Aspidistra nigrescens Aver. & C.H.Nguyen, 2025

Nguyen, Cuong Huu, Duong, Nam Van, Bui, Doi The, Tran, Hung The, Phan, Quyet Thanh, Le, Vu Khanh, Nguyen, Ly Van, Maisak, Tatiana V. & Averyanov, Leonid V., 2025, Aspidistra nigrescens (Asparagaceae, Convallarioideae), new species of “ Aspidistra zinaidae group ” from central Vietnam, Phytotaxa 701 (1), pp. 115-120 : 116-119

Aspidistra nigrescens Aver. & C.H.Nguyen , sp. nov. ( Fig. 1 & 2 )

Type: — VIETNAM. Quang Binh Province: Le Thuy District, Kim Thuy Municipality , secondary and primary fractionally logged evergreen broad-leaved forest on very steep hill slopes composed by gray and yellow solid marble-like limestone at elevation 800–900 m a.s.l. around point 16º57.4N 106º35.3E, terrestrial herb in shady places, flowers white with dark violet, almost black lobes, locally common, 10 November 2024, Nguyen Huu Cuong, Nguyen Van Ly, Phan Thanh Quyet, Duong Van Nam, Le Thi Phuong Thao, L. Averyanov, T. Maisak, AL3654 (holotype: VNF, isotypes: LE LE01277745 https://en.herbariumle.ru/?t=occ&id=255607; LE01277746 https://en.herbariumle.ru/?t=occ&id=255608; photos pf plant used for the preparation of the type specimens: LE01255443 https://en.herbariumle.ru/?t=occ&id=249265; LE01255489 https://en.herbariumle.ru/?t=occ&id=249264 & LE01255499 https://en.herbariumle.ru/?t=occ&id=250162) .

Paratype: — VIETNAM. Quang Binh Province: Le Thuy District, Kim Thuy Municipality, secondary and primary fractionally logged evergreen broad-leaved forest on very steep hill slopes composed by gray and yellow solid marble-like limestone at elevation 800– 900 m a.s.l. around point 16º57.4N 106º35.3E, terrestrial herb in shady places, flowers white with dark violet, almost black lobes, locally common, 10 November 2024, Nguyen Huu Cuong, Nguyen Van Ly, Phan Thanh Quyet, Duong Van Nam, Le Thi Phuong Thao, L. Averyanov, T. Maisak, DCKNT-NR 036 ( VNF).

Diagnosis: — Aspidistra nigrescens differs from morphologically most similar A. heterocarpa mainly in leaves aggregated at rhizome apex (vs. rhizome leafy throughout), lanceolate to broadly lanceolate leaf blade (vs. leaf blade elliptic), perigone tube urceolate, 6.5–8.5 mm long (vs. perigone tube campanulate, 5–5.5 mm long), perigone lobes adaxially black, broadly triangular sagittate, as long as wide (vs. perigone lobes adaxially dark purple, ovate oblong, distinctly longer than wide), filaments separate (vs. connivent forming annular structure), anthers oblong, 2.5–3 mm long, 1 mm wide (vs. anthers bean-shaped, 1.8–2.2 mm long and wide), stigma hemispheric, 2.4–2.6 mm across (vs. stigma flat or slightly convex, 2.8–3.2 mm across), and fruits finely rugose, 1–1.7 cm in diameter (vs. fruits smooth, 0.7–1 cm in diameter).

Etymology:— The species epithet refers to the black color of perigone lobes.

