Prostoma graecense is a species of Nemertea in the family Prostomatidae.

Individuals in this species can reach up to a length of 5 cm.

[4] It has been reported in Japan, Russia, New Zealand, Kenya,[7] Venezuela, Argentina, and Mexico.

[5] Genetic evidence indicates this species was introduced by humans.

[8][clarification needed] It is the only known species of fresh water Nemertea in Australia.