Hanguana nana 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 : 103-105

2. Hanguana nana Randi & Škorničk. , sp. nov. — Fig. 2 ; Map 1

Hanguana nana is the smallest species in the genus so far and unique from its congeners by a slender upright stem entirely covered by leaves, lack of distinct terminal crown of leaves, and by an inflorescence/infructescence composed of only 1–3 partial inflorescences/infructescences each composed of only 1 or 2 branches. — Type: A. Randi AR-711 (holo WAN!;iso BO!), Indonesia, Kalimantan Tengah,Kotawaringin Barat,Arut Utara,Desa Nanga Mua, Bukit Telawih, S2°1'56.44" E111°48'53.37", 80 m alt., 11 April 2019, fruiting. For paratypes see underneath description .

Etymology. The species epithet is derived from Latin nanus = dwarf, and refers to the small habit of the plant.

Small solitary dioecious herb, erect, to 30 cm tall; stem terete, slender, 5–8 mm diam, cream to yellowish when fresh, with up to 20 more or less evenly distributed leaves (no formation of terminal crown); stolons absent. Leaves to 8–40 cm long (including pseudopetiole), smallest in the lowermost part of the stem, gradually larger distally, arching, bases imbricate; pseudopetiole 2–15 by 3–8 mm, accounting for 1/5–1/3 of entire leaf length, bluntly V-shaped in cross section, with sharp margins, winged 1/3–2/3 of the length, with grey floccose hairs on both sides; lamina elliptic, 6–27 by 2.5–6 cm (at widest point), base obtuse to attenuate, margins entire, slightly undulate, apex acuminate to caudate; adaxially mid to dark green, with sparse floccose hairs, glabrescent, abaxially paler green to glaucous; midrib adaxially weakly impressed, of the same colour as the rest of the lamina, abaxially round-raised, lighter green, almost glabrous and shiny abaxially; secondary parallel veins 5–8 on each side, indistinct; intercostal venation indistinct, but visible when fresh at adaxial surface, tesselate. Staminate inflorescence not observed. Pistillate inflorescence/infructescence arching to semi-pendulous, consisting of 1–3 partial inflorescences and a terminal spike; partial inflorescences ascending to rachis; peduncle and rachis together up to 20 cm long, brown to dark purple when fresh, flocculose; peduncle 1–11 cm by 1.2–2.5 mm diam, one sterile bract per peduncle, foliaceous, green to yellowish, persistent, narrowly ovate to narrowly elliptic, to 6 by 0.6–2 cm, sessile or nearly so (shortly clawed), apex narrowly acuminate; fertile bracts one for each partial inflorescence, similar to the sterile bract but rapidly diminishing in size distally and narrowly triangular to almost linear, the bract supporting the most basal partial inflorescence 16–23 by 2–4 mm, upper ones 4–7 by 2–4 mm; partial inflorescences each comprising 1 or 2 branches arising simultaneously from the axil of the subtending bract, slightly zigzag, branches at basal level 2–4.5 cm long, branches at upper levels usually shorter. Pistillate flowers scattered, solitary, sessile; perianth c. 5 mm across, composed of 6 tepals arranged in two whorls tightly clasping the fruit in fresh material, all tepals fleshy with prominent bulbous thickening at base (more prominent in outer whorl), externally dull green to reddish brown, internally light green, margins translucent white; outer tepals, semi-circular, 1–2 by 2–3 mm at base, free to base, externally sparsely arachnoid, internally glabrous; inner tepals larger than outer ones, circular or nearly so, c. 3 by 3 mm, free to base, glabrous both sides; staminodes 6, in two whorls, cream when fresh with brown apex, outer staminodes narrowly triangular, 0.6–0.8 by 0.2–0.3 mm at base, inner staminodes narrowly triangular, 1.3–1.6 by 0.3–0.5 mm at base, each basally sheathed with a broadly ovate to almost circular staminodial scale, c. 1 by 1 mm, light to dark brown, stigma 3-lobed, raised, 0.7–1 mm high, in mature fruits positioned centrally or very slightly obliquely, 1.4–2.5 mm diam, each lobe ovate, 0.6–1 by 0.5–0.8 mm, with blunt apex, slightly connate at very base, dark brown to black (in fruiting material). Ripe fruit bright pink to bright red, globose, 7–12 mm diam, glabrous or sometimes with sparse minute hairs; pericarp 0.8–1.3 mm thick. Seeds 1 per fruit (2 seeds in a single fruit have not been observed), 5–6 mm across, dark brown when mature; deeply bowl-shaped with slightly incurved margins and with large incurved appendage positioned on the distal part of the rim, 2–3 by 3–4 mm, externally with pointy projection at the outer surface, cavity filled with semi-translucent placental tissue.

