Two-dimensional electron gases in narrow GaAs quantum wells show huge longitudinal resistance (HLR) values at certain fractional filling factors. Applying an rf field with frequencies corresponding to the nuclear spin splittings of 69Ga, 71Ga, and 75As leads to a substantial decrease of the HLR establishing a novel type of resistively detected NMR. These resonances are split into four sublines each. Neither the number of sublines nor the size of the splitting can be explained by established interaction mechanisms.