Iguanura melinauensis Kiew (1976: 208)

Henderson, Andrew, 2025, A revision of Iguanura (Arecaceae, Arecoideae, Areceae), Phytotaxa 690 (2), pp. 135-188 : 166

17. Iguanura melinauensis Kiew (1976: 208) . Type:— MALAYSIA. Sarawak, Baram District, Melinau Gorge, 4˚10’N 114˚55’E, below 1,000 ft., 27 June 1962, Chew Wee-Lek 487 (holotype SING-0072413!, isotypes K-000207982!, L-1407263!, SAR!).

Stems 1.5 m long, 0.9(0.7–1.3) cm diameter, solitary or clustered. Leaf sheaths 11.8(7.5–14.0) cm long, tubular, mostly closed opposite the petiole, cleanly falling, covered with a thin layer of indumentum; ocreas well-developed, separating early into fibers and disintegrating; petioles 11.4(4.5–16.0) cm long; rachises 35.0(24.0–58.5) cm long; leaf blades divided, less often undivided, not rounded at the apex, with a deep split; leaf veins parallel; adaxial leaf veins prominent, rectangular in cross-section; pinnae 2(1–4) per side of rachis; middle pinna 22.4(13.7–26.0) cm long, 5.6(3.6–8.5) cm wide. Inflorescences branched to 1 order; prophylls and peduncular bracts inserted some distance apart, more or less persistent; peduncles 31.0(26.0–36.0) cm long, not wooly tomentose; rachises 3.7(1.7–6.0) cm long; rachillae 5(4–7), 13.8(10.0–18.0) cm long, 0.9(0.5–1.3) mm diameter, widely diverging from the rachis, proximal part of rachillae not with distantly spaced triads, glabrous or sparsely tomentose, filiform with superficial, distantly spaced triads; rachilla bracts not elongate; distal triad bracteoles well-developed; distal part of flower pits glabrous; staminate flowers 2.0– 2.5 mm long with blunt apices; anther margins undulate; fruits 10.6(9.1–12.8) mm long, 6.5(5.7–7.0) mm diameter, ellipsoid, ridged, the surfaces drying smooth, white or pinkish-red; endocarp polygonal in cross-section; endosperm homogeneous.

Distribution and habitat:— Malaysia ( Sarawak) in forest on limestone, limestone scree, alluvial forest, or transition from kerangas to alluvial forest, at 89(30–150) m elevation (Fig. 11).

Taxonomic notes:— Preliminary species Iguanura melinauensis was polymorphic for two variables (stem branching, leaf division). These were treated as traits, and then it had a unique combination of character states and is recognized as a phylogenetic species. It is characterized by its tubular, mostly closed sheaths, well-developed ocreas, proximal part of rachillae not with distantly spaced triads, filiform rachillae, and ellipsoid fruits.

The leaves are notable in having the distalmost pinna much wider than the others, and a few specimens have undivided leaves. The K duplicate of one specimen (J. Anderson S.31831) has inflorescences with five rachillae, and is so scored. However, another duplicate at L has spicate inflorescences.