Dimorphocalyx moluccensis Welzen & Oostrum, 2015

5. Dimorphocalyx moluccensis Welzen & Oostrum View in CoL , sp. nov. — Map 1

Dimorphocalyx cf. muricatus auct. non (Hook.f.) Airy Shaw:Airy Shaw, Kew Bull. 37 (1982) 16.

Resembles D. denticulatus most closely in the hairy disc and petals and D. muricatus in the long inflorescences, but differs from both in having leaves larger, with relatively long petiole and at most an acuminate apex; and staminate flowers smaller. — Type: De Vogel 3134 (holo L), Indonesia, N Moluccas, Halmahera, Ekor, side of Gunung Panjang.

Trees to 12 m high, dbh to 28 cm, one specimen fluted, flutes c. 4 m high, c. 2 m out and c. 5 cm wide; flowering branches 2.5–3 mm thick, round, glabrous. Indumentum of light yellow hairs, most parts glabrous. Outer bark brownish grey, not fissured, c. 0.2 mm thick; inner bark red, c. 3 mm thick, without exudate; sapwood pale yellow tinged violet, gradually passing into the darker yellow heartwood. Stipules triangular, 4–4.5 by c. 3.5 mm, thick, margins thinner, outside glabrous to hairy, inside glabrous, caducous. Leaves: petiole 0.8–2 cm long, 1.5–3 mm diam, above flat to furrowed, glabrous to few hairs, completely pulvinate; lamina elliptic to oblong, widest in ± middle, 10.5–24.5 by 5.8–12.8 cm, 1.8–1.9 times as long as wide, (rather) coriaceous, base rounded to attenuate, margin laxly serrulate, with glands in the teeth abaxially, recurved, apex acute to acuminate, mainly glabrous, venation slightly raised above and beneath, secondary veins 13–15 pairs, higher order veins reticulate. Staminate inflorescences terminal and axillary on apical nodes, several close together, thyrsoid to slightly paniculate with short side branches, to 11.3 cm long, angular to flattened, hairy, quickly glabrescent; bracts ovate, 2.7–4 by 1.7–3 mm to elliptic, c. 5 by 1 mm, outside usually hairy, inside glabrous. Staminate flowers c. 8 mm diam, white, unpleasant smell; pedicel 4.5–5.5 mm long above abscission zone, round to slightly flattened, with few hairs, abscission zone well-visible, not hidden by bracts; calyx 3–3.3 mm high, lobes ovate, 1.7–2.3 by 2–2.5 mm, thickest in middle, thinnest at margins, margin and often base outside hairy, apex emarginate to rounded; petals ovate to obovate, 4.2–5.5 by 3.3–6 mm, apex rounded, few hairs outside; disc glands rectangular (not zig-zagging around stamens), 0.3–1 by 0.3–0.8 mm, thick, apex hairy; stamens 11–12, 5 outer free or base adnate to androphore, filaments c. 4.5 mm long, central 6–7 partly united in an androphore of c. 4 mm long, free part of filaments c. 1.5 mm, anther elliptic, 0.6–1 by 0.8–1 mm. Pistillate flowers, fruits and seeds unknown.

Distribution — Endemic in the N Moluccas (Bacan, Halmahera).

Habitat & Ecology — Rather dense primary forest to secondary forest on deep clayey soil. Altitude: sea level to 15 m. Flowering: August, September.