Iguanura curvata Kiew (1979: 143)

Henderson, Andrew, 2025, A revision of Iguanura (Arecaceae, Arecoideae, Areceae), Phytotaxa 690 (2), pp. 135-188 : 154-155

8. Iguanura curvata Kiew (1979: 143) . Type:— MALAYSIA. Sarawak, Ulu Temalad, Mujong, Balleh, c. 900 m, 22 March 1964, P. Ashton S.17623 (holotype K-000697877!, isotype SAR!).

Stems 1.2(0.4–2.0) m long, 1.1(0.7–1.4) cm diameter, clustered. Leaf sheaths 11.3(7.0–15.0) 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 21.6(6.8–41.0) cm long; rachises 33.9(19.0–42.0) cm long; leaf blades divided, not rounded at the apex, with a deep split; leaf veins diverging; adaxial leaf veins prominent, rectangular in cross-section; pinnae 3(2–5) per side of rachis; middle pinna 18.7(12.5–28.0) cm long, 5.0(2.9–7.4) cm wide. Inflorescences branched to 1 or 2 orders; prophylls and peduncular bracts inserted some distance apart, more or less persistent; peduncles 12.5 cm long, not wooly tomentose; rachises 3.5(0.0–7.5) cm long; rachillae 6(2–12), 15.4(8.0–34.0) cm long, 1.5(0.9–2.2) mm diameter, widely diverging from the rachis, proximal part of rachillae not with 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 2.0– 2.5 mm long with blunt apices; anther margins undulate; fruits 16.7(16.0–17.4) mm long, 6.0(4.9–7.2) mm diameter, narrowly ovoid, curved, sometimes curved over at apex, ridged, the surfaces drying smooth, red or white; endocarp circular in cross-section; endosperm homogeneous.

Distribution and habitat:— Malaysia ( Sarawak, Sabah) in mixed Dipterocarp forest or alluvial forest at 508(55– 900) m elevation ( Fig. 8 ).

Taxonomic notes:— Preliminary species Iguanura curvata was polymorphic for 10 variables (stem branching, sheaths, sheath indumentum, ocreas, leaf venation, orders of inflorescence branching, rachillae tomentum, pit tomentum, fruit surfaces, endocarp shape). Four of these were treated as traits, and the other six (sheaths, sheath indumentum, ocreas, leaf venation, fruit surfaces, endocarp shape) were used to split preliminary species I. curvata into three phylogenetic species, I. curvata , I. lunata , and I. grandis . Iguanura curvata is characterized by its well-developed ocreas and narrowly ovoid, curved, ridged fruits.

Two specimens (Abg. Mokhtar S.44728, S. Lai S.74135) were excluded. They are from within the range of I. curvata , but have densely indumentose leaf sheaths. They lack fruits and remain unidentified.

Subspecific variation:— Iguanura curvata is widespread and unusually variable. At one extreme is a specimen (Purseglove P.5278) that has small leaves with only two pinnae per side of the 19.0 cm long rachis, and inflorescences with two rachillae that are relatively short (the SING duplicate has only one rachilla). This specimen was determined by Kiew (1976) as I. polymorpha . At the other extreme, a specimen (P. Ashton S.17623) has large leaves with four pinnae per side of the 42.0 cm long rachis, and four, 34.0 cm long rachillae. However, the curved fruits appear quite uniform in all specimens, with three prominent ridges on the dorsal side.

Figures

FIGURE 8. Distribution of Iguanura brevipes, I. bruneiensis, I. chaiana, and I. curvata.