Peliosanthes hirsuta Averyanov & N.Tanaka, 2017

Nguyen, Khang Sinh, Averyanov, Leonid V., Тanaka, Noriyuki, Konstantinov, Eugene L., Maisak, Tatiana V. & Nguyen, Hiep Tien, 2017, New taxa of Peliosanthes and Tupistra (Asparagaceae) in the flora of Laos and Vietnam and supplemental data for T. patula, Phytotaxa 312 (2), pp. 199-212 : 200-203

Peliosanthes hirsuta Averyanov & N.Tanaka , sp. nov. ( Figs. 1 , 2 ).

Type:— LAOS. Vientiane province, Kasi town area, about 40 km to the north by old road Kasi— Louangphabang, evergreen shady forest on slope of Nam Kean River at lower western slope of Ph. Phaday Mountain at elevation about 700 m a.s.l., 30 November 2014, E. Konstantinov, K-305 (holotype, LE!).

Terrestrial or lithophytic perennial herb. Stem erect or oblique, to (2–)3–4(–5) cm high, covered with many whitish scales that are irregularly imbricate, cuneate, papyraceous and incised. Roots several, rigid, wiry, straight or slightly flexuose, Ø 1.5–2 mm. Leaves proteranthous, petiolate; petiole rigid, often curved or suberect, (3–)4–8(–10) cm long; leaf blade elliptic to broadly elliptic, acute to shortly acuminate, (6–)9–13(–15) cm long, (2.5–)3.5–5.5(–6.5) cm wide, leathery, glabrous, rugulose, often finely undulate along margin, adaxially uniformly dark green and glossy, abaxially light green to whitish green; longitudinal veins (5–)6–9(–11), prominent; secondary transverse veinlets almost invisible. Floriferous stem bearing a terminal raceme; peduncle erect, (3.5–)4–8(–9) cm long, Ø 2.5–3 mm, herbaceous, white, finely ridged longitudinally, hirsutulous to almost glabrous, bracteate; sterile bracts (1–)2–3(–4), loose, ensiform, acuminate, papyraceous, whitish, (1.5–)2–5(–6) cm long, (3–)4–6(–8) mm wide (when flattened for measuring); raceme ovoid, densely many-flowered, (1.5–)2–3.5(–4) cm long, Ø (1.2–)1.5–1.8(–2) cm; rachis thick, straight. Floral bracts 2 per flower, 2-whorled, whitish, scarious to papyraceous, narrowly triangular-ovate, acute, finely ciliate along margin and hirsutulous on abaxial surface, often somewhat descendent, slightly concave to almost flat; outer bract lying below flower, (4–)6–10(–12) mm long, (1.5–)2–3(–3.5) mm wide; inner one (bracteole) lying lateral to flower, elongate, twice smaller, oblique. Flowers solitary on very short, knob-like cylindric pedicel, not widely open, broadly campanulate, (5.5–)6–7(–8) mm across. Perigone adaxially dark dirty brown-purple, distally 6- lobed; proximal syntepalous (tubular) part broadly obconical, 6-ribbed, (2–)2.5–3(–3.5) mm long, (3.8–)4–4.2(–4.4) mm wide, abaxially white, sparsely hirsutulous; segments subsimilar, almost triangular, (2.2–)2.5(–2.7) mm long and broad, blunt to rounded at apex, adaxially thickened medially, abaxially densely hirsute, greenish, rimmed with purple along ciliate margin. Corona slightly convex to almost flat, to 0.5 mm high, obscurely hexagonal, Ø (3.3–)3.5–4(–4.2) mm, apical opening indistinctly hexagonal to irregularly circular, Ø (1.4–)1.6–1.8(–2) mm. Anthers 6, nearly vertically attached to orifice of corona, sessile, ovoid to broadly ovoid, (0.7–)0.8(–1) mm long and wide, introrse, almost black; pollen dull pale yellow. Pistil 1, tricarpellary, dirty purplish, deeper in color distally; carpels hemispheric, distally shortly attenuate into style, adjoining carpels fused at base, at middle and apex closely juxtaposed or loosely connate along ventral sutures, ventral suture of each carpel slightly open in middle portion; ovary almost superior, broadly ovoid to almost globular, 1.4–1.5 mm high and broad; style 0.4–0.5 mm long and wide, deep dirty purple-violet; stigmas narrowly obovate, finely papillose; ovules 4 per locule, borne on basal placentae, narrowly oblong-ovoid.

Etymology:—The specific epithet refers to the hairy state of the perigones, bracts and floriferous stems.

Habitat and phenology:—Primary and secondary broad-leaved evergreen forests on rocky, highly eroded, crystalline limestone at elevation 700–1000 m a.s.l. Terrestrial or lithophytic herb on shady rocky slopes. Flowering in November–December.

Distribution:—Central Laos (Vientiane province, Kasi district). Local endemic to central Laos.

Taxonomic relationships:— Peliosanthes hirsuta is superficially similar to P. argenteostriata Averyanov & Tanaka (2012: 153) occurring in calcareous regions of central and northern Vietnam ( Averyanov & Tanaka 2012). However, it differs by the hairy flowers and the erect or oblique stem without accompanying any markedly developed plagiotropic rhizome. The new species is also unusual in having an almost apocarpous gynoecium. To our knowledge, there has been no report of such a gynoecium and hairy flowers in other members of Peliosanthes , or even of Ophiopogoneae ( Dahlgren et al. 1985, Conran & Tamura 1998) or Ophiopogonoideae ( Takhtajan 2009) including Liriope , Ophiopogon and Peliosanthes .

Additional specimens studied (paratypes):— LAOS. 21 October 2016 and 1 November, L. Averyanov, LA-VN 840a (LE!). Specimen prepared from cultivated plant originally collected in central Laos (Vientiane province, Kasi district, Namken village, Phachao Mountain, around point 19°18’45.5” N 102°22’31.4” E, primary broad-leaved evergreen forest on very steep rocky slopes of mountain composed of highly eroded solid crystalline limestone at elevations 700–1000 m. a.s.l., terrestrial herb on shady place, leaves uniformly dark green and glossy, common, 24 March 2013, L. Averyanov, N.S. Khang, S. Lorphengsy, LA-VN 840).

Figures

FIGURE 1. Peliosanthes hirsuta. A. Flowering plant. B. Inflorescence. C. Portion of rachis with floral bracts subtending a pedicel. D. Flattened floral bract and bracteole. E. Flower, side (left) and frontal (right) view. F. Flowers with flattened tepals, frontal (left) and rear view (right). G. Flower, sagittal section. H. Ovary, view from above. I. Ovary, side views. J. Ovary, transversal section at base (below) and in middle part (above). K, L. Separated singular carpels, adaxial views.All drawn from the type –E. Konstantinov, K-305 by L.Averyanov and T. Maisak.

FIGURE 2. Peliosanthes hirsuta sp. nov. A, B. Flowering plant. C. Inflorescence. D. Flower buds and flowers. E. Flattened plant. F. Inflorescence. G. Rachis with floral bracts (bract and bracteole), flowers removed. H. Bract and bracteole. I. Flowers, side view. J. Flowers, sagittal sections. K. Transversal section of perigone tube with intact ovary, side view (left) and view from above (right). L. Basal portion of flower in transversal section, showing basal portion (left; with ovules) and apical portion (right) of ovary. Photos of E. Konstantinov and L.Averyanov, correction and design by L.Averyanov [A–E—photos from the type E. Konstantinov K-305; F-L—photos from paratype Averyanov et al, LA-VN 840].