Tree 20 m. Leaves thinly chartaceous (but conspicuously brittle when dry), elliptic-oblong, 7-12 by 3-5.5 cm, base short-attenuate to broadly rounded, apex broadly acute(-acuminate) with blunt tip; Inflorescences among the leaves, glabrescent, hairs 0.1-0.2 mm;
Asia-Tropical, SE Papua Barat present, border of Western Prov. in Papua New Guinea: at Ingembit, road to Opka present
Malesia: SE Papua Barat (border of Western Prov. in Papua New Guinea: at Ingembit, road to Opka), known only from the type.
Noticeable for a number of unique features: small leaves with faint nerves, blades glabrous below with neither dots nor papillae, inflorescences pedunculate, perianths small, 4 mm. The leaves dry conspicuously dark, to a blackish brown colour. Superficially M. atrescens resembles M. tristis, but that species has sessile inflorescences, larger male perianths and a (partly) pubescent androphore. The androphore in M. atrescens, as seen in the boiled-up flowers, has a peculiar warty-bullate surface, which may be an artefact.