Iguanura parvula Beccari

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

24. Iguanura parvula Beccari in Hooker (1892: 417). Lectotype (designated by Saw 2023):— MALAYSIA. District of Perak in the Malay Peninsula , no date, B. Scortechini s.n. (lectotype FI-014156!).

Iguanura speciosa Hodel (1997a: 29) . Iguanura polymorpha var. integra Lim (1998b: 112) . Type:— THAILAND. SW of Narathiwat, 600 m, 18 February 1997, D. Hodel & P. & R. Vatcharakorn 1628 (holotype BK n.v., isotype BH!).

Stems 0.3 m long, 0.7(0.5–1.1) cm diameter, solitary or clustered. Leaf sheaths 7.8(5.0–14.5) 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 8.9(4.0–18.0) cm long; rachises 25.1(18.5–38.0) cm long; leaf blades undivided or rarely divided, not rounded at the apex, with a deep split; leaf veins parallel; adaxial leaf veins not prominent adaxially, triangular in cross-section; pinnae 1–3 per side of rachis; middle pinna 11.5 cm long, 4.9 cm wide. Inflorescences branched to 1 order; prophylls and peduncular bracts inserted some distance apart, more or less persistent; peduncles 8.9(5.8–12.3) cm long, not wooly tomentose; rachises 1.5(0.0–4.0) cm long; rachillae 4(2–6), 7.5(4.2–10.0) cm long, 1.4(0.8–2.3) 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; staminate flowers 2.0– 2.5 mm long with blunt apices; anther margins not undulate; fruits not recorded.

Distribution and habitat:—Southeastern Peninsular Thailand and northwestern Peninsular Malaysia in hill forest or primary tropical rainforest at 396(67–790) m elevation (Fig. 13).

Taxonomic notes:— Preliminary species Iguanura parvula was polymorphic for three variables (stem branching, leaf division, rachillae tomentum). These were treated as traits, and then I. parvula had a unique combination of qualitative character states and is recognized as a phylogenetic species. It is characterized by its parallel leaf venation and leaf veins that are not prominent adaxially. However, recognition of I. parvula as a phylogenetic species is somewhat problematic. All but one specimen (Damahuri FRI 36713) have undivided leaves. One specimen ( Wan Syafiq FRI 90233) of I. polymorpha is remarkably similar to I. parvula , and has both divided and undivided leaves. It was included in I. parvula by Saw (2023).

Iguanura parvula occurs in two, separate populations, here recognized as morphotypes.

Subspecific variation:— The parvula morphotype (based on I. parvula ) occurs in northwestern Peninsular Malaysia, in Perak. It has small, usually undivided, oblong-shaped leaves and inflorescences with few, short rachillae. One specimen (Damahuri FRI 36713) from a slightly different area than the others, has divided leaves, with three pinnae per side of the rachis.

The speciosa morphotype (based on I. speciosa ) occurs in southeastern Peninsular Thailand, about 125 km from the parvula locality. It is like the parvula morphotype in its small, undivided, oblong-shaped leaves and inflorescences with few, short rachillae, but it has slightly larger leaves and fewer rachillae (2–3 versus 4–6).