Iguanura wallichiana (Martius) Bentham & Hooker ex Beccari (1886: 100)

Henderson, Andrew, 2025, A revision of Iguanura (Arecaceae, Arecoideae, Areceae), Phytotaxa 690 (2), pp. 135-188 : 180-183

31. Iguanura wallichiana (Martius) Bentham & Hooker ex Beccari (1886: 100) . Areca wallichiana Martius (1838:

178). Iguanura wallichiana subsp. wallichiana var. wallichiana (Martius) Kiew (1976: 221) . Lectotype (designated by

Saw 2023):— MALAYSIA. Penang, no date, G. Porter 8600 (holotype K-000207987!). Plate 9.

Iguanura wallichiana var. major Beccari ex Hooker (1892: 416) . Geonoma pynaertiana Sander (1898: 258) . Iguanura wallichiana subsp. wallichiana var. major (Beccari ex Hooker) Kiew (1976: 221) . Iguanura spectabilis Ridley (1904a: 40) nom. superfl. Lectotype (designated by Saw 2023):— MALAYSIA. Perak, nr. Bruas, February 1897, H. Ridley 8403 (lectotype SING-0151719!, SING-0151720!, isolectotype K-000208054!).

Iguanura wallichiana var. minor Beccari ex Hooker (1892: 416) . Lectotype (designated by Saw 2023):— MALAYSIA. Goping, August 1880, Dr. King’s collector 454 (holotype FI-014146!).

Iguanura diffusa Beccari in Hooker (1892: 416). Lectotype (designated by Saw 2023):— MALAYSIA. District of Perak in the Malay Peninsula, G. Tjok, August 1884, B. Scortechini 1181 (lectotype FI-014155!).

Iguanura multifida Hodel (1997b: 8) . Type:— THAILAND. Betong, 800 m, no date, D. Hodel & P. & R. Vatcharakorn 1745 (holotype BK n.v.).

Iguanura wallichiana var. rosea Lim (1998 a: 23) . Type:— MALAYSIA. Perak, Belukar Semang, 1992, C. K. Lim H 1126 (holotype KEP-171509!, KEP-171510!, KEP-21540!).

Iguanura asli Lim (1998 a: 28) . Type:— MALAYSIA. Pahang, Berkelah F.R., 20 September 1993, C. K. Lim H 1539 (holotype SING-0072412!).

Iguanura piahensis Lim (1998 a: 31) . Type:— MALAYSIA. Perak, Grik, Sungai Piah F. R., 100 m, 1992, C. K. Lim PSM 1266 (holotype KEP-21644!, KEP-169958!, KEP-169959!, KEP-169960!, KEP-169961!, KEP-169962!, KEP-169963!, KEP-169964!, KEP-169965!).

Iguanura perdana Lim (1998 a: 55) . Type:— MALAYSIA. Perak, Kroh, 1992, C. K. Lim H 1125 (holotype KEP-169968!, KEP-169969!, KEP-169970!, KEP-21643!).

Iguanura cemurung Lim (2003: 147) . Type:— MALAYSIA. Terengganu, Hutan Lipur Cemurung, 2003, C. K. Lim L 6506 (holotype KEP n.v., isotypes K n.v., SING n.v.). According to Saw (2023) the specimens were not distributed to these herbaria.

PLATE 11 . Holotype of Iguanura tomentosa .

Stems 1.4(0.4–3.0) m long, 1.7(0.9–2.6) cm diameter, solitary or clustered. Leaf sheaths 17.0(9.5–31.0) 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 25.2(2.5–150.0) cm long; rachises 68.6(32.0–160.0) cm long; leaf blades undivided or divided, not rounded at the apex, with a deep split; leaf veins parallel; adaxial leaf veins prominent adaxially and rectangular in cross-section, rarely not prominent, triangular in cross-section; pinnae 5(1–20) per side of rachis; middle pinna 33.8(20.5–49.0) cm long, 4.9(0.7–9.5) cm wide. Inflorescences branched to 1 or 2 orders; prophylls and peduncular bracts inserted some distance apart, more or less persistent; peduncles 33.8(8.0–96.5) cm long, not wooly tomentose; rachises 6.1(0.0–21.2) cm long; rachillae 7(2–17), 20.0(7.5–43.0) cm long, 2.0(0.9–3.6) 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 2.0– 2.5 mm long with blunt apices; anther margins not undulate; fruits 12.1(7.7–16.9) mm long, 8.0(6.2–11.2) mm diameter, ellipsoid, not ridged, the surfaces drying pebbled, cream, white, light yellow, yellowish, pink, red, or purplish-red; endocarp circular in cross-section; endosperm ruminate, rarely homogeneous.

Distribution and habitat:—Peninsular Thailand, Peninsular Malaysia, and Sumatra in lowland Dipterocarp forest, hill forest, swamp forest, or wet forest at 313(38–1,265) m elevation (Fig. 15). Kiew (1976) considered I. wallichiana to be present in Borneo, based on Dransfield 768 from Sarawak. This specimen is here determined as I. palmuncula , and I. wallichiana does not occur in Borneo.

