Synopsis of the species of Monocystis von Stein, 1848 (Apicomplexa: Gregarinomorphea: Arthrogregarida) pathogenic to earthworms described so far.

A synopsis of the species of Monocystis (Apicomplexa: Gregarinomorphea: Arthrogregarida) is presented, including a total of 114 species of worldwide. The most significant morphological and morphometric traits for each species are included together with information on the type-host, type locality, the infection site within the host and the original references. This checklist enumerates total Monocystis spp. in a place described so far in the worldwide pattern.