Hanguana ensifolia Hroneš, UvÍrová, Dančák & P. C. Boyce, 2025

Hroneš, Michal, UVÍroVá, Alena, Dančák, Martin, Boyce, Peter C. & Leong-ŠkorničkoVá, Jana, 2025, Hanguana ensifolia and H. flavescens, two new species of Hanguana (Hanguanaceae) from western Sarawak, Borneo, Willdenowia 55 (1), pp. 259-269 : 261-264

Hanguana ensifolia Hroneš, UvÍrová, Dančák & P. C. Boyce , sp. nov. – Fig. 2, 3.

Holotype: Malaysia, Sarawak, Kuching Division , Kuching District, Semenggoh Nature Reserve, lowland mixed dipterocarp forest near arboretum trail, 515 m west from main entrance, 1.3992774°N, 110.3201979°E, 71 m a.s.l., 1 Feb 2024, Hroneš & Uvírová 2024/01 (SAR!).

Diagnosis — Hanguana ensifolia is similar to H. bakoensis Siti Nurfazilah & al. but differs by being taller, 1.1–1.6 m tall (vs to 1 m in H. bakoensis ), with leaf blade abaxially purplish, purplish green to light green (vs bluish green), pseudopetiole accounting for c. 1/3 of entire leaf length (vs c. 1/2 of entire leaf length), infructescence deflexed to prostrate (vs declinate), outer tepals distinctly swollen (vs not swollen) and fruits globose, ripening dull red (vs compressed globose, very weakly 3-lobed, ripening medium pink to magenta).

Description — Herbaceous, dioecious, solitary or clump-forming mesophyte 1.1–1.6 m tall. Rhizome ascending, sparsely covered by fibrous remnants of sheaths; stolons absent. Stem terete, very short, c. 15 cm long, to 2 cm in diam., fully covered by sheaths when young, basally erect, with age becoming leafless and sparsely covered by fibrous remnants of leaf sheaths, terminally with a crown of 10–14 leaves. Leaves tristichously arranged, 70–150 cm long, erect then gently arching, bases imbricate with hyaline margins (young leaves), turning brown and erose-marcescent with age; pseudopetiole 30–45 cm long, c. 1 cm wide, accounting for c. 1/3 of entire leaf length, rounded channelled with sharp margins, basally sparsely greyish white floccose, apically glabrous; leaf blade 95–105 × 4–4.5 cm, very narrowly elliptic, linear-lanceolate to ensiform, base long narrowly attenuate, tip long narrowly attenuate with apicule 7–9 mm long, leathery, almost flat to slightly undulate on margins, adaxially mid- to dark green with somewhat indiscernible, greyish green to blackish green, transverse variegation, shiny, abaxially purple, purplish green to light green, semi-matt when dry, shiny when wet, glabrous to nearly glabrous on both surfaces; midrib distinctly impressed, pale whitish green adaxially, rounded raised, olive green, glabrous and shiny abaxially. Male inflorescence not observed, female inflorescence not observed. Infructescence distinctly deflexed to prostrate, consisting of up to 6 partial, whorled, alternate-secund, spiciform infructescences ascending at an angle of 70°–80°, plus a terminal spike; peduncle and rachis together to 80 cm long, pale green to purplish green when fresh, glabrous, visible portion of peduncle to 35 cm long; sterile bracts 1 or 2 per peduncle, foliaceous, persistent, lanceolate with a basal claw, to 30 cm (incl. 2 cm long claw/pseudopetiole) × c. 3.5 cm; bracts subtending lower partial infructescences similar to sterile bracts, diminishing in size and becoming narrowly triangular distally along infructescence, fully reduced in uppermost partial infructescences; bract supporting most basal partial infructescence c. 15 × 2 cm (incl. c. 2 cm long claw), all bracts of same colour as leaves, glabrous on both surfaces; partial infructescences each consisting of up to 7 branches at basal levels (gradually fewer with up to 1 branch toward apex of infructescence), branches arising simultaneously from axil of subtending bract, 1.8–2.5 mm in diam., usually unbranched or with up to 3 branches, to 8.5 cm long, with up to 20 fruits each; all branches covered by scattered, minute, curly, white hairs. Female flowers scattered, solitary, or clustered up to 4 at terminal parts of branches, sessile, all with an associated minute bracteole; perianth consisting of 6 tepals in 2 whorls tightly clasping ovary/fruit in fresh material, light green, margin 0.5–0.8 mm wide, hyaline translucent white (turning brown with age); outer tepals distinctly swollen, broadly ovate, c. 2 mm long, 3–3.5 mm wide, connate to 1/2 their length (c. 1.5 mm), glabrous; inner tepals almost orbicular to ovate-orbicular, 3–3.5 mm long, 2.5–3.5 mm wide, basally imbricate but free, glabrous; staminodes 6, in 2 whorls, whitish green, triangular to narrowly triangular, outer staminodes 0.3–0.4 mm long, c. 0.3 mm wide at base, inner staminodes longer, 1–1.4 mm long, c. 0.2 mm wide at base, each basally sheathed with broadly orbicular to triangular-orbicular, apically blunt to shallowly bilobed staminodial scale, 0.5–0.6 mm long, 0.9–1.2 mm wide, dark brown with irregular, translucent to light brownish yellow margin. Stigma 3-lobed (trefoil-like to triangular with rounded edges), 2–2.2 mm in diam., each lobe 1–1.1 mm long (fruiting material), almost orbicular to elliptic with rounded apex, lobes connate to c. 1/2 their length, dark brown to black at fruiting stage, usually positioned at 160°–180° in ripe fruit. Fruit globose, 9–10.5 mm in diam., dull red, finally ripening black; pulp 1.5–4 mm thick, whitish yellow to yellow, fairly hard. Seed 1 or 2 per fruit, c. 5 × 3.5 mm, dark brown, bowl-shaped, with slightly incurved margins, deeply excavated, without any discernible appendage on rim, cavity filled with placental tissue.

