Thenaria (Acontiaria) with mesogloeal sphincter. Mesenteries not differentiated into macro- and microcnemes. Acontia with microbasic amastigophors and basitrichs.
Definitions and contained taxa are those of Oscar Carlgren as published in 1949 : Kungl Svenska Vetenskapsakadamiens Handlingar, Series 4, Volume 1, Number 1