Eupithecia trancasae is a moth in the Geometridae family. It is found in the region of Biobio (Nuble Province) in Chile. The habitat consists of the Northern Valdivian Forest Biotic Province. The length of the forewings is about 7.5 mm for males and 8 mm for females. The forewings are white or pale greyish white, the basal portion with pale greyish brown scaling. The hindwings are white, with grey and greyish brown scaling. Adults have been recorded on wing in December and February.