Trinematidae Hoogenraad & De Groot 1940, emend Adl et al. 2012
Test with bilateral symmetry; scales oval or round, sometimes of both types; specialized tooth-shaped scales around the aperture; aperture invaginated in some taxa.
Corythion, Playfairina, Puytoracia, Trinema.
Sphenoderiidae Chatelain et al, 2013
Test with self-secreted circular to elliptical silica scales of different sizes and shapes, but without indentations; pseudostome surrounded with small round or oval scales; usually its ventral side shorter.
Sphenoderia, Trachelocorythion.
Paulinellidae De Saedeleer 1934, emend. Adl et al. 2012
Pyriform, uncompressed shape; scales, when present, long, with length perpendicular to aperture. At least two genera (Ovulinata, Micropyxidiella ) with totally organic test without silica scales.
Ovulinata, Paulinella, Micropyxidiella.