Description:—Herb terrestrial perennial rhizomatous, with orthotropic, ascending or suberect, rigid, epigeios rhizome and erect leaves. Rhizome rigid, to 6(8) cm long, simple or branching, 3–4.5 (5) mm in diameter, densely nodal, with numerous wiry, rigid, semi woody, roots, leafy at apex. Cataphylls convolute, cuneate, to 10–14 cm long, brownish when young, early splitting into dull gray-brown, papyraceous or fibrous remains. Leaves (3)4–5(6) densely arranged at the apex of rhizome, straight or hardly arching, (50)60–70(75) cm long, petiolate; petiole stiff, straight, (22)25–32(34) cm long; leaf blade, lanceolate to broadly lanceolate, tapering at base and acute apex, (28)30–36(40) cm long, (2.6)2.8–3.2(3.4) cm wide, more or less flat, uniformly grassy green on both surfaces, with prominent midvein and 3–4 secondary veins well seen on both sides (immersed adaxially, convex abaxially), arising from midvein in basal half of leaf blade. Flowers odorless, commonly 1 to 3 on an individual stem, pedunculate, horizontal or nutant, not widely opening. Peduncle purple, (3.5)4–7(8) mm long, 1–1.5 mm in diameter, with 3(4) bracts, the two distal of which adjacent to perigone tube; bracts broadly ovate, concave, papyraceous to scarious, white, finely purple speckled, obtuse, (3.5)4–5.5(6) mm long and wide. Perigone urceolate, (9)10–12(13) cm long, (6)6.5–7.5(8) mm in diameter, of 6 lobes; perigone tube (6.5)7–8(8.5) mm long, (6)6.5–7.5(8) mm in diameter, glossy white outside, black inside, white at filament insertion area; perigone lobes subsimilar, in two distinct circles, broadly triangular sagittate, almost orbicular at apex, fleshy, smooth, straight or hardly reflexed, (4)4.2–4.5(4.6) mm long and wide, with adaxial surface smooth, black, and abaxial surface glossy white with black margin. Stamens 6; inserted at middle part of tube, filamentose; filaments white, very short, fleshy, 0.5–0.6 mm long, 0.6–0.7 mm across; anthers introrse, oblong, 2.5–3 mm long, about 1 mm wide; pollen pale yellow. Pistil entirely white; ovary inconspicuous; style cylindrical 8.5–9.5 mm long, (1.9)2(2.1) mm wide, slightly inflated at the base and apex; stigma capitate, (2.4)2.5(2.6) mm in diameter, hemispheric, orbicular, entire to indistinctly 3-lobed, finely rugose, sometime with 3 hardly visible irregular radial fissures. Fruit berry-like, globular, (10)12–15(17) mm in diameter, dirty green to pale dirty purple-brown, smooth or finely rugose, with 1–2(3) seeds.

Distribution:— Vietnam, Quang Binh Province (Le Thuy District, territory of Dong Chau–Khe Nuoc Trong Nature Reserve). Endemic of limestone areas in central Vietnam.

Ecology and phenology: —Terrestrial rhizomatous herb. Primary and secondary fractionally logged evergreen broad-leaved forests on steep hill slopes composed by gray and yellow solid marble-like limestone at elevation of 800–900 m a.s.l., commonly in deep shade. Locally common. Flowers in October–November.

Conservation: —The species was observed in its single know location as a common plant, which can survive in secondary and degraded forests on the territory that is currently is officially protected. Following criteria and terms of the Red List IUCN (2024) we preliminarily estimate the conservation status of newly discovered species as a least concern (LC).

Notes: — Aspidistra nigrescens belongs to group of Vietnamese species with small, 6-morous, campanulate or urceolate flowers with dark purple to black lobes of perigone, and stamens inserted near middle of perigone tube. In our earlier publication ( Averyanov et al. 2019) it was provisionally named as “ A. zinaidae group”. This group beside species described here includes Aspidistra erosa Aver., Tillich, T.A.Le & K.S.Nguyen in Averyanov et al. (2019: 102), A. heterocarpa Aver., Tillich & V.T.Pham in Averyanov et al. (2018: 4) var. heterocarpa , A. heterocarpa var. echinata Aver., Tillich & T. A. Le in Averyanov et al. (2018: 7), A. multiflora Averyanov & Tillich (2015: 368) , and A. zinaidae Averyanov & Tillich (2012: 8) . The group is morphologically well segregated and forms rather isolated, monophyletic, highly supported clade in molecular cladistics (Vislobokov 2024 pers. comm.). Among members of this group newly discovered species morphologically is most close to A. heterocarpa (including its varieties) sharing such particular characters as cylindric, drumstick-shaped pistil hardly broadening at the base and apex. However, both species differs in a series of morphological characters indicated in diagnosis and the key for identification of species mentioned group placed below.

Figures

FIGURE 1. Aspidistra nigrescens. Plant in natural habitat. Photos by Cuong Huu Nguyen.

FIGURE 2. Aspidistra nigrescens. A. Flowering plant in natural habitat. B, C. Basal part of plants in nature with intact flowers. D. Basal part of plant with mature fruit. E. Flattened plant with flowers and fruit. F. Peduncle and flower, side view. G. Peduncle bracts. H. Peduncle and flower with bracts removed. I. Flower, sagittal section, abaxial side. J. Flowers, front view. K. Flower, tangential section showing intact pistil. L. Flower, tangential section showing stamens. M. Pistil, side view. N. Stigma, view from above. O. Anthers. P. Fruits with peduncles, side view.Q. Fruits, frontal and half-side views. R. Fruit, sagittal and cross sections. Photos, graphic correction, and design by L. Averyanov and T. Maisak from living plants prior to the preparation of the type herbarium specimens AL3654.