Peliosanthes epigynica N.Tanaka, Aver. & V.C.Nguyen, 2024

Averyanov, Leonid V., Tanaka, Noriyuki, Nguyen, Van Canh, Maisak, Tatiana V. & Shvanova, Valeria V., 2024, Peliosanthes epigynica (Asparagaceae, Convallarioideae), a new species from southeastern Vietnam, Phytotaxa 668 (2), pp. 195-200 : 196-198

Peliosanthes epigynica N.Tanaka, Aver. & V.C.Nguyen , sp. nov. ( Fig. 1 )

Diagnosis: —Differs from any other Peliosanthes by a combination of the following character states: comparatively small (up to 16× 5.5 cm) elliptic leaf blades, small (up to 6.4 mm high, 6.2 mm across) cernuous narrowly campanulate purple/violet flowers, and a nearly flat-topped, completely inferior ovary with a comparatively short (up to 0.7 mm) straight (non-tortuous) conoid style.

Type: — VIETNAM. Ninh Thuan Province: Ninh Hai District, Vinh Hy Townlet , very dry evergreen primary and secondary short to tall windformed coastal forest on very steep sea-faced sandstone rocky slopes at elevation of 200–250 m a.s.l., terrestrial herb in shady rocky places, flowers dark violet, not common, 16 May 2024, L. Averyanov, V. C. Nguyen, T. Maisak, AL3235 (holotype: LE LE01276231 ! https://en.herbariumle.ru/?t=occ&id=229827; isotype: LE LE01276232 ! https://en.herbariumle.ru/?t=occ&id=229828. Photos of the plant used for preparation of the type specimens ( LE LE01255093 https://en.herbariumle.ru/?t=occ&id=228130).

Etymology: —The specific epithet refers to the epigyny of the flowers which distinguishes the new species from many other species of the genus.

Description:—Plant herbaceous, terrestrial, rhizomatous, almost acaulescent, evergreen, perennial. Rhizome plagiotropic, horizontal to ascending, simple or few branching, (1)1.5–2.5(3) cm long, (4.5)5–6(7) mm in diameter, covered with few remnants of papyraceous pale gray bracts, producing several thick fleshy light gray to almost white roots. Stem ascending or erect, less than 1 cm high, at anthesis loosely covered with few remnants of herbaceous pale gray brownish bracts, bearing (4)5–6(7) leaves. Leaves petiolate, much exceeding flowering stems; petiole erect, straight or slightly arcuate, (8)10–15(12) cm long, rigid, stout, shallowly channeled adaxially; leaf blade narrowly elliptic to elliptic, acute to shortly acuminate at apex, (8)12–15(16) cm long, (2.5)3–5(5.5) cm wide, often crisped (wavy) along margins, leathery, rigid, glabrous, glossy, dark green above, light green beneath, with many longitudinal veins (11–21 veins in middle part); secondary transverse veinlets numerous, distinct, oblique to perpendicular to longitudinal veins. Flowering stem (peduncle and inflorescence) (10)11–15(16) cm long; peduncle ascending to erect, (6.5)7–9(10) cm long, 2–2.5 mm in diameter, greenish to dull violet, stout; sterile bracts on peduncle 4–8, narrowly triangular ovate, (2.5)3.5–5(6) mm long, 2–2.5 mm wide, acute to acuminate, light greenish; inflorescence a reduced subdense thyrse of many flowers, rachis (3.5)4–6(7) cm long, nearly as long as or shorter than the peduncle. Floral bracts 2 (outer bract 1 and inner bracteole 1) at base of pedicel, narrowly triangular to lanceolate, acute at apex, light green to pale violet, somewhat scarious; bract (3.5)4–5(5.5) mm long, (0.8)1(1.2) mm wide, descending to horizontal, little shorter than open flower; bracteole borne often at right angle to bract, twice smaller than bract. Flowers blooming acropetally to almost simultaneously, solitary in axils of bracts, campanulate, not widely opening, (5)6.2(6.4) mm high, (5.8)6(6.2) mm wide. Pedicel cylindric, somewhat curved downward, light green, (1)1.1–1.2(1.3) mm long. Perianth distally 6-cleft, fleshy; basal syntepalous part broadly obconoid, 2.8–3 mm high, 3.8–4 mm in diameter at apex, pale greenish to purple violet; perianth lobes 6 in 2 whorls of 3, triangular broadly ovate to ovate, (2.8)3–3.2(3.4) mm long, (2.6)2.8–3(3.2) mm wide, obtuse to roundish at apex, slightly imbricate proximally, abaxially pale greenish to purple violet, dark violet along margins, adaxially dark violet to almost black. Androecium of 6 stamens monadelphous, forming a corona; corona slightly convex, dull purple violet to dark violet, 0.5–0.6 mm high, (2.8)3(3.2) mm in diameter, almost orbicular in basal outline; apical opening circular to obscurely hexagonal, 1.1–1.3 mm in diameter. Anthers 6, attached to distal inner side of corona wall, sessile, introrse, ovoid, 0.5–0.6 mm long, about 0.4 mm wide, dark violet to black; pollen white to light yellowish. Pistil 1; ovary perfectly inferior, obconoid, nearly flat (truncate) at apex (except the narrow furrow immediately around base of style), about 2.2 mm across, 3-loculate, each locule containing 2–3 ovules on central basal placentae; style conoid, olive green to violet, 0.6–0.7 mm tall, 0.5–0.6 mm wide near the base; stigma 3-lobed. Fruits unknown.

