Pycnarmon mallaleuca is a moth in the family Crambidae. It was described by George Hampson in 1907. It is found in the Brazilian states of Paraná and São Paulo.[1]
The wingspan is about 20 mm. Adults are pure white, the forewings with some dark points on the costa and the lines are pale yellow brown. There are traces of a discoidal spot. The hindwings have an indistinct discoidal spot and the postmedial line is excurved between veins 5 and 2, then retracted to below the end of the cell.[2]