Dumbletonius unimaculata is a species of moth of the family Hepialidae. It is endemic to New Zealand. The wingspan is 51–67 mm for males and 74–90 mm for females. The colour pattern of the forewings is complex in males and usually reduced or obsolete in female. The hindwings are unicolorous yellow, orange-yellow or pink. Adults are on wing from December to April. The larvae probably feed on fallen leaves.