Distribution — Currently known only from the Schwaner mountain range in West and Central Kalimantan province.

Ecology — Grows in lowland tropical broad-leaved mixed dipterocarp forest at about 50–800 m altitude. It is locally abundant in fully shaded understorey on hill slopes, valleys and along small rivers and streams.

Conservation status — This species is locally abundant in certain parts of Central and West Kalimantan. Although based on the EOO = 7 296 834 km 2 and AOO = 36 km 2 this species potentially qualifies for the categories Vulnerable and Endangered, respectively. We have observed that H. nana is growing in relatively undisturbed forest in Bukit Baka Bukit Raya National Park and the other localities are protected by mandatory regulations for a private forestry concession. We therefore assess this species as Least Concern (LC). An ex-situ initiative has been started with plants being cultivated at Arboretum Sylva UNTAN Pontianak.

Paratypes studied. INDONESIA, Kalimantan Tengah, Katingan ,upper Kating- an river, NW of Tumbang Samba, E112°50' S1°15', 50 m alt., 16 Nov. 1982, fruiting, J.P. Mogea & W.J.J.O. de Wilde 3498 (K000710092, L1418810) ; Kalimantan Tengah, Katingan, upper Samba river, NW of Tumbang Samba, E112°50' S0°50', 150 m alt., 23 Nov. 1982, fruiting, J.P. Mogea & W.J.J.O. de Wilde 3578 (L1418814) ; Kalimantan Tengah, Katingan, upper Samba river, NW of Tumbang Samba, E112°50' S0°50', 350 m alt., 13 Dec. 1982, fruiting, J.P. Mogea & W.J.J.O. de Wilde 4147 (L1419442) ; Kalimantan Tengah, Katingan, Tumbang Tubus , E112°51' S0°45', 150 m alt., 8 Aug. 1983, fruiting, J.F. Veldkamp 8133 (L1418830, L1418831, L1418832) ; Kalimantan Tengah, Katingan, Bukit Raya , E112°47' S0°45', 130 m alt., 5 Nov. 1982, H. Nooteboom 4170 (L1419439) ; Kalimantan Tengah, Katingan, Bukit Raya , E112°45' S0°45', 130 m alt., 26 Nov. 1983, fruiting, H. Nooteboom 4057 (L1419441) ; Kalimantan Tengah, Katingan, Tumbang Samba, Bukit Raya , E112°46'46.5" S0°42'56.6", 800 m alt., 17 Feb. 1995, fruiting, J.K. Jarvie & A. Ruskandi A. 6188 (L3893506) ; Kalimantan Barat, Sintang, Serawai, Bukit Baka Bukit Raya NP, Ella river , E112°17' S0°38', 315 m alt., 13 Oct 1993, fruiting, A.C. Church et al. 9 (L3807708, SING0203910 ) ; Kalimantan Barat, Sintang, Serawai, upper Uut Labang river, E112°38'56.2" S0°36'06.1", 750 m alt., 15 Oct. 1995, flowering, fruiting, A.C. Church et al. 2544 (K000710099, L3807706) .

Notes — All Hanguana species so far described from Borneo or elsewhere have a terminal crown of dense foliage with a leafless stem conspicuous especially in older plants. Apart of its small size, H. nana differs from all other species by an erect leaf-covered stem and by lacking a distinct terminal crown of leaves. The infructescence with only very few branches, each with only a few fruits and the bowl-shaped seeds with a large appendage curved inwards makes a unique set of characters for this species, easy to recognise even in herbarium material.

Figures

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

Fig. 2 Hanguana nana Randi & Škorničk.a.Habit in situ; b.lamina,adaxial surface;c. lamina,abaxial surface;d. inflorescence,showing sterile and fertile bracts; e. fruit, side view;f. fruit, top view; g. cross section of fruit; h. detail of inner tepals, staminodes and staminodial scales; i. seed with placental tissue; j. seed with large incurved appendage, side view;k. seed, top view (all:A. Randi AR-711, WAN). — Scale bars: b–d = 5 cm; e–g = 1 cm;h–k = 5 mm. — Photos:A. Randi.