Gamasellus onitiae sp. nov. (Ologamasidae: Mesostigmata) has been identified and described after being been collected from a dung beetle, Onitis philemon (Scarabaeidae, Coleoptera), in India. The specimen was found to be attached via a claw to the head region of the beetle. The mite–beetle association appeared to be phoretic. The distal setae, ventral setae, sternal shield length, and peritreme of G. onitiae sp. nov. differ from those of the closely related Gamasellus falciger (G. Canestrini & R. Canestrini), Gamasellus deepdelensis (Ryke), Gamasellus racovitzai (Jumeau and Usher), and Gamasellus bellavistae Emberson.