D.M.Williams 1985
Meridion circulare has markedly heteropolar valves.
Odontidium mesodon has more elliptic valves and a higher stria density.
The costae of Odontidium hyemale are oriented diagonally.
(Ehrenb.) Kütz. 1844
(Grev.) C.Agardh 1831
(Roth) Kütz. 1844