Hemithea nubigena Wollaston, 1858 was described from Madeira where it occurred in abundance in the Erica-woods at the highest altitudes of the island, even on the extreme summit of the Pico Ruivo (1830 m a.s.l.). The species is still common in these localities, but has never been found outside Madeira. It is now transferred to the genus Xenochlorodes Warren, 1897. No other pure green-coloured species of Geometridae are known from Madeira. Pinker (1971) depicts a large green ♀ specimen of Geometridae from Madeira (Serra d'Agua) measuring 28 mm in wing expanse, compared with 15-20 mm in normal X. nubigena. Even so, Pinker regards this specimen as an abnormally developed giant of nubigena. Examination of new material (22 specimens), shows the large specimens to belong to a distinct species, described here as Xenochlorodes magna n.sp.