Clinodiplosis bellum sp. nov. associated with Diplopterys pubipetala (A.Juss.) Anderson and Davis (Malpighiaceae) from Brazil are described. This is the first species of Clinodiplosis described to State of São Paulo and the first formal description of Diplopterys pubipetala (Malpighiaceae) as host plant of Cecidomyiidae species. Description and illustration of the Clinodiplosis bellum sp. nov. (Diptera: Cecidomyiidae) are given.