Allosperm

They seem to have mechanisms that favour fertilization by allosperm (donated by a partner) over autosperm (produced endogenously).

The latter have a well-defined allosperm storage organ, called spermatheca, attached to their fertilization pouch (Baur, this book).

This is consistent with theory that predicts a preference for the female mating role after periods of sexual isolation because of allosperm depletion.

During copulation, the penis deposits the autosperm (which now become allosperm) into the vaginal channel of the distal hermaphroditic duct of another animal. The allosperm then travel to the spermatotheca.