Gomphonema acuminatum f. acuminatoides Mayer, 1928 (original description)
Gomphonema acuminatum f. brebissoniformis Mayer, 1928 (original description)
Gomphonema acuminatum f. typica (Ehrenberg) Mayer, 1928 accepted as
Gomphonema trigonocephalum Ehrenberg, 1854 (new combination reference)
Gomphonema angustatum f. typica Mayer, 1928 (original description)
Gomphonema angustatum f. undulata (Grunow) Hustedt, 1942 accepted as
Gomphonema angustatum var. undulata Grunow ms. in Cleve, 1894 (new combination reference)
Gomphonema angustatum var. naviculiformis Mayer, 1928 (original description)
Gomphonema augur f. pusilla Mayer, 1928 (original description)
Gomphonema augur f. typica Mayer, 1928 (original description)
Gomphonema constrictum f. italicum (Kützing) Mayer, 1928 accepted as
Gomphonema italicum Kützing, 1844 (new combination reference)
Gomphonema constrictum f. obliqua Mayer, 1928 (original description)
Gomphonema constrictum f. robusta Mayer, 1928 (original description)
Gomphonema constrictum f. typica Mayer, 1928 (original description)
Gomphonema constrictum f. ventricosa (Gregory) Mayer, 1928 accepted as
Gomphonema ventricosum f. ventricosum Gregory, 1856 (new combination reference)
Gomphonema gracile var. intricatiformis Mayer, 1928 (original description)
Gomphonema helveticum f. incurvatum (Brun) Mayer, 1928 accepted as
Gomphonema helveticum var. incurvatum Brun, 1895 (new combination reference)
Gomphonema helveticum var. genuina Mayer, 1928 (original description)
Gomphonema helveticum var. undulatum Mayer, 1928 (original description)
Gomphonema insigne var. elongatum Mayer, 1928 (original description)
Gomphonema insigne var. fossilis Mayer, 1928 (original description)
Gomphonema insigne var. genuinum Mayer, 1928 (original description)
Gomphonema insigne var. inaequalis Mayer, 1928 (original description)
Gomphonema insigne var. subaequale Mayer, 1928 (original description)
Gomphonema insigne var. subclavatiformis Mayer, 1928 (original description)
Gomphonema intricatum f. pusilla (Mayer) Mayer, 1928 accepted as
Gomphonema intricatum var. pusillum Mayer, 1919 (new combination reference)
Gomphonema intricatum f. semiaperta Mayer, 1928 (original description)
Gomphonema intricatum f. semipura Mayer, 1928 (original description)
Gomphonema intricatum f. subcapitata Mayer, 1928 (original description)
Gomphonema intricatum f. typica Mayer, 1928 (original description)
Gomphonema intricatum var. dichotomiformis Mayer, 1928 accepted as
Gomphonema dichotiforme Z.X.Shi, 2004 (original description)
Gomphonema intricatum var. dichotomum Mayer, 1928 (original description)
Gomphonema montanum f. abnormis Mayer, 1928 (original description)
Gomphonema montanum f. subaequalis Mayer, 1928 (original description)
Gomphonema montanum f. typica Mayer, 1928 (original description)
Gomphonema montanum var. acuminata (M. Peragallo & Heribaud in Heribaud) Mayer, 1928 accepted as
Gomphonema subclavatum var. acuminata M.Peragallo & Héribaud, 1893 (new combination reference)
Gomphonema montanum var. mustela (Ehrenberg) Mayer, 1928 (new combination reference)
Gomphonema olivaceum f. subramosa (Agardh) Mayer, 1928 accepted as
Gomphonema subramosum var. subramosum Agardh, 1831 (new combination reference)
Gomphonema olivaceum f. typica Mayer, 1928 (original description)
Gomphonema parvulum f. semiaperta Mayer, 1928 (original description)
Gomphonema parvulum var. aequalis Mayer, 1928 (original description)