Pycnarmon marginalis is a moth in the Crambidae family. It was described by Snellen in 1890. It is found in India (Sikkim) and Taiwan. The wingspan is about 20 mm. Adults are glossy white, the forewings with black spots at the base of the costa and vein 1 and with subbasal and antemedial larger spots on the costa, as well as a diseocellular spot. The postmedial line is strongly marked and outwardly oblique from the costa to vein 2, then obsolescent and retracted to below the angle of the cell. The hindwings have a discocellular spot and the postmedial line is nearly straight from costa to vein 2, then retracted to below the angle of the cell. Both wings have a very prominent broad black marginal line.