A nematode genus of the family Stephanofilariidae (superfamily Filarioidea). Adults are long and thin, typically occur in the peritoneal cavity, and produce sheathed microfilariae in the blood that are transmitted to other hosts after cyclic development in appropriate mosquito hosts. They are parasitic in cattle or equines (wild or domestic) and generally are nonpathogenic, although occasionally young worms may wander into the anterior chamber of the eye. [L. seta, a bristle]