Placoneis amphibola (Cleve) E.J.Cox, 2003 accepted as Navicula amphibola f. amphibola Cleve, 1891 (new combination reference)
Placoneis anglica (Ralfs) R.Lowe, 2004 accepted as Navicula anglica f. anglica Ralfs in Pritchard, 1861 (new combination reference)
Placoneis constans (Hustedt) E.J. Cox, 2003 accepted as Navicula constans var. constans Hustedt, 1944 (new combination reference)
Placoneis insignita (Hustedt) E.J.Cox, 2003 accepted as Navicula insignita f. insignita Hustedt, 1942 (new combination reference)
Placoneis interglacialis (Hustedt) E.J. Cox, 2003 accepted as Navicula interglacialis Hustedt, 1944 (new combination reference)
Placoneis navicularis (Ehrenberg) E.J.Cox, 2003 accepted as Amphiprora navicularis Ehrenberg, 1843 (new combination reference)
Placoneis porifera (Hustedt) T.Ohtsuka & Y.Fujita (new combination reference)
Placoneis rostrata (A.Mayer) E.J.Cox, 2003 accepted as Navicula dicephala var. rostrata A.Mayer, 1917 (new combination reference)
Placoneis subgastriformis (Hustedt) E.J. Cox, 2003 accepted as Navicula subgastriformis Hustedt, 1945 (new combination reference)
Placoneis subplacentula (Hustedt) E.J. Cox, 2003 accepted as Navicula subplacentula var. subplacentula Hustedt in Schmidt et al., 1930 (new combination reference)