(Pouchet) Kofoid (1911: 214, pl. 9, figs 1–5)
Protoperidinium digitale Pouchet (1883: 443, pl. 18, fig. 14)
Dodge (1982: 208, fig. 26A; pl. 6c, d)
Cells rhomboidal, 50–75 µm long, 35–50 µm diameter. Thecae thick, with large deep pores scattered over the surface; epitheca triangular with ±straight sides grading into a short apical horn; hypotheca rounded, with slightly convex sides, with 2 antapical spines, the left spine longer than the right. Cingulum c. 5 µm wide, displaced by 2–2.5 cingular widths; cingular lists absent or greatly reduced, narrow, projected laterally. Sulcus deep, extending from apex to antapex; sulcal lists narrow. Chloroplasts present.
Southern Ocean, 50–62°S, south of Australia; Southern Ocean, near South Georgia (Dodge & Priddle, 1987); Ross Sea (Watanabe, 1982).
Gonyaulax digitale typically has epithecal shoulders and a moderate apical horn.