Peliosanthes ligniradicis N.Tanaka, M.Taram & D.Borah, 2020

Taram, Momang, Borah, Dipankar & Tanaka, Noriyuki, 2020, Peliosanthes ligniradicis, a new species (Asparagaceae) from Arunachal Pradesh, NE India, Phytotaxa 438 (1), pp. 43-48 : 44-47

Peliosanthes ligniradicis N.Tanaka, M.Taram & D.Borah sp.nov. ( Figs.1 , 2 ).

Similar to P. subspicata N.Tanaka , but differs by the thicker semi-woody roots, somewhat elongate stem, shorter leaf blades and petioles, ovate-oblong or oblong perianth segments, and obpatelliform corona basally hexagonal apically 6-crenate.

Type:― INDIA. Arunachal Pradesh. East Siang District: Pasighat, 28°3´6´´N, 95°19´14´´E, above 400 m a.s.l., 16 November 2018. Momang Taram & Dipankar Borah 431 (holotype ASSAM, isotype ARUN).

Terrestrial evergreen perennial herbs. Stem rhizome-like, up to 10 cm long, 1 cm in diam., unbranched, (sub) moniliform, intervals between knobs up to 2 cm long, part above ground usually erect, 1.5–3 cm tall, covered with several loose papyraceous scales, internodes between scales 1–3 mm long. Roots many, wiry, some stilt-like, rigid, semi-woody, up to 5 mm in diam. Leaves 1–3 per annual node, erect, petiolate; petiole rigid, subterete, 13–20 cm long, 3–4 mm wide; blade (narrowly) elliptic, 18–25 cm long, 5–6 cm wide, base decurring into a petiole, margin entire, apex acute to acuminate, glabrous, transverse veinlets sub-perpendicular to many longitudinal veins (12 thicker and 14 thinner). Flowering stem (including peduncle and inflorescence rachis) up to 8–25 cm tall; peduncle erect, rigid, 3–5 cm long, 2–4 mm wide, purplish; inflorescence a raceme, rachis 5–18 cm long, green, purplish green or purple, bearing densely arranged 24–60 flowers. Floral bracts (including those subtending undeveloped floral buds in the lower part of the inflorescence) green or light green with hyaline base, linear-lanceolate, subulate or linear, 8–15 mm long, 1–2 mm wide, exceeding flowers; inner bracts (bracteoles) sometimes lacking, but when present, 3–5 mm long, 1 mm wide. Flowers solitary in bracts, nodding, articulated with a purplish pedicel 3–4 mm long. Perianth fleshy, purplish green, proximal syntepalous part obconic, distally 6-cleft; segments obliquely spreading, somewhat incurved, laterally slightly revolute, ovate oblong to oblong, 3–4 mm long, 2 mm wide, apex obtuse to rounded, very minutely and irregularly denticulate. Androecium monadelphous; corona obpatelliform with wall narrowing distally, hexagonal and thickened toward base, 1 mm tall, 3–4 mm in diam., apical opening 6-crenate, 1–1.5 mm in diam; anthers 6, nearly vertically attached to orifice of corona, sessile, oblong, less than 0.5 mm long, introrse, almost black. Pistil 1, halfinferior; ovary conical, (sub) hexagonal at base, 2 mm tall and wide, trilocular; ovules usually 4, arising from base of central axis of ovary; style conical, tapering distally, less than 2 mm tall, trigonous; stigma tri-dissected, ridged, purple. Immature berry-like seeds oval, 1–1.5 cm long, 0.5–0.8 cm across, greenish, seed core ellipsoid.

Additional specimen examined (paratype):― INDIA. Arunachal Pradesh: East Siang District, Pasighat, 28°3´9´´N, 95°19´18´´E, above 400 m a.s.l., 23 November 2019. Momang Taram & Dipankar Borah 651 (ASSAM).

Distribution:―NE India. Known only from the type locality. Only one population of more than 100 individuals observed so far from East Siang district of Arunachal Pradesh was small with scattered distribution, covering an area of 2 km 2.

