Peliosanthes nivea Averyanov & Tanaka (2012: 157) var. acutiloba N.Tanaka & Aver., 2023

Averyanov, Leonid V., Nguyen, Van Canh, Tanaka, Noriyuki, Nguyen, Khang Sinh & Maisak, Tatiana V., 2023, Three new taxa and two noteworthy species of Peliosanthes (Asparagaceae, Convallarioideae) from Laos and Vietnam, Phytotaxa 609 (3), pp. 209-221 : 215-217

Peliosanthes nivea Averyanov & Tanaka (2012: 157) var. acutiloba N.Tanaka & Aver. , var. nov.

(Fig. 5 in Averyanov et al. 2017; LE: LE 01122836 https://en.herbariumle.ru/?t=occ&id=99443)

Diagnosis: —Similar to P. nivea var. nivea , but distinguishable mainly by the somewhat basipetal (vs. acropetal) blooming, often shorter (2–4.5 vs. 3–8 mm) floral bracts, longer pedicels (1.4–2.4 vs. 1–1.5 mm), narrower (1.8–2.1 vs. 5–5.5 mm wide) triangular ovate (vs. broadly ovate or broadly triangular ovate) perianth segments slightly imbricate only basally (vs. largely imbricate in the lower half), more slender conoid pistil without distinct intercarpellary wings (vs. with prominent intercarpellary wings in the distal half of pistil).

Type:— LAOS. Type herbarium specimen prepared on 15 April 2017 by L. Averyanov from flowering cultivated plants grown from seeds collected in Khammouane Province, Thakhek District , near Thamnangene Cave , around point 17°26.634N 105°56.872E, on vertical limestone cliff, at an elevation of 157 m a.s.l. on 3 November 2013, E. Konstantinov K 249 . Holotype LE01049913 (https:// en.herbariumle.ru/?t=occ&id=2672). Photos of the cultivated plants— LE01122836 (https://en.herbariumle.ru/?t=occ&id=99443).

Etymology:—The varietal epithet refers to the acute perianth segments.

Description (the description below is based on 3-year-old plants grown from seed, hence the sizes of various portions, especially vegetative ones such as leaves, are likely to be smaller than those in adult plants in the wild):— Herb lithophytic, rhizomatous, acaulescent, evergreen perennial. Rhizome plagiotropic, horizontal or ascending, simple to few branching, 0.8–1.2(1.6) cm long, (2.5)3–4(4.5) mm in diameter, covered with few remnants of papyraceous dull yellowish bracts. Roots wiry, rigid, somewhat fleshy, dirty gray. Stem ascending or erect, (0.8)1–1.2(1.4) cm high, covered with few linear or lanceolate papyraceous whitish bracts to 3 cm long, (1.2)2(2.5) mm wide (when flattened). Leaves (6)8–12(14) cm long; petiole rigid, stout, usually curved, (2.5)3–3.5(4) cm long; leaf blade elliptic, (4.5)5–8(9) cm long, (1.8)2–3(3.4) cm wide, leathery, glabrous, somewhat rugose, adaxially grass green, glossy, abaxially light green, acute or shortly acuminate, with (5)6–9(11) main longitudinal veins; secondary transverse veinlets distinct, numerous, closely spaced, nearly parallel to each other and perpendicular to longitudinal veins. Flowering stem (peduncle and inflorescence rachis) (3)3.5–4.5(5) cm long, pale green, shorter than leaves; peduncle erect, stout and straight, (1)1.2–1.6(1.8) cm long, (1)1.2(1.4) mm in diameter, ebracteate or at middle with 1–2 lanceolate sterile bracts 3–4 mm long, at the base with few small, light brownish, papyraceous bracts; rachis (1.6)1.8–3.5(4) cm long. Floral bracts 2 (outer bract and inner bracteole), smaller above, light green to white, scarious, lanceolate or (narrowly) triangular lanceolate, acute; bract descending, (2)2.5–4(4.5) mm long, (0.7)0.8–1.2(1.3) mm wide; bracteole borne crosswise to bract and perpendicular to rachis, twice smaller. Flowers (4)5–12(14) flowers per rachis, somewhat basipetally blooming, drooping, solitary in bract axils, campanulate, not widely opening, (3.5)4–4.5(5) mm high, (6)6.5–7.5(8) mm (when flattened 11–12 mm) wide in diameter. Pedicel cylindric, down-curved, light greenish, (1.4)1.6–2.2(2.4) mm long. Perianth distally 6-cleft, fleshy; tube broadly obconic, (2.8)3–3.2(3.4) mm in diameter, (0.9)1(1.1) mm high; segments 6 in 2 whorls of 3, subsimilar in shape and size, abaxial side white to pale green with purplish margins, adaxial side dark dull violet, narrowly triangular ovate, acute to subacute with obtuse tip, (3)3.2–3.8(4) mm long, (1.8)1.9–2(2.1) mm wide. Corona somewhat depressed (conoid) hemispheric, dark purple-violet, 0.5–0.7 mm high, obscurely hexagonal at base, (4.2)4.4–5(5.2) mm in diameter, apical margin 6-subdentate, apical opening obscurely hexagonal to almost rounded, (1.3)1.4–1.5(1.6) mm in diameter. Anthers 6, sessile, introrse, (broadly) ellipsoid, about 0.4 mm long and wide, pale dull yellowish green. Pistil half-inferior, distal exposed portion narrowly conoid, 1.5–1.6 mm high, 0.9–1 mm across at base, with 3 longitudinal ridges decurrent from stigmatic lobes, without distinct intercarpellary wings at least in distal half, dark purple-violet; ovary internally incompletely 3-septate, each locule adaxially open, containing 2–3(4) ovules on central basal placentae; stigma sessile, 3-dissected, lobes elliptic, ca. 0.5–0.6 mm long. Seed broadly ellipsoid to almost globular, 11–13 mm long and wide, dark blue, glossy.

Ecology and phenology:—Lithophytic herb on shady vertical rocky cliffs in primary or secondary lowland evergreen broad-leaved forests on limestone at the elevation of 100–200 m a.s.l. Flowers in April.

Conservation status:—Only a few mature individuals were found in the type locality. The natural environment, including the habitat, had been largely altered by the local development for promoting tourism. For lack of sufficient data on the occurrence, the conservation status of this new variety is estimated as “Data Deficient” (DD), according to the criteria proposed by IUCN (2022).

Distribution:— Laos, Khammouane Province (Thakhek District, Thamnangene Cave). Known only from the type locality.

Notes: —The type specimen of Peliosanthes nivea var. acutiloba is the same as the material used previously for recording P. nivea in Laos ( Averyanov et al. 2017).

Peliosanthes nivea var. acutiloba is similar to P. nivea var. nivea and also to P. virescens (described in this paper), P. argenteostriata Averyanov & Tanaka (2012: 153) and P. convallarioides Aver., N.Tanaka & K.S.Nguyen in Averyanov et al. (2021), as discussed below.

In contrast to acropetal blooming in P. nivea var. nivea and the three related species, the new variety blooms somewhat basipetally. The basipetal blooming is also known in P. ashihoana D.K.Roy, N.Odyuo & N.Tanaka ( Roy et al. 2020: 493) from east India.