Description
Cells armored, elongated, with a pentagonal to pyriform shape in ventral
and dorsal views, moderately dorsoventrally compressed, and with
slightly convex lateral sides of the epitheca and hypotheca (Figs 2a, b,
d–f, and 4a–b). The epitheca is tapering into a robust apical horn,
which is slightly shorter than antapical horns (Figs 2a, e–f, and
4a–b). The first apical plate 1’ is symmetrical and orthogonal, with
its proximal margins being the longest (Figs 2a–b, e, and 4a). The
quadrangular 1a plate is the smallest apical intercalary plate (Figs 2h,
and 4b, d). The plate 2a is asymmetrical and pentagonal, slightly
shifted to the left (Figs 2d, h, and 4b, d). The pentagonal 3a plate is
about triple the area of plate 1a (Figs 2d, h, and 4b, d), and the
fourth precingular plate (4”) is trapeziform (Figs 2d, h, and 4b, d).
The cingulum is equatorial, displaced, descending by about 0.5–0.75
cingular width (Figs 2a–b, e, and 4a), not excavated, moderately
inclined relative to the equatorial plane of the cell, and bears
prominent smooth cingular lists (Figs 2e–f). The broad sulcus is
shallow and somewhat oblique, bordered by sulcal lists (Figs 2a, e, and
4a). The hypotheca possesses two long antapical horns, slender and
slightly divergent (the right one slightly longer than the left) ending
in sharp tips (Figs 2a, e–f, and 4a–c). The distance between the tips
of the antapical horns is narrower than the cell’s width (Figs 2a, e–f,
and 4a–b). The theca is faintly reticulated with incomplete meshes and
two kinds of pore sizes (Fig. 2g). Dimensions : length 143 ± 2 µm
(min. 140 µm, max. 145 µm, n = 30), width 61 ± 1 µm (min. 60 µm, max. 63
µm, n = 30), and depth 37 ± 2 µm (min. 35 µm, max. 40 µm, n = 30).