Tree 25-30 m. Leaves chartaceous (to thinly coriaceous), oblong-lanceolate, 6-15 by 1.5-3.5 cm, gradually narrowed to the acute apex, base broadly attenuate or rounded; Inflorescences between and below the leaves, sometimes on the older wood, of the Knema-type, brachyblast sessile, short, simple, to 3 mm, densely rusty pubescent, with 5-15 flowers in a loose apical cluster, buds ± equal in size; Fruits not seen, fructescences probably with several fruits, judged from the many-flowered female inflorescences.
Asia-Tropical, Bird's Head: Warsamson River valley, E of Sorong present, Central New Guinea present, Papua New Guinea present, West New Guinea present, upper Fly River area present
Malesia: Central New Guinea (Papua New Guinea: upper Fly River area); West New Guinea (Bird's Head: Warsamson River valley, E of Sorong).
Myristica atrocorticata is known only from a female flowering specimen and two male flowering specimens with immature flowers; fruits are not known. It resembles the variable and widespread M. tristis but is readily distinguishable by the conspicuously cracking blackish bark of the older twigs, the comparatively long petioles, the faint nervation, and the late glabrescent undersurface of the leaves with inconspicuous minute scale-like hairs (but especially densely haired in Brass 7079). Superficially the present species may be confused with M. firmipes. Myristica inundata is similar as well; for differences see under that species.