Anomoeoneis sculpta var. apiculata Frenguelli, 1926 (original description)
Anomoeoneis sculpta var. minima Frenguelli, 1926 (original description)
Anomoeoneis sculpta var. ornata (Frenguelli) Frenguelli in Auer, 1959 (original description)
Campylodiscus clypeus f. minor (Pantocsek) Frenguelli, 1926 accepted as Campylodiscus clypeus var. minor Pantocsek, 1912 (new combination reference)
Fragilaria construens var. trigibba (Pantocsek) Frenguelli, 1926 accepted as Fragilaria trigibba Pantocsek, 1902 (new combination reference)
Fragilaria peragalli Frenguelli, 1926-1928 (original description)
Gomphonema berggrenii var. capitata Frenguelli, 1926 (original description)
Gomphonema cruciferum Frenguelli, 1926 (original description)
Gomphonema subclavatum var. fossilis Frenguelli, 1926 (original description)
Hantzschia amphioxys var. exilis Frenguelli, 1926 (original description)
Hantzschia faba Frenguelli, 1926 (original description)
Hantzschia limi var. limi Frenguelli, 1926 (original description)
Hantzschia limi var. minor Frenguelli, 1926 (original description)
Hyalodiscus schmidtii Frenguelli, 1926 (original description)
Navicula affinis f. minor Frenguelli, 1924 (original description)
Navicula brevistriata (van Heurck) Frenguelli, 1926 accepted as Navicula gibba var. brevistriata van Heurck, 1885 (new combination reference)
Navicula columnaris var. undulata Frenguelli, 1926 (original description)
Navicula divergens f. major Frenguelli, 1926 (original description)
Navicula divergens f. minor Frenguelli, 1926 (original description)
Navicula divergens var. laticeps Frenguelli, 1926 (original description)
Navicula doeringii var. undulata Frenguelli, 1926 (original description)
Navicula magellanica var. minor Frenguelli, 1926 (original description)
Navicula major f. minor Frenguelli, 1926 (original description)
Navicula pampeana Frenguelli, 1926 (original description)
Navicula pampeana var. major Frenguelli, 1926 (original description)
Navicula pampeana var. minor Frenguelli, 1926 (original description)
Navicula pampeana var. pampeana Frenguelli, 1926 (original description)
Navicula peregrina f. fossilis (Héribaud) Frenguelli, 1926 accepted as Navicula peregrina var. fossilis Héribaud, 1903 (new combination reference)
Navicula polygramma f. elliptica Frenguelli, 1926 (original description)
Navicula polygramma f. lanceolata Frenguelli, 1926 (original description)
Navicula subovalis var. major Frenguelli, 1926 (original description)
Navicula subovalis var. minor Frenguelli, 1926 (original description)
Nitzschia amphibia var. acuta Frenguelli, 1926 (original description)
Nitzschia amphioxys var. exilis Frenguelli, 1926 (original description)
Nitzschia faba Frenguelli, 1926 (original description)
Nitzschia limi Frenguelli, 1926 (original description)
Nitzschia limi var. limi Frenguelli, 1926 (original description)
Nitzschia limi var. minor Frenguelli, 1926 (original description)
Stauroneis acuta var. inflata (Heiden in Schmidt et al.) Frenguelli, 1926 accepted as Stauroneis inflata Heiden in Schmidt et al., 1903 (new combination reference)
Surirella fortii Frenguelli, 1926 (original description)