An interesting group of testate amoebae is the genus Difflugia. There have been described hundreds of species, but the question is: how many of them are true species? Most descriptions are inaccurate of just based on one single test. Probably this group consists of several genera. Only DNA sequencing can help here. One of my projects is to make a visual map of all known species. It’s one of the most difficult taxa to identify.
M. plicata, after Hoogenraad and De Groot, 1940 Mrabella plicata (Hoogenraad and De Groot, 1940) Diagnosis: Test made of small square plates, between which some
Q. alata, after Gauthier-Lièvre, 1957 Quadrulella alata Gauthier-Lièvre, 1957 Diagnosis: In frontal view, the test is lageniform, with a broadly rounded fundus (subcircular or ovoid)
Quadrulella acuminata, after Van Oye, 1958 Quadrulella acuminata Van Oye, 1958 Diagnosis: Test rather pyriform with a stretched base with converging sides, very slightly concave
H. gigantea, after De Graaf, 1952 Hyalosphenia gigantea De Graaf, 1952 Diagnose: The theca is perfectly hyaline as in all other species of the genus.