Sphenoderia rhombophora Bonnet, 1966
Diagnosis: Test hyaline, ellipsoidal, very slightly compressed. Fundus relatively narrow. Pseudostome largely truncated. Neck very short, forming a lip around the narrow aperture. Covering made up of very elongated elliptical plate-scales, almost lozenge-shaped, and with low imbrication. On the neck, a montage in a highly refractive medium highlights numerous very fine circular scales, the diameter of which does not appear to exceed 2 µm.
This species differs from S. ovoidea Jung by the narrow shape of its bottom and that of the scales.
Dimensions: Length 49-52 µm; width 30-33 µm; collar 3.5 µm high; plate-scales up to 2 µm
Ecology and distribution: Mull in understory of Nothofagus procera.