Distribution and habitat — Known from several locations in westernmost Sarawak (Kuching and Betong Divisions, Fig. 1) with the highest concentration observed in Kuching and Lundu Districts, Kuching Division. It grows in lowland mixed dipterocarp forests, kerangas, peat swamp forests and transitional forest types between these, usually in shady to semi-shady places on flat land or on small ridges, at altitudes of 50–180 m a.s.l.

Conservation status — Hanguana ensifolia is endemic to Borneo and it is known from eight locations (sensu IUCN 2024), most of them recorded before 1989. While the overall extent of occurrence ( EOO) estimated from historical and recent locations is c. 1900 km 2, its area of occupancy ( AOO) could be estimated as 32 km 2. The current status of most populations is unknown, but the habitat is heavily degraded or completely destroyed at about half of its sites (e.g. Sampadi Forest Reserve, Setapok Forest Reserve, Siol). Because we expect further decline in the quality of the habitat, H. ensifolia is assigned a preliminary conservation status of EN B1ab(iii)+2ab(ii,iii) according to the IUCN Red List categories and criteria ( IUCN 2024).

Etymology — The Latin adjectival epithet ensifolia means with sword-like leaves and refers to the long, narrow leaf blades, which are rather unusual for Hanguana species.

Additional specimens seen — MALAYSIA, SARAWAK, KUCHING DIVISION, LUNDU DISTRICT: Lundu road, Kpg. Rasau, path to G. Besi, kerangas forest, 10 May 1983, Ilias Paie 46077 (K 000710134, KEP 36772, SAR); Sampadi Forest Reserve, heath forest, 30 Jan 1989, Abang Mohtar 54854 (K 002791927, KEP 139702); Sampadi Forest Reserve, kerangas forest, 16 Sep 1989, Abang Mohtar 53083 (KEP 75351, SAR); ibid., 16 Sep 1989, Abang Mohtar 53084 ( SAR); Matang Wildlife Centre, Sg. Rayu, lowland forest, 4 Mar 1999, Stephen Tao & al. 79517 ( SAN). — KUCHING DISTRICT: Kuching, Sep 1905, John Hewitt 134 ( SAR); Siol, Apr 1906, John Hewitt 370 ( SAR); Kuching, Setapok F. R., in peat swamp forest, 14 Nov 1959, James Aidan Robb Anderson & Zen bin Osman 11729 (K 000710121 & 000710122, SAR); Gunung Selang, proposed Matang National Park, Matang, Kuching, mixed dipterocarp forest on ridge, 180 m a.s.l., 4 May 1987, Bernard Lee Meng Hock 54196 (K 000710147 & 000710147, SAR); Semengoh [sic!] arboretum, on flat land, 23 May 1974, Silvester Laijanai 34199 ( SAR); Semengoh [sic!] forest station, c. 25 m a.s.l., 7 Mar 1994, Peter C. Boyce 764 (K 000710170). — BETONG DIVISION, BETONG DISTRICT: Simanggang, Triso P. F., Nov 1959, James Aidan Robb Anderson s.n. ( SAR).