NOTE: Krammer (1992) proposed taxonomic changes for several European taxa in the genus Pinnularia. These changes make the status of many taxa reported from the United States uncertain. Incorporating these changes here at this time would add to the confusion this list attempts to clarify, so the changes proposed by Krammer (1992) have not been noted. The reader should consult Krammer’s publication. Also, Round et al. (1990) suggested that the genera Pinnularia and Caloneis cannot stand as we now know them. More taxonomic changes are likely.

Pinnularia abaujensis (Pant.) Ross
    OK: Pfiester et al. (1979), Troeger (1983)
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula acrospheria (Bréb.) Kütz.
Pinnularia abaujensis var. linearis (Hust.) Patr.
    NE: Patrick & Reimer (1966)
        Synonyms:
            Navicula rangoonensis (Grun.) Elm.
Pinnularia abaujensis var. rostrata (Patr.) Patr.
    OK: Pfiester et al. (1979)
Pinnularia abaujensis var. subundulata (A. Mayer ex Hust.) Patr.
    OK: Troeger (1983)
        Synonyms:
            Pinnularia gibba f. subundulata A. Mayer
Pinnularia acrosphaeria W. Sm.
    KS: Wujek et al. (1980)
    MO: Pamperl (1980)
    OK: Pfiester et al. (1979), Troeger (1983)
    Plains States: Patrick & Reimer (1966)
Pinnularia acuminata W. Sm.
    KS: ?Patrick & Reimer (1966)
    OK: Pfiester et al. (1979)
        Synonyms:
            Navicula hemiptera Kütz.
Pinnularia aestuarii Cl.
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula stauroneiformis Elm.
Pinnularia amphioxys Ehr. = ?
    NE: Ehrenberg (1856)
    OK: Ehrenberg (1856)
Pinnularia appendiculata (Ag.) Cl.
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula appendiculata (Ag.) Kütz.
            Navicula obtusa Ehr.
Pinnularia biceps Greg.
    KS: Wujek et al. (1980)
    OK: Pfiester et al. (1979), Troeger (1978, 1983)
        Synonyms:
            Navicula interrupta (W. Sm.) A.S.
Pinnularia biceps f. petersenii Ross
    OK: Pfiester et al. (1979)
Pinnularia borealis Ehr.
    OK: Ehrenberg (1856), Pfiester & Terry (1978), Pfiester et al. (1979), Troeger (1978, 1983)
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula borealis (Ehr.) Kütz.
Pinnularia boyeri Patr.
    Plains States: Patrick & Reimer (1966)
Pinnularia braunii (Grun.) Cl.
    KS: Powers (1969)
    NE: Patrick & Reimer (1966)
    OK: Seyfer & Wilhm (1977), Wilhm et al. (1978)
        Synonyms:
            Navicula braunii Grun.
Pinnularia braunii var. amphicephala (A. Mayer) Hust.
    KS: Wujek et al. (1980)
    OK: Troeger (1978, 1983)
Pinnularia brebissonii (Kütz.) Rab.
    KS: Harris & Eberle (2001)
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula brebissonii Kütz.
            Pinnularia microstauron var. brebissonii (Kütz.) Hust.
Pinnularia brebissonii var. diminuta (Grun.) Cl.
    KS: Harris & Eberle (2001)
Pinnularia brevicostata Cl.
    OK: Troeger (1983)
Pinnularia capitata Ehr. = Navicula capitata Ehr.
    OK: Ehrenberg (1856)
Pinnularia conspicua (A.S.) Cl.
        Synonyms:
            Navicula conspicua A.S.
Pinnularia decurrens Ehr.
    NE: Ehrenberg (1856)
        Synonyms:
            Navicula decurrens (Ehr.) Kütz.
Pinnularia divergens W. Sm.
    Plains States: Patrick & Reimer (1966)
Pinnularia formica (Ehr.) Patr.
    OK: Pfiester et al. (1979)
Pinnularia gibba f. subundulata A. Mayer = Pinnularia abaujensis var. subundulata 
    (A. Mayer ex Hust.) Patr.
    OK: Pfiester & Terry (1978)
Pinnularia gibba var. mesogongyla (Ehr.) Hust. = Pinnularia mesogongyla Ehr.
