Tree 5-9 m. Leaves membranous, oblong, 20-35 by 7.5-14 cm, base (short-)cuneate, rounded, or shallowly cordate, apex acute-acuminate; Inflorescences between the leaves or below, of the Knema-typt, (sub)sessile, scar-covered brachyblasts, simple or forked, to 7 by 4 mm, finely brown pubescent; Fruits in fascicles of (2-)4-7, ovoid-oblong, 3-3.5 by 1(—1.5) cm, narrowed from the middle into a narrow beak 2-3 mm (stigma remnant), base rounded, hairs dense, (red-)brown, scalelike, less than 0.1 mm;
Asia-Tropical, NW Papua New Guinea present, Sepik Prov present, upper Sepik River area endemic
Malesia: NW Papua New Guinea (endemic to the upper Sepik River area, Sepik Prov.).
The feature of a papillose lower leaf surface can be a character for species delimitation, but is possibly not valid for M. fasciculata; cf. De Wilde I.e.