Nematosphaeropsis quinquetrum (Duxbury, 1980) Stover and Williams, 1987

Now Trabeculidium. Originally (and now) Trabeculidium, subsequently (and now) Nematosphaeropsis. In this index we retain the species in Trabeculidium Duxbury, 1980, following Sarjeant, 1989, who maintained that Trabeculidium is a separate genus.

Holotype: Duxbury, 1980, pl.9, fig.2
Locus typicus: Speeton, England
Stratum typicum: Barremian

Original diagnosis: Duxbury, 1980, p.132: Trabeculodinium quinquetrum
A species of dinoflagellate cyst whose main body is pentagonal in lateral view due to its having a distinctly triangular epicyst and sharp-angled, trapeziform hypocyst. Trifurcate gonal and bifurcate parasutural processes are present and these vary in length so that despite the polyhedral shape of the main body, the cyst as a whole is spheroidal. Both gonal and parasutural processes are proximally unconnected and distally joined by solid, thin trabeculae. Each parasutural line is distally reflected by two trabeculae. The archeopyle is precingular, formed by detachment of paraplate 3".
Observed dimensions: Holotype 76x76 Ám. Overall 81(74)68x78 (70) 59 Ám.