4) Monocystis arcuata Boldt, 1910

Infested organ. Seminal vesicles

Type host. Lumbricus castaneus, L. rubellus and Eisenia foetida

Type locality. The United Kingdom

Description. Elongated curved, bow shaped characterized with a small hemispherical projection and measures 90 − 620 µm × 14 − 30 µm. Nucleus ovoid and varies from 6 × 5 µm to 28 × 9µm.