Microdinium echinatum Clarke and Verdier, 1967

Tax. jr. synonym of Microdinium setosum Sarjeant, 1966, according to Clarke et al., 1968.
Holotype: Clarke and Verdier, 1967, pl.1, fig.9
Locus typicus: Isle of Wight, England
Stratum typicum: Cenomanian

Original diagnosis: Clarke and Verdier, 1967, p.64
A species of Microdinium possessing relatively high ledges ornamented with echinae of regular height. Plates sculptured with granae or rugulae.

Original description: Clarke and Verdier, 1967, p.64-65
Outline rounded polygonal. A distinct transverse girdle divides the body into two unequal parts; the epitheca being smaller than the hypotheca.
The girdle is interrupted ventrally and slightly displaced. Tabulation is well displayed and appears to have the same number and pattern reported in the generic diagnosis of Microdinium except for the addition of cingular plates. The plates are bordered by well developed denticulate ledges. The denticles are in the form of sharp spines of equal height and spacing. Sculpture of the plates consists of granae or rugulae. An apical archaeopyle is visible on nearly all specimens and often the apical portion is still attached although displaced.

Measurements:HolotypeRange
Overall length33 Ám28-34 Ám
Overall breadth30 Ám26-32 Ám
Width of girdle5 Ám4- 5 Ám
Height of ledges3 Ám2- 3 Ám
Height of spines2 Ám1- 2 Ám

Affinities:
Clarke and Verdier, 1967, p.65: M. echinatum differs from M. irregulare and M. ornatum in the possession of denticulate (echinate) ledges.