Lithodinia c"callomonii" (Sarjeant, 1972, p.31-33, pl.5, fig.5; text-fig.6) Gocht, 1976, p.334. Holotype: Sarjeant, 1972, pl.5, fig.5; text-fig.6. NOW Meiourogonyaulax. Originally (and now) Meiourogonyaulax, subsequently Lithodinia. Age: Late Bathonian-Early Callovian.

Original diagnosis: Sarjeant, 1972, p.31-33: Meiorogonyaulax callomonii
Cyst ovoidal, with apex lost in archaeopyle formation, The "decapitated" cyst is typically broader than it is long. Tabulation ?", 0a, 6", 6c, 6""", 1p, 1"""". Plate boundaries marked by crests of very irregular form and height; when most fully developed, they are perforate, with continuous crests, and assume the appearance of branching spines connected by trabeculae. Crests may be present on the margin of the apical archaeopyle. Cingulum relatively narrow, in the form of a laevo-rotatory spiral whose two ends differ in anteroposterior position by at least twice its breadth. The posterior intercalary plate is of moderate size; plate 1""" is quite sma!l. Both plates are distinctly elongate. The sulcus is broad and extends to the antapex; the antapical plate is of moderate size.
Dimensions: Holotype- length 60 µm, breadth 67 µm. Range. length 50.5 - 70 µm (mean 59.25 µm), breadth 60 - 72 µm (mean 65. 75 µm).