Hanguana karimatae Randi & Škorničk., 2021

Randi, A., Wijedasa, L. S., Boyce, P. C. & Leong-Škorničková, J., 2021, Two new species of Hanguana (Hanguanaceae) from Kalimantan, Indonesia, Blumea 66 (1), pp. 101-105 : 101-103

1. Hanguana karimatae Randi & Škorničk. , sp. nov. — Fig. 1 ; Map 1

Similar to Hanguana podzolicola Siti Nurfazilah,Mohd Fahmi, Sofiman Othman & P.C.Boyce in general size and habit,but differs by smaller and sparser infructescences composed of 7 partial infructescences,the most basal partial infructescence composed of up to 8 branches and with median branches not exceeding 18 cm in length, larger pale yellow fruits to 10 mm diam with stigma strongly raised to 2 mm high, and 1 or 2 seeds per fruit, each with a small acute appendage (compared to infructescence composed of 9 partial infructescences, the most basal partial infructescence composed of up to 17 branches and with median branches up to 30 cm long, smaller dull pink fruits 5–7 mm diam with flat or only lightly raised stigma, and consistently single-seeded fruits with seeds having a broad and blunt appendage in H. podzolicola ). — Type: A. Randi AR-689 (holo WAN!; iso BO!), Indonesia, Kalimantan Barat, Kayong Utara, Kepulauan Karimata ( Karimata Island ), Desa Betok, S1°35'36.60" E108°53'13.20", 260 m alt., 20 Mar.2019,fruiting .

Etymology. The epithet of this species is derived from Latinised version of the Karimata Island, treated as feminine.

Large solitary dioecious herb, to 1.4 m tall, ascending crown of leaves; stem terete, to 3 m long, basal c. 1.6 m leafless, decumbent, 3–6 cm diam, dark brown, shiny, leaf scars conspicuous with fibres from the basal part of the leaf sheath, terminally ascending with spreading crown of up to 25 leaves; stolons absent. Leaves to 150 cm long, spreading then arching; bases imbricate; pseudopetiole 40–60 cm long, 1–2 cm wide at base, bluntly V-shaped in cross section, with sharp margins, covered with scattered floccose hairs on both sides; lamina elliptic, 70–100 by 15–25 cm, slightly undulate, base narrowly attenuate, margins entire, minutely recurved, apex narrowly attenuate with apicule to 2 cm long, adaxially dark green semi-glossy, abaxially paler green, shiny, very young leaves with scattered floccose silky hairs, glabrescent on both sides; midrib weakly impressed, of the same colour as the rest of the lamina adaxially, round-raised, lighter green, shiny abaxially. Staminate inflorescence not observed. Pistillate inflorescence / infructescence erect, comprising c. 7 partial, alternate-secund, thyrsoid inflorescences plus a terminal spike; partial inflorescences spreading, lowermost sub-erect, perpendicular or slightly descending distally; peduncle and rachis together to 90 cm long, green when fresh, with scattered floccose silky hairs; visible portion of peduncle to 45 cm long, to 1.7 cm diam at the bottom; one sterile bract per peduncle, foliaceous, persistent, ovate, to 60 by 15 cm (including 10 cm long claw/pseudopetiole), base obtuse, apex narrowly acuminate, caudate; fertile bracts one for each partial inflorescence, similar to the sterile bract distally, the bract supporting the most basal partial inflorescence c. 27 by 5 cm (claw/pseudopetiole c. 3 cm long, winged), narrowly ovate to narrowly elliptic, rapidly diminishing in size and becoming narrowly triangular to linear distally, fully reduced in the uppermost partial inflorescence; partial inflorescences each comprising up to 8 branches at basal level, fewer towards the apex of the inflorescence, branches arising simultaneously from the axis of the subtending bract, lateral branches progressively shorter; median branches at basal level to 18 cm long (shorter in upper partial inflorescences), unbranched or further branched to one order (with bracteoles c. 3 by 6 mm). Pistillate flowers scattered, solitary or in a pair, sessile, all with an associated minute bracteole; perianth composed of 6 tepals in two whorls tightly clasping ovary/fruit in fresh material, all tepals thick and fleshy with prominent bulbous thickening at base (more prominent in outer whorl), light green when fresh, margin hyaline translucent white; outer tepals broadly ovate, 2–3 by 2.5–4 mm, slightly connate at base, sparsely arachnoid externally, glabrous internally; inner tepals circular or nearly so, 3–4 mm diam, free to base, externally with a few arachnoid hairs at apex, glabrous internally; staminodes 6, in two whorls, cream to pale green when fresh, outer staminodes triangular, 0.3–0.4 by 0.2–0.4 mm at base, inner staminodes narrowly triangular, 1.2–1.8 by 0.2–0.4 mm at base, basally sheathed with staminodial scale semi-circular, c. 1–1.5 by 1.2–1.8 mm, with somewhat retuse apex, dark brown with translucent margin, stigma 3-lobed, strongly raised, 1.3–2 mm high, in matured fruits positioned strongly obliquely, c. 3 mm diam, each lobe ovate to bluntly triangular, 1–2 by 0.8–1.2 mm, apex acute, dark brown (fruiting stage). Ripe fruit pale yellow (the dark seed colour is visible through the increas- ingly translucent pericarp), globose, 6–10 mm diam, glabrous or with sparse silky arachnoid hairs, pericarp 1–2 mm thick. Seeds 1 or 2 per fruit, 4 – 5 mm across, dark brown to nearly black, deeply bowl-shaped with incurved margins, with a small acute appendage positioned on the distal part of the rim; cavity filled with placental tissue.

