Tree 10-30 m. Leaves chartaceous or coriaceous, ovate-elliptic to elliptic(-oblong), rarely oblong, 10-25(-32) by 4-9(-10.5) cm, base (short-) cuneate or (broadly) rounded, apex acute-acuminate, upper surface olivaceous or brown, lower surface grey-brown, shaded by cinnamon (sub)persistent indumentum, hairs interwoven or widely spaced, scale-like, grey-brown, 0.1-0.2 mm, mixed with scattered ± dendroid brown hairs to 1 mm; Inflorescences between the leaves, ± of the Knema-type: a simple, scar-covered brachyblast 2-3 mm long, sessile or to 5 mm pedunculate, late glabrescent; Fruits single, subglobose or broadly (ob)ovoid, sometimes faintly beaked, or somewhat narrowed towards the base, 6-8 by 5-6.5 cm, hairs dense, mealy, rusty, 0.5(-l) mm long;
Asia-Tropical: New Guinea present, Bird's Head present, Japen I present, Morobe Prov present, Papua Barat present, Papua New Guinea present, Wandammen Peninsula, Idenburg R., Cycloop Mts present
Malesia: New Guinea (Papua Barat: Bird's Head, Japen I., Wandammen Peninsula, Idenburg R., Cycloop Mts; Papua New Guinea: Morobe Prov.).
1 Myristica sphaerosperma is related to M. womersleyi which is distinguishable by the longer indumentum on the lower leaf surface and fruits with a shorter stalk. Another related species is M. mediovibex, in the key placed far apart because of its smaller leaves with short indumentum below without emergent hairs, and its smaller fruits. 2 Some specimens have only a thin indumentum on the lower leaf surface, composed of scattered scale-like hairs; old leaves may become quite glabrous. Schram BW13492 (Wandammen Peninsula) has narrower and thinner leaves, and was collected at a rather low altitude for the species, c. 300 m.