Passalurus ambiguus

Pas·sal·u·rus am·big·u·us

(pa-sal'yū-rŭs am-big'yū-ŭs),
The rabbit pinworm, an oxyurid nematode found abundantly in the cecum and large intestine of rabbits.

Passalurus

a genus of nematodes in the family Oxyuridae.

Passalurus ambiguus
found in the cecum and colon of rabbits, hares and other lagomorphs. They appear to be harmless even in very large numbers.