Distribution — Hanguana karimatae is so far known only from Karimata Island, an isolated mountainous island off the coast of Kalimantan Barat province, Indonesia.

Habitat & Ecology — Occurring in primary lowland forest, on the sides of a small rocky stream with clear water at 250– 500 m altitude.

Conservation status — Only three mature individuals and one young individual are recorded for this species in suitable habitats in the same general area with EOO = 0.497 km 2 and AOO = 8 km 2. Although the island is surrounded by a marine conservation area, the habitat on the island is not totally protected by Indonesian law. Threats to habitat, such as logging and forest fires, were observed in the vicinity of the area where this species occurs. We therefore assess this species as Criti- cally Endangered B1ab(iii) + B2ab(iii); D. Ex-situ conservation of this species is urgently needed.

Notes — Hanguana karimatae is morphologically most similar to Hanguana podzolicola , a species known to occur in southernmost part of Peninsular Malaysia and Singapore ( Siti Nurfazilah et al. 2010, Niissalo & Leong-Škorničková 2017). In addition to the main morphologic differences outlined in the diagnosis, the two species are also very different in their habitat. Hanguana karimatae grows on the sides of small rocky streams with clear water at 250–500 m alt., while H. podzolica grows in seasonally swampy peat forests at 40–60 m alt. in Peninsular Malaysia while in Singapore it is strictly a swamp-forest species, occurring in locations with permanently wet or flooded soil.

Figures

Map 1 Distribution map of Hanguana karimatae and H. nana.

Fig. 1 Hanguana karimatae Randi & Škorničk. a. Habit in situ; b. habit of single plant; c. lamina, adaxial and abaxial surface; d. infructescence with sterile and fertile bracts; e. detail of inflorescence branch; f. fruit, side view; g. longitudinal section of fruit; h. fruit, semi-top view, showing detail of stigma; i. crosssection of fruit, showing two seeds; j. detail of inner tepals, staminodes and staminodial scales; k. seed, top view; l. seed, front view (all: A. Randi AR-689, WAN). — Scale bars: b, d = 50 cm; c = 20 cm; e = 2 cm; f–j = 5 mm; k–l = 3 mm. — Photos: A. Randi.