Hedriocystis reticulata Penard, 1904
Diagnosis: Test colorless, hyaline, polygonal in circumference; fields with rib-like edges give the shell a network-like structure; each facet with a central hole through which fine axopodia are emitted; stalk about 3 times the shell diameter; axopodia very fine; nucleus sub-centrally located.
Dimensions: Test c. 25 µm, stalk c. 70 µm, 1-1.5 µm thick.
Ecology: Fresh water; rare, in submerged Sphagnum.
Remarks: I have found this species in the Netherlands around 1980, but wasn’t able to take pictures of it. It was placed in the genus Penardiophrys by Mikrjukov (2000), but more research is needed to reconsider its taxonomic position.