Iguanura macrostachya Beccari (1886: 101)

Henderson, Andrew, 2025, A revision of Iguanura (Arecaceae, Arecoideae, Areceae), Phytotaxa 690 (2), pp. 135-188 : 163-165

15. Iguanura macrostachya Beccari (1886: 101) . Type:— MALAYSIA. Borneo, Sarawak, Colline del Sakarran,

October 1867, O. Beccari 3851 (FI-008391!).

Iguanura prolifera Kiew (1976: 214) . Type:— INDONESIA. Borneo, G. Kenepai, 1894-1894, H. Hallier 1759 (holotype L-0042124!, L-0042125!).

Stems 0.9(0.2–2.0) m long, 1.7(1.0–3.0) cm diameter, solitary or clustered. Leaf sheaths 14.3(12.0–15.0) cm long, open and more or less persistent, not cleanly falling, covered with a thin layer of indumentum; ocreas well-developed, separating early into fibers and disintegrating; petioles 21.1(7.0–35.0) cm long; rachises 51.0(36.7–65.0) cm long; leaf blades divided, not rounded at the apex, with a deep split; leaf veins parallel; adaxial leaf veins prominent, rectangular in cross-section; pinnae 5(3–11) per side of rachis; middle pinna 22.0(15.5–26.0) cm long, 4.0(1.8–5.5) cm wide. Inflorescences spicate or branched to 1 order; prophylls and peduncular bracts inserted some distance apart, more or less persistent; peduncles 59.3(50.0–68.5) cm long, not wooly tomentose; rachises 0.0 cm long; rachillae 1–2, 40.4(30.0–60.5) cm long, 2.5(1.7–3.3) mm diameter, proximal part of rachillae with markedly distantly spaced triads, glabrous or sparsely to densely tomentose, not filiform with triads sunken in shallow, more or less closely spaced pits; rachilla bracts not elongate; distal triad bracteoles well-developed; distal part of flower pits densely tomentose or glabrous; staminate flowers 4.0–5.0 mm long with pointed apices; anther margins undulate; fruits 10.5(9.0–13.0) mm long, 5.9(5.1–6.6) mm diameter, ellipsoid, ridged, the surfaces drying pebbled, pink, powder pink, light red, red, or reddish; endocarp polygonal in cross-section; endosperm homogeneous.

Distribution and habitat:— Malaysia ( Sarawak) and Indonesia (West, Central, East, and South Kalimantan) in hill, lowland, or mixed Dipterocarp forest, or riverside forest on alluvial flats at 179(20–1,200) m elevation (Fig. 11). There is a single record from Sarawak, the type, collected by Beccari in 1867 on the ‘Colline del Sakarran’. Based on Beccari (1986) this locality is likely to be near the headwaters of the Sekarang River, where it is here mapped.

Taxonomic notes:— Preliminary species Iguanura macrostachya was polymorphic for nine variables (stem branching, sheaths, sheath indumentum, leaf division, orders of inflorescence branching, rachillae tomentum, pit tomentum, staminate flowers, fruit surfaces). Five of these were treated as traits and the other four (sheaths, sheath indumentum, staminate flowers, fruit surfaces) were used to split preliminary species I. macrostachya into three phylogenetic species, I. macrostachya , I. beccarii , and I. exilis . Iguanura macrostachya is characterized by its open and more or less persistent sheaths that are covered with a thin layer of indumentum, and endocarp polygonal in cross-section. Another preliminary species, I. prolifera , had the same combination of character states as I. macrostachya and is included here.

PLATE 6 . Holotype of Iguanura lunata .

Anther margins are scored as undulate. However, in bud the anthers appear non-undulate, it is only when the anthers dehisce that the margins appear undulate. Kiew (1976) cited two specimens of I. prolifera , the type and Meijer 503. She stated that the anthers were not undulate. Staminate flowers from these specimens have not been examined, but those of other specimens (A. Kostermans 10481, E. de Vogel 2184) have undulate anthers. One specimen (J. Dransfield 1596) has a bifurcate inflorescence, all others are spicate. One specimen (J. Mogea 3872) comes from an unusually high elevation, 1,200 m.

FIGURE 11. Distribution of Iguanura macrostachya , I. magna , I. melinauensis , and I. minor .