The species of the genus Arinia (Diplommatinidae) occurring on Borneo are revised. Altogether, 24 species and 5 subspecies are distinguished; all except three are new, and all are endemic to Borneo. The present paper completes the revision of the Bornean Diplommatinidae (see Vermeulen 1991, 1993, 1994, 1996). A few additions and emendations, made necessary by some material collected since the revisions of the genera Diplommatina and Opisthostoma, have therefore been added. The additions include three new taxa in the genera mentioned.