Iguanura elegans Beccari (1886: 103)

Henderson, Andrew, 2025, A revision of Iguanura (Arecaceae, Arecoideae, Areceae), Phytotaxa 690 (2), pp. 135-188 : 155-157

9. Iguanura elegans Beccari (1886: 103) . Lectotype (designated here):— MALAYSIA. Borneo, Sarawak, Kuching ,

July 1865, O. Beccari 163 (lectotype FI-008390!, FI-014151!, isolectotypes K-000207983!, K-000207984!, K-

000207985!, SING-0249887!). Plate 2.

Iguanura sanderiana Ridley (1904b: 50) . Type:— MALAYSIA. Sarawak, Lundu River, no date, W. Micholitz 11849 (holotype K-000208069!, K-000207979!, isotype SING-0249898!).

Iguanura ridleyana Beccari (1934: 173) . Type:— MALAYSIA. Sarawak, Jambusan, September 1905, H. Ridley 12399 (holotype K!, isotype SING-0249894!).

Stems 0.8(0.1–1.5) m long, 1.2(0.7–1.9) cm diameter, solitary or clustered. Leaf sheaths 10.8(8.0–17.0) 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 9.1(4.5–20.0) cm long; rachises 48.1(33.0–64.5) cm long; leaf blades undivided, less often divided, rounded at the apex, with a shallow or absent split; leaf veins parallel; adaxial leaf veins prominent, rectangular in cross-section; pinnae 1–4 per side of rachis; middle pinna 32.8(28.5–37.0) cm long, 6.6(2.4–10.7) cm wide. Inflorescences spicate or branched to 1 order; prophylls and peduncular bracts inserted some distance apart, more or less persistent; peduncles 25.5(20.5–29.5) cm long, not wooly tomentose; rachises 1.4(0.0– 6.7) cm long; rachillae 2(1–5), 16.9(8.7–27.0) cm long, 2.4(0.8–4.2) 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 4.0–5.0 mm long with pointed apices; anther margins undulate; fruits 10.0(9.0–11.0) mm long, 6.5(5.8–6.9) mm diameter, ellipsoid, ridged, the surfaces drying pebbled, white, pink, pinkish, red, reddish, bright red, dark red, or orange; endocarp circular in cross-section; endosperm homogeneous.

Distribution and habitat:— Malaysia (western Sarawak) in kerangas forest, limestone forest, peat swamp forest, lowland rainforest, mixed Dipterocarp forest, or primary forest at 72(20–160) m elevation ( Fig. 9 ).

Taxonomic notes:— Preliminary species Iguanura elegans was polymorphic for 11 variables (stem branching, sheaths, ocreas, leaf division, leaf shape, orders of inflorescence branching, rachillae divergence, proximal triad spacing, rachillae tomentum, pit tomentum, staminate flowers). Much of this polymorphism was from a group of nine specimens that are here considered to be hybrids, as discussed below. Excluding these specimens, preliminary species I. elegans was polymorphic for five variables (stem branching, leaf division, orders of inflorescences branching, rachillae tomentum, pit tomentum). These were treated as traits, and then preliminary species I. elegans had a unique combination of qualitative character states and is recognized as a phylogenetic species. Another preliminary species I. sanderiana had the same combination of character states and is included here. Iguanura elegans is characterized by its leaf blades that are rounded at the apex with a shallow or absent apical split.

Kiew (1976) reported that staminate flowers of I. sanderiana were 2.0 mm long, but those of the type specimen are 3.9 mm long and are scored as long. Another specimen ( Yii Puan Ching Sk. 45951) also has long staminate flowers. Kiew (1976) included I. ridleyana as a synonym of I. elegans , and this is followed here.

Subspecific variation:—There is considerable, confusing variation in this species, particularly in leaf shape and the depth of the apical split, and orders of inflorescence branching. Without fruits, specimens of I. elegans with spicate inflorescences are difficult to distinguish from specimens of I. beccarii with undivided leaves. Iguanura elegans has a more northerly distribution in western Sarawak, and I. beccarii a more southerly one. The two species overlap in the Jambusan region, and here there appear to be hybrids between the two.

Some specimens (e.g., Rena George S.38297, Sie S.43890) of I. elegans have leaves with a relatively deep apical split ( Plate 2), and some (e.g., Julaihi S.74703) have spicate inflorescences, like I. beccarii . Similarly, some specimens (Dransfield 5888, Jugah S.67493, Lee S.38621, Meekiong SBC 1966, Othman S.37456, Patsipun S.79913, Rantai Jawa S.70022, Yii Puan Ching 50310) of I. beccarii with undivided leaves approach those of I. elegans in shape, and two of these (Meekiong SBC 1966, Othman S.37456) have branched inflorescences. These specimens are all from the Jambusan region, an area with numerous limestone outcrops, and may be hybrids between the two species.

A few other specimens are problematic. Three specimens (KP 32/19, Kuteh 97/38, Ridley s.n.) resemble I. elegans in their leaves but appear to have short staminate flowers. Four specimens (G. Connie SBC 2813, Patsipun S.79981, Ridley 11814, 0249885), one of which was determined as I. elegans by Kiew (1976), have divided leaves unlike those of I. elegans , one with a deep apical split. These are also from the Jambusan region and appear be hybrids with I. beccarii .

Kiew (1976) determined two specimens (Brunig 31, 34) from Bako National Park as I. sanderiana . They have considerably larger leaves than other specimens of I. elegans , with the rachis up to 100 cm long, with a distinct apical split and large inflorescences. Brunig 31 has a spicate inflorescence with a 45 cm long rachilla. They lack staminate flowers and fruits and remain unidentified, but it seems likely they represent an undescribed species. There is a more typical-sized specimen (Brunig 4) of I. elegans from the same area.

Figures

FIGURE 9. Distribution of Iguanura elegans, I. exilis, I. grandis, and I. lunata.