Microornamentation of Lioestheria, Mimoleaia, and Echinolimnadia (conchostraca) from the terminal Permian of Siberia

Previously unknown minute ornamentation patterns of conchostracans are described based on SEM investigation of several collections from the terminal Permian volcanic deposits of the Tunguska Syneclise. Lioestheria (Lioestheriidae) shows ovally elongated cells arranged in rows along the growth bands, Mimoleaia (Leaiidae) has large polygonal cells with double walls, and Echinolimnaia (Echinolimnadiidae fam. nov.) displays a pattern with small polygonal cells bearing small spines along their walls. Diagnoses of genera and species are refined. New data about their distribution are presented.