    OK: Pfiester et al. (1979), Troeger (1978)
Pinnularia hilseana Jan. = Pinnularia subcapitata Greg. [see Patrick & Reimer 1966:595-596]
    NE: ?Patrick & Reimer (1966)
    OK: Pfiester et al. (1979)
Pinnularia inaequalis Ehr. = Cymbella inaequalis (Ehr.) Rab.
    NE: Ehrenberg (1856)
    OK: Ehrenberg (1856)
Pinnularia isostauron (Ehr.) Cl.
        Synonyms:
            Stauroptera isostauron Ehr.
Pinnularia lata (Bréb.) Rab.
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula lata (Bréb.) Kütz.
Pinnularia latevittata var. domingensis Cl.
    OK: Troeger (1978)
Pinnularia legumen (Ehr.) Ehr.
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula legumen Ehr.
Pinnularia macilenta (Ehr.) Ehr.
    OK: Ehrenberg (1856)
Pinnularia maior (Kütz.) Rab. [also as P. major]
    KS: Wujek (1965)
    OK: Pfiester et al. (1979)
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula major (Kütz.) Kütz.
            Pinnularia major (Kütz.) Rab.
Pinnularia maior var. transversa (A.S.) Cl.
    OK: Troeger (1978)
Pinnularia mesogongyla Ehr.
    OK: Pfiester et al. (1979)
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Pinnularia gibba var. mesogongyla (Ehr.) Hust.
Pinnularia mesolepta (Ehr.) W. Sm.
    OK: Troeger (1978)
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula mesolepta Ehr.
Pinnularia mesostyla (Ehr.) W. Sm.
        Synonyms:
            Navicula mesostyla Ehr.
Pinnularia microstauron (Ehr.) Cl.
    KS: Powers (1969)
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula bicapitata var. hybrida Grun.
            Navicula divergens f. minor A.S.
            Stauroptera microstauron Ehr.
Pinnularia microstauron f. biundulata (O. Müll.) Hust.
    OK: Pfiester & Terry (1978)
Pinnularia microstauron var. brebissonii (Kütz.) Hust. = Pinnularia brebissonii (Kütz.) Rab.
    OK: Pfiester & Terry (1978)
Pinnularia molaris (Grun.) Cl.
    OK: Pfiester & Terry (1978)
        Synonyms:
            Navicula macra Grun.
Pinnularia mormonorum (Grun.) Patr.
    OK: Pfiester et al. (1979)
Pinnularia nobilis (Ehr.) Ehr.
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula nobilis Ehr.
Pinnularia nodosa (Ehr.) W. Sm.
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula nodosa Ehr.
Pinnularia obscura Krasske
    OK: Pfiester et al. (1979), Troeger (1978, 1983)
    Plains States: Patrick & Reimer (1966)
Pinnularia parvula (Ralfs) Cl.-Euler
        Synonyms:
            Navicula gibba var. brevistriata V.H.
            Navicula stauroparva Grun.
            Navicula stauroptera var. parva Grun.
Pinnularia peregrina Ehr. = Navicula peregrina (Ehr.) Kütz.
    OK: Ehrenberg (1856)
Pinnularia rupestris Hantz.
    KS: ?Patrick & Reimer (1966)
        Synonyms:
            Navicula rupestris (Hantz.) A.S.
Pinnularia sirokiana Ehr. = ?
    OK: Ehrenberg (1856)
Pinnularia socialis (T.C. Palm.) Hust.
    KS: Wujek et al. (1980)
Pinnularia stauroptera (Grun.) Rab.
        Synonyms:
            Navicula parva (Ehr.) Elm.
            Navicula stauroptera Grun.
Pinnularia stomatophora (Grun.) Cl.
    KS: Wujek et al. (1980)
    Plains States: ?Patrick & Reimer (1966)
        Synonyms:
            Navicula stomatophora Grun.
Pinnularia subcapitata Greg.
    OK: Troeger (1978)
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula hilseana (Jan.) Jan.
            Navicula subcapitata (Greg.) Ralfs
            Navicula subcapitata var. stauroneiformis V.H.
            Pinnularia hilseana Jan.
Pinnularia subcapitata var. paucistriata (Grun.) Cl.
    OK: Troeger (1983)
Pinnularia substomatophora Hust.
    OK: Pfiester et al. (1979)
Pinnularia termes Ehr.
    OK: Ehrenberg (1856)
        Synonyms:
            Navicula thermes (Ehr.) A.S.
