)
Planothidium peragalloi var. fossilum (Tempère & Peragallo) N.A. Andresen, E.F. Stoermer & R.G. Kreis, Jr., 2000 (new combination reference)
Planothidium peragalloi var. parvulum (R. Patrick) N.A. Andresen, E.F. Stoermer & R.G. Kreis, Jr., 2000 (new combination reference)
Pseudostaurosira brevistriata var. binodis (Pantocsek) N.A.Andresen, E.F.Stoermer & R.G.Kreis, Jr., 2000 (new combination reference)
Pseudostaurosira brevistriata var. capitata (Héribaud-Joseph) N.A.Andresen, E.F.Stoermer & R.G.Kreis, Jr., 2000 (new combination reference)
Sellaphora bacillarioides (Grunow) N.A. Andressen, E.F. Stoermer & R.G. Kreis, Jr., 2000 (new combination reference)
Sellaphora nyassensis f. minor (Otto Müller) N.A.Andresen, E.F.Stoermer & R.G.Kreis, Jr., 2000 (new combination reference)
Stauroneis construens var. capitata (Brun & Héribaud) N.A. Andresen, E.F. Stoermer & R.G. Kreis, Jr., 2000 (new combination reference)
Stauroneis exigua var. constricta Grunow in N.A. Andresen, E.F. Stoermer & R.G. Kreis, Jr., 2000 (original description)
Staurosira construens var. minuta (Tempère & Peragallo) N.A. Andresen, E.F. Stoermer & R.G. Kreis, Jr., 2000 (new combination reference)
Staurosira construens var. subsalina (Hustedt) N.A.Andresen, E.F.Stoermer & R.G.Kreiss, 2000 (new combination reference)
Staurosirella leptostauron var. fossilis (Pantocsek) N.A. Andresen, E.F. Stoermer & R.G. Kreis, Jr., 2000 (new combination reference)
Staurosirella leptostauron var. rhomboides (Grunow) Bukhtiyarova, 1995 accepted as
Fragilaria harrisonii var. rhomboides Grunow, 1862 (new combination reference)
Urosolenia gracilis (H.L.Smith) N.A.Andresen, E.F.Stoermer & R.G.Kreis, 2000 accepted as
Rhizosolenia gracilis H.L.Smith, 1882 (new combination reference)