Iguanura tenuis Hodel (1997b: 11)

Henderson, Andrew, 2025, A revision of Iguanura (Arecaceae, Arecoideae, Areceae), Phytotaxa 690 (2), pp. 135-188 : 179

28. Iguanura tenuis Hodel (1997b: 11) . Type:— THAILAND. Between Takuapa and Phanom, 600 m, no date, D.

Hodel & P. & R. Vatcharakorn 1727 (holotype BK n.v.). Plate 9.

Iguanura tenuis var. khaosokensis Lim (1998b: 112) . Type:— THAILAND. Surat Thani, Khao Sok, 1997, Lim Chong Keat H 1993 (holotype BKF n.v., isotype KEP n.v.) According to Saw (2023) the specimens were not distributed to these herbaria.

Stems 1.0 m long, 0.8(0.7–0.9) cm diameter, solitary. Leaf sheaths 7.0(6.5–7.5) cm long, swollen, mostly open opposite the petiole, cleanly falling, covered with a thin layer of indumentum; ocreas well-developed, separating early into fibers and disintegrating; petioles 4.3(2.5–6.0) cm long; rachises 38.9(25.0–52.0) cm long; leaf blades divided, not rounded at the apex, with a deep split; leaf veins diverging; adaxial leaf veins not prominent triangular in cross-section; pinnae 5(4–6) per side of rachis; middle pinna 19.2(15.7–25.0) cm long, 4.5(3.0–6.0) cm wide. Inflorescences branched to 1 or 2 orders; prophylls and peduncular bracts inserted some distance apart, more or less persistent; peduncles length not recorded, not wooly tomentose; rachises 4.3(0.0–11.2) cm long; rachillae 5(2–7), 17.0(9.5–25.0) cm long, 1.0(0.8–1.2) mm diameter, widely diverging from the rachis, proximal part of rachillae not with distantly spaced triads, glabrous or sparsely tomentose, filiform with superficial, distantly spaced triads; 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 not undulate; fruits 11.2 mm long, 6.2 mm diameter, ellipsoid, not ridged, the surfaces drying pebbled, pinkish; endocarp circular in cross-section; endosperm homogeneous.

Distribution and habitat:— Western Peninsular Thailand in primary, wet, evergreen forest, hill Dipterocarp forest, or evergreen, gallery forest at 320(100–900) m elevation (Fig. 14).

Taxonomic notes:— Iguanura tenuis is recognized as a phylogenetic species — see notes under I. brevipes . It is characterized by its swollen leaf sheaths and filiform rachillae.

Hodel (1997b) considered I. tenuis to be similar to I. polymorpha , differing in its leaf sheaths. He described sheaths as being “tubular, persistent, marcescent, not forming a crownshaft.” Although the type specimen has not been seen, there are several specimens from at or near the type locality. From these it can be seen that the leaf sheaths are swollen, mostly open opposite the petiole, and cleanly falling. Lim (1998b) described a new variety of I. tenuis, var. khaosokensis , based on its solitary (versus clustered) stems. This difference is not considered here to have any taxonomic significance. Iguanura tenuis was included by Saw (2023) as a synonym of I. divergens .