Biancaea scabrida L.M.Choo, 2021

Choo, Le Min, 2021, Biancaea scabrida, a new species of the Caesalpinia group (Fabaceae) from Peninsular Malaysia, Phytotaxa 525 (4), pp. 251-257 : 253-256

Biancaea scabrida L.M.Choo , sp. nov. ( Figs. 1–2 )

TYPE:— Peninsular Malaysia, Kelantan, Gua Musang , 23 Feb 1972, Loh Hoy Shing FRI 19256 (holotype SING! [ SING0256191 ] (fl); isotype KEP [ KEP136564 ] (fl); isotype L! [ L1976278 ] (fl)) .

Diagnosis:— This species is the most similar to Biancaea parviflora and Biancaea oppositifolia in its small, compact flowers, borne on a long inflorescence, which are very much smaller than other species in the genus. However, it differs from both species by the sepals which have short, stiff scabrid hairs, and by the stiff and hispid hairs on the pistil, which is especially visible at the style where the hairs are sticking out, as compared to B. parviflora and B. oppositifolia where the hairs are soft and adpressed. It can be distinguished from B. parviflora by its larger and ovate-elliptic leaflets, fewer pinnae per rachis (2–6 pairs) and fewer leaflets per pinna ((3–)5–9 pairs). It can also be distinguished from B. oppositifolia by its alternately arranged leaves and inflorescence branches, and also by the lack of large, persistent and suborbicular stipules.

Description:— Thorny climber. Mature stem not known. Young stem brown to reddish brown, surface shallowly striate, minutely pubescent with small upright or tomentose hairs, armed with regularly-spaced short incurved spines. Stipules not seen. Leaves alternate; petiole (1.8–) 3.5–4 cm, surface slightly furrowed, covered in short tomentose hairs; rachis 8.6–17.1 cm, tomentose as in petiole; rachis spines incurved, 2–3 × 1–2 mm, one pair at the base of each pinna and 1–3(–5) pairs between adjacent pinnae; pinnae 2–6 pairs, 4.1–9(–16) cm long. Leaflets opposite, (3–)5–9- jugate, opposite; petiolule ca. 1 mm long; leaflet lamina unequally ovate to elliptic, (1.2–)1.6–5.3 × (0.4–) 0.7–1.9 cm, base obtuse to obliquely truncate, apex acute to obtuse, but rounded at the very tip; upper surface dull grey brown when dry, glabrous, but pubescent down the midrib; lower surface reddish or yellow brown when dry, glabrous, except for midrib which is very sparsely pubescent; midrib slightly raised above and raised below, secondary veins slightly raised both above and below, tertiary venation or reticulations not clearly seen above but more conspicuously raised below; glands absent. Inflorescences paniculate, axillary or supra-axillary or terminal, 18–30 × 5.4–13.3 cm, branching out in racemes. Individual racemes ca. 3–7 in each panicle, 7–23.1 cm long; flowering rachis minutely pubescent or tomentose with short upright hairs; bracts triangular, 1–2 × 1–1.5 mm long, with short tomentose hairs as in the rest of the inflorescence, early caducous and only seen in developing inflorescences or at the top of developing inflorescences where the buds are still compact; bracteoles absent. Flowers: ca. 20–50 in each individual raceme; pedicels 3–4 mm long, pubescent; buds ovoid, ca. 3 × 2 mm, pubescent with stiff short hairs; receptacle 2–3 × 1–2 mm. Sepals 5, subequal, broadly triangular to ovate, light green when fresh, 2.1–3.3 × (0.7–) 1–1.8 mm, outer surface hairy with short stiff scabrid hairs, margins densely hairy, inner surface sparsely hairy with scabrid hairs mostly at the middle of the sepal. Petals 5, subequal, elliptic to obovate to narrowly ovate, bright yellow when fresh; 3–4.5 × 1.1–1.8 mm, of which claw 0.5–0.8 mm long, limb glabrous on both surfaces and pubescent at the claw, veins visible on yellow surface as brown lines; standard petal thicker than the rest, oblong to broadly oblong, 3.8–4.5 × 1.3–2 mm, of which claw 1–1.8 mm long, outer surface densely pubescent on the lower half of the petal, inner surface pubescent in the middle with villous hairs, margins at the claw densely pubescent. Stamens 10, filaments light green, 3.1–6 mm long, densely villous at the base up to more than half its length, glabrous at the top; anthers dorsifixed, narrowly lanceolate or ovate, dark brown, 0.6–0.8 × 0.2–0.4 mm. Pistil 1; ovary sessile, oblong to elliptic to lanceolate, 1.6–2.3 × 0.8–1 mm, densely pubescent to hispid with stiff upright hairs; style 3.2–3.8 mm long, pubescent but becoming sparse up the style; stigma black, slightly thickened and margin glabrous or ciliate with very short hairs, opening ca. 0.3 mm in diameter. Young pods flat and woody, shape obovate to elliptic, but obliquely truncate to acute at the tip, yellow brown when dry, 4–4.6 × 2.1–2.4 cm, base rounded, sessile (no ovary stipe), apex unequally elongated and pointed on the dorsal (adaxial side); surface smooth and glossy, puberulous with very fine short upright yellow hairs that are scarcely visible; fruiting pedicel 4–6.5 mm long, articulated where it joins the receptacle. Seed 1, a flattened elliptic disk, 1.5 × 1–1.2 × 0.1 cm, surface dark brown, with horizontal lines appearing as fine cracks encircling the seed widthwise.

Distribution: — Biancaea scabrida is known from two locations in Peninsular Malaysia, Gua Musang in the State of Kelantan and Tasik Temenggor in Perak.

Habitat: —Limestone hill.

Etymology: —The specific epithet is derived from the Latin word scaber, which means rough to the touch because of numerous minute projections. This refers to the hairs on the sepals which are short, stiff and scabrid on both surfaces.

Provisional IUCN conservation assessment: —Vulnerable (VU D2). In the type locality of Gua Musang, Kelantan, and the second locality of Tasik Temenggor in Perak, the species has been described as common and with many individuals. However, Gua Musang is quite disturbed, and while Tasik Temenggor is part of a state park protected area, it can still be logged in the future ( Schwabe et al., 2015). Given the few known localities of the species, and the plausible threat of mining activities on limestone hills in Peninsular Malaysia, any future development activities in these two localities could cause the species to become endangered or extinct in a short amount of time ( Kiew et al., 2017; Rahman & Kiew, 2018).

Additional specimens seen. Peninsular Malaysia: — Perak, Belum Forest Reserve, Limestone Island Temenggor Lake [Tasik Temenggor], 24 Feb 1994, Chua L. et al. FRI 40460 ( KEP! [ KEP187987 , KEP187988 , KEP187989 ]) (fl); ibidem, 21 Apr 1994, I. M. Turner 94-91 ( SING! [ SING0256192 ], SINU! (2 sheets)) (fl, fr) .

Figures

FIGURE 1. Photo of the holotype of Biancaea scabrida.

FIGURE 2. Illustration of Biancaea scabrida. A: inflorescence; B: flower; C: inner surface of receptacle and sepals; D: outer surface of receptacle and sepals; E: inner surface of lateral petal; F: inner surface of standard petal; G: inner surface of basal petal; H: pistil; I: closeup of stigma; J: stamen; K: seed; L: pod. Drawn by Loh Xiang Yun from the holotype Loh FRI 19256, SING[SING0256191] for A, and from Turner 94-91 [SINU] for B-L.