Sesommata platysaris is a moth of the family Palaephatidae. It was described by Edward Meyrick in 1931.[1] It is found in the lake region in Argentina, including Lácar Lake and especially Nahuel Huapi Lake.
The length of the forewings is 4.8-6.2 mm for males and 5.4-5.6 mm for females. Adult males have dark fuscous to black wings, with a relatively large, rounded mass of broad sex scales. The forewings of the females are smooth and sometimes have a few scattered white scales. Adults are on wing from November to January in one generation per year.