Hypnodinium

甲藻門Dinophyta

雙鞭藻綱Dinophyceae

植甲藻目 Phytodiniales

植甲藻科 Phytodiniaceae

厚甲藻屬Tetradinium

描述：球形、浮游S金色細胞。有殼和溝、眼點，無鞭毛; 殼面緊閉。孢子生殖velope closely appressed. This genus may be the cyst stage of a motile species, may be part of the history of Cystodinium (zygote), or may be valid since reproduction via aplanospores was observed.