From Fensome et al., 2019:
Meiourogonyaulax deflandrei Sarjeant, 1968, p.228–229, pl.1, fig.20; pl.3, fig.13; text-fig.4. Holotype: Sarjeant, 1968, pl.1, fig.20; text-fig.4. Originally (and now) Meiourogonyaulax, subsequently Lithodinia. This species is retained in Meiourogonyaulax following the retention of the genus by Riding and Helby (2001d, p.81,83). Age: late Callovian.

---------------------------------------------------------------------------------------------------

Original diagnosis: Sarjeant, 1968, p.228-229
A species of Meiourogonyaulax having a broadly ovaloid theca, the apex generally or constantly lacking and the antapex flattened to slightly concave. Tabulation ?', 0a, 6'', 6c, 5''', 2p, 1pv, 1''''. Sutures marked by low crests bearing short denticles; the denticles are occasionally linked distally by trabeculae. Shell surface densely and finely infrareticulate: the median ventral area is somewhat sunken and may lack ornament. Cingulum broad, slightly laevo-rotatory; sulcus very broad.
Dimensions: Holotype: overall length (apex lacking) 47 µm, breadth 50 µm. Range: overall length (apices lacking) 45-40 µm, breadth 50-55 µm.