Pinnularia termitina (Ehr.) Patr.
    OK: Troeger (1983)
Pinnularia viridis (Nitz.) Ehr.
    KS: Harris & Eberle (2001), McFarland et al. (1964)
    NE: Ehrenberg (1856)
    OK: Ehrenberg (1856), Troeger (1978, 1983)
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Navicula viridis (Nitz.) Ehr.
Pinnularia viridis var. commutata (Grun.) Cl.
    Plains States: Patrick & Reimer (1966)
Pinnularia viridis var. minor Cl.
    KS: Wenke & Eberle (1985)
        Synonyms:
            Navicula viridis (Nitz.) Ehr. sensu A.S.
Placoneis dicephala (W. Sm.) Meresch.
        Synonyms:
            Navicula dicephala W. Sm.
Placoneis dicephala f. minor (Grun.) Cox
        Synonyms:
            Navicula dicephala f. minor Grun.
Placoneis elginensis (Greg.) Cox
    KS: Harris & Eberle (2001)
        Synonyms:
            Navicula elginensis (Greg.) Ralfs
Placoneis elginensis var. neglecta (Krasske) comb. nov.?
        Synonyms:
            Navicula elginensis var. neglecta Krasske
Placoneis exigua (Greg. ex Grun.) Meresch.
        Synonyms:
            Navicula exigua Greg. ex Grun.
Placoneis exigua var. capitata (Patr.) comb. nov.?
        Synonyms:
            Navicula exigua var. capitata Patr.
Placoneis placentula (Ehr.) Heinz.
        Synonyms:
            Navicula placentula (Ehr.) Kütz.
Placoneis placentula var. rostrata (A. Mayer) And., Stoerm., & Kreis
        Synonyms:
            Navicula placentula f. rostrata A. Mayer?
Plagiotropis arizonica Czarn. & Blinn
    KS: Czarnecki & Reinke (1981), Harris & Eberle (2001)
Plagiotropis lepidoptera (Greg.) Reim.
        Synonyms:
            Tropidoneis lepidoptera (Greg.) Cl.
Plagiotropis lepidoptera var. proboscidea (Cl.) Reim.
    KS: Harris & Eberle (2001), Wenke & Eberle (1986)
        Synonyms:
            Tropidoneis lepidoptera var. proboscidea Cl.
Planothidium dubium (Grun.) Round & Burkht.
        Synonyms:
            Achnanthes lanceolata var. dubium Grun.
Planothidium haukianum (Grun.) Round & Burkht.
        Synonyms:
            Achnanthes haukiana Grun.
Planothidium lanceolatum (Bréb.) Round & Burkht.
        Synonyms:
            Achnanthes lanceolata Grun.
Planothidium haynaldii (Istv.-Schaarsch) comb. nov.?
        Synonyms:
            Achnanthes lanceolata var. haynaldii (Istv.-Schaarsch) Cl.
Pleurosigma delicatulum W. Sm.
    CO: WPSS (1961-1963)
    KS: Curtis (1901), McFarland et al. (1964), Reinke (1985), Wenke & Eberle (1986), Williams (1962, 1964),
           WPSS (1961-1963, 1966), Wujek et al. (1980)
    NE: Williams (1962), WPSS (1961-1963, 1966)
    OK: Cooper & Wilhm (1975), Hern et al. (1979), Koch (1975), Seyfer & Wilhm (1977), Wilhm et al. (1977),
           Wilhm et al. (1978), WPSS (1961-1963)
    Plains States: Patrick & Reimer (1966)
        Synonyms:
            Gyrosigma delicatulum (W. Sm.) Elm.
Pleurosigma elongatum W. Sm.
    KS: Czarnecki & Reinke (1981), Wenke & Eberle (1986)
Pleurosigma eximium (Thw.) Cl. & Grun. = Gyrosigma eximium (Thw.) Boyer emend Sterr.
    KS: Curtis (1901)
Pleurosigma gracilentum Rab. = Gyrosigma acuminatum (Kütz.) Rab.
    KS: Curtis (1901)
Pleurosigma hippocampus Ehr. = Gyrosigma euhippus Sterr. & Ross
    KS: ?Curtis (1901)
Pleurosigma intermedium W. Sm.
    NE: Webber (1889, 1890)
Pleurosigma kuetzingii Grun. = Gyrosigma acuminatum (Kütz.) Rab.
