Iguanura palmuncula Beccari (1886: 106)

Henderson, Andrew, 2025, A revision of Iguanura (Arecaceae, Arecoideae, Areceae), Phytotaxa 690 (2), pp. 135-188 : 171-173

23. Iguanura palmuncula Beccari (1886: 106) . Type:— MALAYSIA. Borneo, Sarawak, Mte. Matang, November

1867, O. Beccari 3957 (FI-008393!).

Iguanura palmuncula Beccari var. angustisecta Beccari (1886: 107) . Lectotype (designated here):— MALAYSIA. Mte. Matang, November 1867, O. Beccari 3957 (FI-008394!).

Iguanura ambigua Beccari (1886: 105) . Type:— MALAYSIA. Borneo, Sarawak, Matang, January 1866, O. Beccari 1308 (holotype FI-008389!).

Stems 0.4(0.1–1.0) m long, 1.3(1.0–1.8) cm diameter, solitary or clustered. Leaf sheaths 9.8(4.0–14.0) cm long, open and more or less persistent, not cleanly falling, initially covered with dense, woolly indumentum; ocreas scarcely developed; petioles 21.2(6.5–42.0) cm long; rachises 44.4(23.0–58.5) 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 4(1–6) per side of rachis; middle pinna 29.2(14.5–38.0) cm long, 3.3(1.4–4.6) cm wide. Inflorescences spicate or branched to 1 order; prophylls and peduncular bracts inserted some distance apart, more or less persistent; peduncles 26.3(8.5–41.4) cm long, densely reddish-brown, wooly tomentose; rachises 0.9(0.0–5.7) cm long; rachillae 2(1–6), 17.5(7.5–25.5) cm long, 1.9(1.0–2.8) 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 glabrous; staminate flowers 2.0– 2.5 mm long with blunt apices; anther margins undulate; fruits 12.9(11.5–15.7) mm long, 6.2(5.1–8.7) mm diameter, oblong, apiculate, ridged, the surfaces drying smooth, red, rose pink, pinkish-white, or white flushed pink; endocarp polygonal in cross-section; endosperm homogeneous.

Distribution and habitat:— Malaysia ( Sarawak) in upper hill Dipterocarp forest, riparian forest, submontane forest, or montane forest on Gunung Serapi (Mount Matang) at 668(500–750) m elevation (Fig. 13).

FIGURE 13. Distribution of Iguanura palmuncula , I. parvula , I. polymorpha , and I. remotiflora .

Taxonomic notes:— Preliminary species Iguanura palmuncula was polymorphic for 12 variables (stem branching, sheaths, sheath indumentum, ocreas, leaf division, orders of inflorescence branching, rachillae tomentum, rachillae diameter, pit tomentum, fruit shape, fruit surfaces, endocarp). Five of these were treated as traits, and the other seven (sheaths, sheath indumentum, ocreas, rachillae diameter, fruit shape, fruit surfaces, endocarp) were used to split preliminary species I. palmuncula into four phylogenetic species, I. palmuncula , I. magna , I. montana , and I. tomentosa . Iguanura palmuncula is characterized by its sheaths initially covered with dense, woolly indumentum, scarcely developed ocreas, and non-filiform rachillae. Another preliminary species, I. ambigua , had the same combination of character states as I. palmuncula and is included here.

Kiew (1976) cited four specimens of I. ambigua , the type (Beccari 1308) and three others (Hewitt 35, Ridley 1903, 11816). All are from Mount Matang, with the possible exception of Hewitt 35, which lacks locality data (although Hewitt is known to have collected on Mount Matang ( van Steenis 1950)). Kiew wrote that none of these specimens had ripe fruits, although Ridley 11816 was said to have immature fruits with “the dorsal ridge somewhat extended”. However, the K duplicate of Hewitt 35 has mature fruits and these are typically oblong apiculate. Kiew illustrated I. ambigua as having ovoid fruits (her Fig. 3a ) but it is unclear whose collection this is (although it is probably the immature fruits of Ridley 11816).

The type of I. palmuncula var. angustisecta is exactly like other specimens of I. palmuncula , and this is included here.

Kiew (1976) reported that I. wallichiana subsp. malaccensis var. malaccensis occurred on Mount Matang, based on J. Dransfield 768. However, this appears to be an error, and the KEP duplicate of this specimen is here determined as I. palmuncula .

Subspecific variation:— Two specimens have undivided leaves, the type of Iguanura ambigua and one other; all others have divided leaves. Iguanura palmuncula is scored as having rachillae that are not filiform, with the triads sunken in shallow, more or less closely spaced pits. However, several specimens are difficult to score, and there is considerable range in the thickness of rachillae. One specimen, Hewitt 35, has two inflorescences, one spicate with relatively thin rachillae and one with two, much thicker rachillae.

Figures

FIGURE 3. A. Leaf blade divided, not rounded at the apex, with a deep apical split; leaf veins diverging, adaxial veins not prominent, triangular in cross-section (I. polymorpha). B. Inflorescence spicate (I. geonomiformis). C. Inflorescence branched to 1 order; rachillae not diverging from rachis, the proximal, adaxial rachilla surfaces flat, lying close to the flat rachis surface; proximal part of rachillae with markedly distantly spaced triads (I. geonomiformis, Saw Leng Guan FRI 37594). D. Inflorescence branched to 1 order; rachillae widely diverging from the rachis; proximal part of rachillae not with distantly spaced triads (I. wallichiana K. Larsen 44159).