Xanthidium subtrilobum West et G.S.West 1897

    Cells solitary, as long as broad or slightly longer than broad measures 38–42 µm in length and 38–40 µm in width. Cells deeply constricted in the middle, sinus widely open and isthmus 8–12 µm. Semicells elliptic, truncated apex and straight. The lower lateral angles with a slightly divergent spine, the other angles with a pair of strongly diverging spines. Semicell face with a prominent median protrusion, the basal angles with a tubercle. Semicells elliptic in vertical view, both sides with a series of four divergent curved long spines and poles with a straight spine measures 25-40 µm in length. Semicells circular in lateral view.