Taxonomic notes:— Preliminary species Iguanura wallichiana was polymorphic for eight variables (stem branching, leaf division, adaxial veins, orders of inflorescence branching, rachillae tomentum, distal bracteole, pit tomentum, and endosperm). These were treated as traits (see discussion below). Then preliminary species Iguanura wallichiana had a unique combination of character states and is recognized as a phylogenetic species. It is characterized by its rachillae diverging from rachis, and the proximal part of rachillae without markedly distantly spaced triads. Two other preliminary species, I. asli and I. cemurung , had the same combination of character states and are included.

Iguanura walllichiana is closely related to I. geonomiformis (see notes under that species), and both are widespread and variable. Both appear to be classic examples of ochlospecies. Some of the more obvious morphotypes are discussed here, although there appear to be several others.

Subspecific variation:—The wallichiana morphotype (based on I. wallichiana , I. wallichiana var. minor , I. wallichiana var. rosea ) occurs in the southern part of Peninsular Thailand (Plate 9) and continues into the northwestern and central-western part of Peninsular Malaysia and Sumatra. It has undivided or divided leaves and inflorescences with several rachillae. The rachillae tend to be relatively thin and less tomentose. There are a few aberrant specimens from scattered localities. These were determined by Saw (2023) as I. geonomiformis but are here considered to be I. wallichiana , although their inflorescences are admittedly difficult to score (and may be a result of the way the specimens were pressed). Some of these are from areas of overlap between I. geonomiformis and I. wallichiana and are possible hybrids.

In the northwestern part of Peninsular Malaysia there is a distinctive morphotype with large, usually undivided leaves, the major morphotype (based on I. wallichiana subsp. wallichiana var. major ).

Although the wallichiana morphotype usually has undivided leaves or blades divided into a few pinnae, in a few localities, both in Peninsular Thailand and Peninsular Malaysia, specimens have leaf blades divided into numerous (up to 20), narrow pinnae. These forms have been described as I. diffusa and I. multifida and are here referred to as the diffusa morphotype. These forms appear to have arisen independently in different places.

The asli morphotype is based on I. asli and I. cemurung . For unknown reasons, I. cemurung was listed as an accepted species by POWO (2024) despite Saw (2023) having included it as a synonym of I. asli . The asli morphotype occurs on the eastern side of southern Peninsular Malaysia. It has inflorescences with short peduncles but otherwise is similar to the wallichiana morphotype. Seeds of some specimens appear to have scarcely ruminate endosperm.

There are five specimens (Saw Leng Guan FRI 44361, FRI 44367, T. Whitmore FRI 3808, Meijer 94916, J. Dransfield 4553) that are problematic. They are all from the same locality, near Kuantan in Pahang State. They were annotated by Dr. Saw Leng Guan as a new species, I. kuantanensis , but later determined as I. asli ( Saw 2023) . However, they appear to have diverging pinnae venation, and two have ellipsoid fruits with homogeneous endosperm. They are quite variable in leaf morphology, with one specimen having three pinnae per side of the rachis, and another 11. They do not appear to be hybrids because they are the only species at that locality. They remain unidentified.

Lim (1998 a) described I. piahensis as close to I. wallichiana but differing in its thin leaf blade with a “silky glabrous sheen”. Saw (2023) included it as a synonym of I. wallichiana . Here it is scored as having the adaxial leaf veins not prominent and triangular in cross-section, and thus different from other specimens of I. wallichiana . Leaf shape is remarkably similar to that of I. parvula , although the distribution of the two species does not overlap. It seems possible that the two specimens of I. piahensis are hybrids between I. wallichiana and I. polymorpha . The two specimens are from some distance apart; the coordinates of the second specimen (L. Wray 3628) are taken from the specimen label, where they are penciled in.

Saw (2023) placed I. perdana as a synonym of I. divergens . It is known from the type specimen and two other specimens, all from the same locality in Perak State. Lim (1998 a) illustrated two forms of leaves, one having 15–17 pinnae per side of the rachis with parallel veins and one having six pinnae with diverging veins. He described the fruits as like those of I. bicornis but with a flat top. Lim noted that I. perdana grew together with I. wallichiana and I. bicornis . Based on its unusual morphology, it could be a hybrid between these two species. Note that Ferreira et al. (in prep.) resolved I. perdana in the same clade as I. wallichiana .

In Sumatra, most specimens appear to be of the wallichiana morphotype, although there is some variation. Several specimens have undivided leaves, and one specimen (Jochanns 3193) from Batang Serangan has a note attached by J. Dransfield saying “This is identical to the populations of large, entire leaved Iguanura ……. named by Ridley I. spectabilis ” (i.e., like the major morphotype). The southernmost specimen in Sumatra (Grashoff 643) has an inflorescence with only two rachillae.

FIGURE 15. Distribution of morphotypes of Iguanura wallichiana .