    KS: Curtis (1901)
Pleurosigma obscurum W. Sm. emend Sterr.
        Synonyms:
            Gyrosigma obscurum (W. Sm.) Griff. & Henfr.
Pleurosigma sciotensis Sulliv. & Wormley = Gyrosigma sciotense (Sulliv. & Wormley) Cl.
    KS: Curtis (1901)
Pleurosigma spencerii (Quek.) W. Sm. = Gyrosigma acuminatum (Kütz.) Rab.
    KS: Curtis (1901)
Pleurosigma strigosum W. Sm.
    OK: Kennedy & Pfiester (1984)
Pleurosiphonia affinis Ehr. = Neidium affine (Ehr.) Pfitz.
    NE: Ehrenberg (1856)
    OK: Ehrenberg (1856)

Reimeria sinuata (Greg.) Koc. & Stoerm.
        Synonyms:
            Cymbella sinuata Greg.
Rhaphoneis rostrata Ehr. = ?
    OK: ?Ehrenberg (1856)
Rhoicosphenia curvata (Kütz.) Grun. ex Rab.
    KS: Reinke (1979a), Wenke & Eberle (1986), Wujek et al. (1980)
    NE: Andersen & Walker (1920), Elmore (1921), Hoagland et al. (1982)
    OK: Hern et al. (1979), Koch & Risser (1974), Pfiester et al. (1979), Seyfer & Wilhm (1977), 
           Wilhm et al. (1978), WPSS (1961-1963)
    Plains States: Patrick & Reimer (1966)
Rhopalodia gibba (Ehr.) O. Müll.
    KS: Harris & Eberle (2001), Reinke (1979a, 1981, 1985), Williams (1962), WPSS (1961-1963, 1966),
           Wujek (1965), Wujek et al. (1980)
    MO: Pamperl (1980), Williams (1962), WPSS (1961-1963, 1966)
    NE: Hoagland et al. (1982), F.A. Morris et al. (1979), WPSS (1961-1963)
    OK: Pfiester & Terry (1978), Pfiester et al. (1979), Seyfer & Wilhm (1977), Troeger (1978, 1983), 
          Troeger & Menzel (1986), Wilhm et al. (1978)
    Plains States: Patrick & Reimer (1975)
        Synonyms:
            Cystopleura gibba (Ehr.) DeT.
            Epithemia gibba (Ehr.) Kütz.
            Eunotia gibba Ehr.
            Navicula gibba Ehr.
Rhopalodia gibba var. ventricosa (Kütz.) H. & M. Perag. [= R. gibba var. gibba (Ehr.) O. Müll. 
      (Krammer & Lange-Bertalot 1988:159)]
    KS: Wenke & Eberle (1986)
    OK: Troeger (1983)
    Plains States: Patrick & Reimer (1975)
        Synonyms:
            Cystopleura gibba var. ventricosa (Kütz.) DeT.
            Cystopleura ventricosa (Kütz.) Elm.
            Epithemia gibba var. ventricosa (Kütz.) Grun.
Rhopalodia gibberula (Ehr.) O. Müll.
    KS: Harris & Eberle (2001), Wenke & Eberle (1985)
    OK: Koch (1975), Koch & Risser (1974), Seyfer & Wilhm (1977), Wilhm et al. (1977), Wilhm et al. (1978)
    Plains States: Patrick & Reimer (1975)
        Synonyms:
            Cystopleura gibberula (Ehr.) Kuntze
            Epithemia gibberula (Ehr.) Kütz.
            Eunotia gibberula Ehr.
Rhopalodia gibberula var. vanheurckii O. Müll.
    KS: Czarnecki & Reinke (1981)
    OK: Pfiester et al. (1979)
Rhopalodia musculus (Kütz.) O. Müll.
    KS: Harris & Eberle (2001), Wenke & Eberle (1986)
    NE: Patrick & Reimer (1975)
        Synonyms:
            Cystopleura musculus (Kütz.) Kuntze
Rhopalodia parallela (Grun.) O. Müll. [= R. gibba var. parallela (Grun..) H. & M. Perag. (Krammer & 
      Lange-Bertalot 1988:159)]
    KS: Czarnecki & Reinke (1981)
    NE: Patrick & Reimer (1975)
    OK: Kennedy & Pfiester (1984)