Lewis & Short

Ā̆tramītae, ārum, m., = Ἀδραμῖται, a people in the eastern part of Arabia Felix, now Hadramaut, Plin. 6, 28, 32, § 154; 12, 14, 30, § 52; cf. Mann. Arab. 79.
Hence, Ā̆tramītĭcus, a, um, adj., of or from the country of the Atramitœ, Atramitic: myrrha, Plin. 12, 16, 35, § 69.