Phyllonorycter pygmaea is a moth of the family Gracillariidae. It is known from Japan (the islands of Hokkaidō, Kyūshū, Shikoku and Honshū), Korea and the Russian Far East.[1]
The wingspan is 5-5.5 mm.
The larvae feed on Castanea crenata, Quercus acutissima, Quercus crispula, Quercus mongolica and Quercus serrata. They mine the leaves of their host plant.