Ecology and phenology: —Occurs in shady rocky places in a very dry coastal evergreen forest on very steep sandstone slopes facing the ocean at elevations of 200–250 m a.s.l. Flowering in May.

Conservation status: —Only a few mature individuals were found in the type locality. With no detailed information on the occurrence, the conservation status of the new species is assessed here as “Data Deficient” (DD), following the guidelines of IUCN (2024).

Distribution: — Vietnam, Ninh Thuan Province (Ninh Hai District). Known only from a single location in low hills near Vinh Hy Townlet.

Taxonomic relationships: —Currently we hardly find any other species closely related to Peliosanthes epigynica . It is a remarkable trait that the new species possesses a nearly flat-topped (truncate), perfectly inferior ovary, as this trait is shared by only several species in this genus. The new species is distinguishable from any of them by differences in other characters. For example, from P. cumberlegii Larsen (1966: 198) from Thailand, P. epigynica differs by the drooping (vs. antrorse), less widely open flowers. Peliosanthes weberi (L.Rodr.) Tanaka (2004: 362) , which was originally referred to Neolourya Rodriguez (1934: 96) , shares a perfectly inferior ovary with P. triandra Aver & N.Tanaka in Averyanov et al. (2014: 18), P. choriandra Aver., N.Tanaka & K.S.Nguyen in Averyanov et al. (2017: 699) and P. thachii Luu, X.B. Nguyen-Le & H.C.Nguyen in Luu et al. (2024: 171). Peliosathes epigynica is distinct from all of them chiefly in the purple/violet (vs. green) flowers with a shorter conoid straight (vs. slender tortuous) style. The new species is also distinguishable from P. hypogyna from Thailand (the flower of this species is actually not hypogynous but epigynous, as described in the protologue) chiefly by its smaller leaf blades (up to 16×5.5 vs. ca. 20× 6.9 cm) and purple/violet (vs. pale greenish white) flowers; from P. nagalandensis Odyuo, D.K.Roy, N.Tanaka & A.A.Mao in Odyuo et al. (2020: 286), which is indigenous to NE India, by the smaller (5.8–6.2 vs. 15–20 mm in diameter) less expanded flowers, basally circular (vs. hexagonal) corona, shorter style (0.6–0.7 vs. 1.5–2 mm) and shorter anthers (0.5–0.6 vs. 2–2.5 mm); and from P. linearifolia Kroupsky, N.Tanaka, K.S.Nguyen & Nuraliev in Kroupsky et al. (2023: 96) from southern Vietnam in the estoloniferous (vs. stoloniform) rhizome, elliptic (vs. linear/ ensiform) leaf blades, basally circular (vs. hexagonal) corona with an almost entire (vs. 6-dentate) distal orifice.

Figures

FIGURE 1. Peliosanthes epigynica. A. Flowering plant in natural habitat. B. Whole flowering plant (slightly flattened) and detached flowering stem. These were later employed as partial constituents of holotype. C–E. Inflorescences. F, G. Portion of inflorescence. H. Flower on rachis, front view. I–K. Detached two flowers, front (I), side (J), and rear (K) view. L. Flower, sagittal section. M. Ovary and corona, sagittal section. N. Corona, view from above (left) and below (right). Photos, photo correction and design by L. Averyanov and T. Maisak.