Habitat:―It grows on litter beds in slopes of stream sides. It is an element of humid tropical forests at elevations above 400 m. The associated plants are Trevesia palmata (Roxb. ex Lindl.) Vis. , Actephila excelsa (Dalzell) Müll.Arg. , Alocasia acuminata Schott , Urtica sp. , Dalhousiea bracteata (Roxb.) Graham ex Benth. , Chukrasia sp. , Strobilanthes elongate C.B.Clarke. Nearly 100 individuals of the new species were found in the habitat.

Phenology:―Flowering from September to December; fruiting from December to February.

Etymology:―The species epithet is named after the thick, semi-woody roots.

Taxonomic relationships:―Seven species have so far been recognized from NE India ( Hooker, 1892, Hara et al. 1978, Roy et al. 2017a, Tanaka 2018): P. griffithii , P. macrophylla Wall. ex Baker (1879: 505) , P. macrostegia , P. arunachalensis Roy, Mao & Averyanov (2017b: 15) , P. khasiana , P. subspicata , and P. pumila . The new species here described is somewhat similar to P. subspicata in having a relatively short peduncle and long spike of shortly pedicellate drooping flowers, but is clearly distinguished from it by the thicker, stilt-like, semi-woody roots, shortly elongate (vs. hardly elongate), moniliform rhizome-like stem, shorter (13–20 vs. 25–50 cm long) petiole, shorter (18–25 vs. 23–31 cm long) leaf blades, ovate oblong to oblong (vs. ovate, broadly ovate or sub-orbicular) perianth segments, and basally hexagonal (vs. orbicular), obpatelliform (vs. distally annular), apically 6-crenate (vs. entire) corona. Flowers of P. subspicata based on the specimen P00214606 are depicted in figure 6 (P00214606 is erroneously cited as P00214609) in Tanaka (2018: 43). A more detailed comparison of several key characters between the two species is presented in Table 1.

Roots Roots often stilt-like, semi-woody, up to 5 mm in diam. Roots cordlike, up to 2 mm in diam.

Leaves Petiole 13–20 cm, blade 18–25 cm long, Petiole 25–50 cm, blade 23–31 cm long.

Flowering stem * Erect, up to 8–25 cm tall; Sub-erect or ascending, 14–39 cm.

Pedicel 3–4 mm long. 0.5–2.5 mm long,

Perianth Obconic; segments somewhat incurved, laterally Broadly obconic or crateriform; segments obliquely slightly revolute, ovate oblong to oblong, 3–4 expanded, ovate, broadly ovate or sub-orbicular, mm long, 2 mm wide, margins very minutely and 1.7–4 mm long, 2–4.5 mm wide, proximally imbricate, irregularly denticulate, apex obtuse to rounded. margins minutely (denticulate-)-erose, apex rotund or obtuse.

Corona Hexagonal, obpatelliform with wall narrowing distally, Orbicular at base, distally abruptly raised at periphery of apex 6-crenate, orifice 1.5 mm in diam. central orifice, apex entire, orifice 1.5–2.5 mm in diam.

Stamens Oblong, less than 0.5 mm long Ovoid, 0.7–1.5 mm long,

Ovary Conical, 2 mm tall, ovules usually 4 Sub-conic, 1.5–2 mm tall, ovules up to 5 per locule

Seeds Oval Ellipsoid or ovoid

Distribution NE India, Arunachal Pradesh NE Bangladesh (Silhet). NE India (Khasia)

1 More than 5 individuals from the type locality were examined; 2 at least 13 individuals on 10 herbarium sheets cited in Tanaka (2018) were examined; * = including peduncle and inflorescence rachis.

Figures

FIGURE 1. Peliosanthes ligniradicis. A. A plant in its habitat. B. A plant with flowers C. A plant with fruits. D. A plant under cultivation with elongate rhizome-like stem, thick descending roots and young leaf.

FIGURE 2. Peliosanthes ligniradicis under cultivation. A. Flowering plant. B and C. Venation of leaf blade: adaxial (B) and abaxial (C). D. Detail of inflorescence. E. Fertile bract. F–K. Flowers: F. Front view. G. Side view slightly from below. H. Side view slightly from above. I. Longitudinal section. J. Corona with six anthers and upper part of pistil; perianth segments removed. K. Cross section of ovary.