Mrabella plicata (Hoogenraad and De Groot, 1940)
Diagnosis: Test made of small square plates, between which some irregularly polygonal or round ones often are present.
Test generally elongated pyriform. On one third of the length of the shell, at the transition from the neck to the main body, there is swelling on both sides of the surface of the shell, which marks the location of a lateral pore. This is where a bulge-like outline of the fundus originates. This keel gives the shell surface a more or less folded appearance, to which the species name “plicata” refers. In lateral view, the keel shows itself as a tapering of the fundus. The platelets forming the shell do not reach the edge of the mouth; like Q. tropica, this is bordered by a narrow chitinous rim.
Dimensions: Length 111-135 µm; width 49-62 µm.
Ecology: Hoogenraad and De Groot (1940) found this species “in quite large numbers” near Kerintji, Indonesia. “Mrabella plicata was found along with Q. tropica. However, it was not connected to this species by transitions of the shell shape and the size of the two species formed well-separated populations.”