Iguanura australis (Beccari) Henderson

Henderson, Andrew, 2025, A revision of Iguanura (Arecaceae, Arecoideae, Areceae), Phytotaxa 690 (2), pp. 135-188 : 146-147

1. Iguanura australis (Beccari) Henderson , comb. & stat. nov. Iguanura borneensis var. australis Beccari (1934: 172) . Type:— INDONESIA. S.-O. Borneo, 1908, H. Winkler 2782 (holotype FI-014159!, isotype L-1407296!).

Stems length not recorded, 1.0(0.8–1.3) cm diameter, branching not recorded. Leaf sheaths 12.4(10.7–14.0) 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 length not recorded; rachises 35.5 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 per side of rachis; middle pinna 18.3(16.5–20.0) cm long, 5.2(5.0–5.4) cm wide. Inflorescences branched to 1 order; prophylls and peduncular bracts inserted some distance apart, more or less persistent; peduncles length not recorded, not wooly tomentose; rachises 3.7 cm long; rachillae 5, 9.5 cm long, 1.8(1.5–2.1) mm diameter, widely diverging from the rachis, proximal part of rachillae not with distantly spaced triads, densely tomentose, not filiform with triads sunken in shallow, more or less closely spaced pits; rachilla bracts elongate, acuminate, densely tomentose at apex; distal triad bracteoles well-developed; distal part of flower pits glabrous; staminate flowers 4.0–5.0 mm long with pointed apices; anther margins undulate; fruits 8.1 mm long, 6.3 mm diameter, ellipsoid, ridged, the surfaces drying pebbled, color not recorded; endocarp circular in cross-section; endosperm homogeneous.

Distribution and habitat:— Indonesia (East and South Kalimantan), habitat not recorded, at 30 m elevation ( Fig. 7 ).

Taxonomic notes: — Iguanura australis is recognized as a phylogenetic species—see notes under I. borneensis . It is characterized by its diverging leaf veins and elongate, acuminate rachilla bracts that are densely tomentose at the apices.

Kiew (1976) described I. australis (under I. borneensis ) as having “distinctly trapezoid segments”, and the two specimens (Winkler 2782, Kostermans 6479) are here scored as having diverging venation. These are the only two specimens and are from widely separate localities, an unusual situation in Iguanura . The type specimen (Winkler 2782) is from southeastern Borneo and the second (Kostermans 6479) from eastern Borneo, about 400 km away.

Figures

FIGURE 7. Distribution of Iguanura australis, I. beccarii, I. bicornis, and I. borneensis.