Circulodinium hirtellum, Alberti, 1961

Originally (and now) Circulodinium, subsequently Canningia, thirdly Cyclonephelium.
Davey, 1978, transferred this species to Cyclonephelium Deflandre and Cookson, 1955. Helby, 1987, retained the species in Circulodinium.
Possible tax. jr. synonym of Tenua (as Cyclonephelium) hystrix Eisenack, 1958, according to Backhouse, 1988.

Holotype: Alberti, 1961, pl.4, fig.20
Locus typicus: Haverlahwiese, Germany
Stratum typicum: Valanginian-Hauterivian

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Original description: [Alberti, 1961, p.28] (Translation: LPP):

Diagnosis:
Shell flattened, outline irregularly rounded, slightly longer than broad. Short apical protrusion. Two antapical bulges of unequal size. Epitheca slightly smaller than hypotheca. Surface of shell, except central parts of dorsal and ventral sides, covered with short, pointed, thorn-like spines.

Description:
Short, blunt apical horn (c. 7 µm). Two rounded antapical horns of unequal size. The length and distribution of the at the bases broadened thorns variable. Membrane yellow-brown and transparent.

Dimensions:
Holotype - length 102 µm, breadth 93 µm, length of thorns 3-4 µm, length of apical horn 7 µm, antapical bulges 10-12 µm.
Range - length 98-106 µm, breadth 88-97 µm.