Achnanthes conspicua var. conspicua A.Mayer, 1919 (original description)
Achnanthidium lanceolatum var. rhomboidale Mayer, 1919 (original description)
Achnanthidium lanceolatum var. rostellatum ‘Hustedt' according to Mayer (taxonomy source)
Amphora coffeaeformis var. thumensis Mayer, 1919 (original description)
Anomoeoneis exilis f. subacuminata Mayer, 1919 (original description)
Anomoeoneis exilis var. genuina Mayer, 1919 (original description)
Anomoeoneis exilis var. lanceolata Mayer, 1919 (original description)
Caloneis alpestris sensu Mayer, 1919 (original description)
Caloneis alpestris var. genuina Mayer, 1919 (original description)
Caloneis alpestris var. lanceolata Mayer, 1919 (original description)
Ceratoneis arcus f. undulata Mayer, 1919 (original description)
Ceratoneis arcus var. incisa Mayer, 1919 (original description)
Cocconeis flexella var. appendiculata Mayer, 1919 (original description)
Cocconeis thumensis A.Mayer, 1919 (original description)
Cyclotella comta f. evidenterpuctata Mayer, 1919 (original description)
Cyclotella comta var. ovalis (Fricke) Mayer, 1919 accepted as
Cyclotella ovalis Fricke in Schmidt et al., 1906 (new combination reference)
Cyclotella melosiroides var. clavigera Mayer, 1919 (original description)
Cymbella aequalis var. genuina Mayer, 1919 (original description)
Cymbella aequalis var. platycephala Mayer, 1919 (original description)
Cymbella aequalis var. subaequalis (Grunow) Mayer, 1919 accepted as
Cymbella subaequalis Grunow, 1880 (new combination reference)
Cymbella amphicephala var. genuina Mayer, 1919 (original description)
Cymbella angustata var. capitata Mayer, 1919 (original description)
Cymbella delicatula var. captitata Mayer, 1919 (original description)
Cymbella leptoceras f. curta Grunow (taxonomy source)
Cymbella leptoceros f. genuina Mayer, 1919 (original description)
Cymbella leptoceros f. minor Mayer, 1919 (original description)
Cymbella microcephala var. rostellata Mayer, 1919 (original description)
Cymbella rupicola var. genuina Mayer, 1919 (original description)
Cymbella rupicola var. rostrata A.Meyer, 1919 (original description)
Denticula tenuis var. genuina Mayer, 1919 (original description)
Diatoma tenue var. inflata Mayer, 1919 (original description)
Diatoma vulgare f. tenuicollis Mayer, 1919 accepted as
Diatoma vulgaris f. tenuicollis Mayer, 1919 (original description)
Diploneis didyma f. linearis Mayer, 1919 (original description)
Diploneis didyma f. subinflata Mayer, 1919 (original description)
Diploneis didyma f. typica Mayer, 1919 (original description)
Fragilaria brevistriata var. linearis Mayer, 1919 (original description)
Fragilaria construens f. subrotunda Mayer, 1917 (new combination reference)
Fragilaria construens f. undulata Mayer, 1919 (original description)
Fragilaria construens var. subrotunda (Mayer) Mayer, 1919 (new combination reference)
Fragilaria gracillima var. gracillima Mayer, 1919 (original description)
Fragilaria pinnata var. inflata A.Mayer, 1919 (original description)
Fragilaria pinnata var. intermedia (Grunow) Mayer, 1919 accepted as
Staurosira intermedia (Grunow) Grunow, 1882 accepted as
Fragilaria mutabilis var. intermedia Grunow, 1862 accepted as
Fragilaria intermedia (Grunow) Grunow in Van Heurck, 1881 (new combination reference)
Fragilaria pinnata var. parallela A.Mayer, 1919 (original description)
Gomphonema angustatum f. breve Mayer, 1919 (original description)
Gomphonema insigne f. lusus cymbelliforme Mayer, 1919 (original description)
Gomphonema insigne var. undulatum Mayer, 1919 (original description)
Gomphonema intricatum var. pusillum Mayer, 1919 (original description)
Gomphonema intricatum var. semiaperta Mayer, 1919 (original description)
Gomphonema olivaceum f. dubia Mayer, 1919 (original description)
Gomphonema olivaceum f. minores Mayer, 1919 (original description)
Gomphonema olivaceum f. minutulum (Mayer) Mayer, 1919 (new combination reference)
Gomphonema olivaceum var. inflata (Mayer) Mayer, 1919 (new combination reference)
Gomphonema parvulum f. genuinum Mayer, 1919 (original description)
Gomphonema subclavatum var. commutatum (Grunow) Mayer, 1919 accepted as
Gomphonema commutatum f. commutatum Grunow in Van Heurck, 1880 (new combination reference)
Gomphonema subclavatum var. genuinum Mayer, 1919 (original description)
Gomphonema subclavatum var. medium Mayer, 1919 (original description)
Gomphonema subclavatum var. tenellum Mayer, 1919 (original description)
Hantzschia amphioxys var. elongata sensu Mayer, 1919 (original description)
Navicula bacilliformis var. genuina Mayer, 1919 (original description)
Navicula bacilliformis var. neglecta Mayer, 1919 (original description)
Navicula cincta var. angusta sensu Mayer, 1919 (original description)
Navicula cincta var. genuina Mayer, 1919 (original description)
Navicula dicephala var. genuina Mayer, 1919 (original description)
Navicula dimidiata A.Mayer, 1919 (original description)
Navicula graciloides A.Mayer, 1919 (original description)
Navicula gregaria var. rostellata Mayer, 1919 (original description)
Navicula involuta Mayer, 1919 (original description)
Navicula laeta A.Mayer, 1919 (original description)
Navicula peregrina f. acuta Mayer, 1919 (original description)
Navicula placentula var. genuina Mayer, 1919 (original description)
Navicula pusio sensu Mayer, 1919 (original description)
Navicula tuscula var. genuina Mayer, 1919 (original description)
Navicula tuscula var. rostrata sensu Mayer, 1919 (original description)
Neidium dubium f. genuinum Mayer, 1919 (original description)
Neidium dubium var. peisonis (Grunow) Mayer, 1919 accepted as
Navicula peisonis var. peisonis Grunow, 1860 (new combination reference)
Neidium tenellum Mayer, 1919 (original description)
Nitzschia amphibia var. genuina Mayer, 1919 (original description)
Nitzschia amphibia var. intermedia Mayer, 1919 (original description)
Nitzschia amphioxys var. amphilepta (Grunow) Mayer, 1919 accepted as
Hantzschia amphioxys var. amphilepta Grunow, 1880 (new combination reference)
Nitzschia microcephala var. impressa Mayer, 1919 (original description)
Surirella gracillima Mayer, 1919 (original description)
Surirella ovalis f. ovata (Kützing) Mayer, 1919 accepted as
Surirella ovata f. ovata Kützing, 1844 (new combination reference)
Surirella thumensis A.Mayer, 1919 (original description)
Synedra delicatula Ant.Mayer, 1919 (original description)
Synedra ulna f. bicurvata (Biene) Mayer, 1919 accepted as
Synedra bicurvata Biene ex Rabenhorst, 1864 (new combination reference)
Synedra vaucheriae f. brevis Mayer, 1919 (original description)
Synedra vaucheriae f. lanceolata Mayer, 1919 (original description)
Synedra vaucheriae f. typica Mayer, 1919 (original description)
Synedra vaucheriae var. rhomboidalis Mayer, 1919 (original description)
Synedra vaucheriae var. undulata Mayer, 1919 (original description)