| Biddulphia subaequa (Kütz.) Ralfs, 1861 |
| Biddulphia tridens (Ehrenb.) Ehrenb., 1840 |
| Biddulphia tripartita (Grunow) Van Heurck |
| Biddulphia tuomeyi (Bailey) Roper, 1859 |
| Biddulphiaceae Kütz., 1844 |
| Isthmia C. Agardh, 1832 |
| Isthmia capensis Grunow, 1888 |
| Isthmia enervis Ehrenb., 1836 |
| Isthmia nervosa Kütz., 1844 |
| Neohuttonia Kuntze, 1898 |
| Neohuttonia reichardtii (Grunow) Kuntze, 1898 |
| Pseudotriceratium Grunow, 1884 |
| Pseudotriceratium punctatum (Wall.) Simonsen, 1974 |
| Terpsinoë Ehrenb., 1843 |
| Terpsinoë americana (Bailey) Grunow, 1868 |
| Terpsinoë intermedia Panlocsek |
| Terpsinoë musica Ehrenb., 1843 |
| Trigonium Cleve, 1867 |
| Trigonium alternans (Bailey) D.G. Mann, 1907 |
| Trigonium arcticum (Brightw.) Cleve, 1868 |