Orthonama obstipata, the gem, is a moth of the family Geometridae. The species was first described by Johan Christian Fabricius in 1794. It is a cosmopolitan species. In continental Europe though in the northeast, its range does not significantly extend beyond the Baltic region and it is absent from northern Russia. This well-flying species is prone to vagrancy and able to cross considerable distances of the open sea; it can thus be regularly found on the British Isles (though mainly in the south) and even on Iceland.

Under its junior synonyms Nycterosea brunneipennis and Geometra fluviata, the gem is the type species of genera Nycterosea and Percnoptilota, respectively. The latter is treated as a junior synonym of the former, but Nycterosea, though usually included in Orthonama these days, may warrant recognition as an independent genus after all.

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