Aspidistra longibracteata C. R. Lin & K. S. Nguyen 2024, sp. nov.

5. Aspidistra longibracteata C.R. Lin & K.S. Nguyen, sp. nov. (Fig. 5) Type:— VIETNAM. Bac Kan Province: type herbarium specimen prepared from plant cultivated at Guilin Botanical Garden (CN), 20 June 2022, Chun-Rui Lin 1563 (holotype: IBK, isotypes: IBK). Living plant was collected from northern Vietnam, Bac Kan Province, Ba Be National Park, evergreen broad-leaved forest on limestone hills at elevation 200–300 m a.s.l. around point 105.627°E, 22.404°N, not common, 20 August 2019. Additional specimen examined (paratype):— VIETNAM. Bac Kan Province: Ba Be National Park, 20 August 2019, Wei-Bin Xu, K. S. Nguyen & Chun-Rui Lin 13954 (IBK, HN). Diagnosis:— The new species is similar to A. luteo-rubra in the floral morphology, but clearly distinguished by its leaf blade thin and soft, narrow elliptic, base cuneate, bracts longer than perianth to 20–24 mm long, perianth lobes incurved, stamens frequently inserted at the middle of perianth tube, stigma slightly dilated, upper surface slightly concave and smooth, deeply 3-lobed at margin, lobes apex bent upwards. Herbs perennial, evergreen, rhizomatous. Rhizome creeping, subterete, 5–8 mm in diameter, covered with scales, internodes congested, roots elongate. Leaf sheath 3–4, pale purplish red, 2–7 cm long, enveloping base of petiole, fibrous when withered. Leaves solitary, 5–10 mm apart; petiole stiff upright, 10–18 cm long, ca. 2 mm wide, adaxially sulcate; leaf blade narrow elliptic, 20–32 cm long, 4.5–6.5 cm wide, green, base cuneate, gradually tapered to petiole, inequilateral, apex long acuminate, margin entire. Peduncle ascending or suberect, white with purplish red spots to purplish red, 8–32 mm long, with 3–5 bracts. Bracts gradually widened from below, the bracts at perianth base cymbiform or conduplicate, ovate to ovate-lanceolate, 20–24 mm long, 10–12 mm wide (being flatten), white or with pale purplish red spots, apex acuminate, longer than perianth; Flowers solitary, numerous. Perianth tubular, 15–17 mm long, 6-lobed apically; lobes broadly ovate, subequal, 4–5 mm long, 5–6 mm wide, outside yellow with purplish red stripes at the center or tip, sometimes even purplish red, inside yellow or sometimes yellow with purplish red at base, apex obtuse or nearly rounded slightly incurved; tube purplish red outside and dark purplish red inside, 10–12 mm long, the widest opening reaches 9–11 mm in diameter. Stamens 6, opposite to lobes, frequently inserted at the middle of perianth tube, occasionally at the upper part of perianth tube, positioned lower than stigma, filaments purplish red, ca. 1 mm long, anthers linear or narrowly oblong, 5–7 mm long and 1–1.5 mm wide, pollen yellow. Pistil rod-shaped, 11–12.5 mm long, equal to or slightly longer than tube, ovary inconspicuous, style cylindrical, glabrous, purplish red, ca. 2 mm in diameter, stigma dilated slightly, ca. 3 mm in diameter, upper surface white, central part slightly concave or sometimes flat, and with 3 radial, inconspicuous bifurcate slender grooves, deeply 3-lobed at margin, lobe apex slightly bent upwards. Phenology:— The new species was observed flowering from May to June. Etymology:— The specific epithet refers to its long bracts subtending the flower or perianth. Distribution and ecology:— Aspidistra longibracteata is currently found only in Ba Be National Park, Bac Kan Province, northern Vietnam. It grows under evergreen broad-leaved forest on limestone mountains, at elevation range of 200–250 m, not common. Similar species:— Aspidistra longibracteata is similar to A. luteo-rubra (K.S.Nguyen, Aver. & Tillich) Aver. & K.S.Nguyen in Chu et al. (2024: 166) in the floral morphology, but differs by its leaf blade thin and soft, green (vs. coriaceous, dark green), narrow elliptic (vs. narrowly ovate to elliptic), base cuneate (vs. round), bracts longer (vs. shorter) than perianth to 20–24 mm (vs. 3.5–10 mm) long, perianth lobes incurved (vs. erect to spreading), stamens frequently inserted at the middle (vs. lower third) of perianth tube, stigma slightly dilated (vs. narrowing), upper surface slightly concave (vs. flat), smooth (vs. finely papillose), deeply 3-lobed at margin, lobes apex bent upwards (vs. circular). The new species also similar to A. tenuistyla Aver., C.H.Nguyen & K.S.Nguyen in Chu et al. (2024: 162), but differs by leaf blade narrow elliptic (vs. narrowly ovate to elliptic), base cuneate (vs. round), bracts longer (vs. shorter) than perianth to 20–24 mm (vs. 9–17 mm) long, perianth lobes outside yellow with purplish red stripes to purplish red (vs. outside yellow with purplish red stripes to purplish red, inside yellow), inside yellow (vs. dark purple violet), perianth tube shorter to 10–12 mm (vs. 16.5–19.5 mm) and purplish red (vs. white) outside, stamens frequently inserted at the middle (vs. upper part) of perianth tube, style larger to ca. 2 mm (vs. 0.6–0.7 mm) in diameter. A detailed morphological comparison of three species is provided in Table 3.