The vlei rats in the genera Otomys and Parotomys are often placed in a separate subfamily , Otomyinae . They have been shown to be closely related to African murines in spite of their uniqueness . The vlei rats in the genera Otomys and Parotomys are often placed in a separate subfamily , Otomyinae , but have been shown to be closely related to African murines in spite of their uniqueness .