Macroglossum tenebrosa is a moth of the family Sphingidae. It is known from Sulawesi, the Moluccas, Aru, Papua New Guinea, the Bismarck Archipelago, the Solomon Islands and north-eastern Australia. The head and thorax uppersides are green. The abdomen upperside tergites are glossy bluish grey when side lit, apart from some black patches. There are no white side patches. The tips of the lateral tufts are white. The scales of the anal brush are usually tipped with buffish white, but sometimes largely black with the tips faintly tawny, sometimes all black in specimens from Queensland. The underside of both wings is bluish white basally. The hindwing upperside is bluish white near the anal angle, with a bluish white streak.