Metathrinca illuvialis is a moth in the Xyloryctidae family. It was described by Meyrick in 1914. It is found in India (Assam). The wingspan is about 26 mm. The forewings are whitish-ochreous, with a faint grey tinge and with the costal edge dark fuscous towards the base. There is a submarginal series of seven large black dots around the apex and termen. The hindwings are ochreous-whitish.