Peliosanthes Borah & Taram & Tanaka 2024, sp. nov.
Creators: name: Borah, Dipankar
name: Taram, Momang
name: Tanaka, Noriyuki
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Asparagales
Asparagaceae
Peliosanthes

description: Peliosanthes maheswariana D.Borah, N.Tanaka & Taram, sp. nov.
(Figs 1, 2; Table 1).
Peliosanthes maheswariana sp. nov. is similar to P. sinica F.T.Wang & Tang in having an elongate proximally creeping stem, short anthers and a pistil distally abruptly tapering into a conical style, but differs mainly by the larger leaves with more numerous longitudinal veins, longer peduncle, larger drooping (vs ascending) flowers, internally whitish yellow (vs purple or greenish purple) perianth, larger corona with a relatively narrow distal opening, and almost superior (vs half-inferior) ovary.
TYPE MATERIAL. — India • Arunachal Pradesh, West Kameng district, West Kameng; alt. 800-900 m; 10.I.2023; D. Borah 4045 (holo-, ASSAM!; iso-, ARUN!).
ETYMOLOGY. — The species is named in honor of Shri. Maheswar Borah, a dedicated plant grower of Biswanath, Assam, who has funded the trips of the first author to remote localities of the region in search of plants.
DISTRIBUTION. — NE India (Arunachal Pradesh).
PHENOLOGY. — Flowering in December-February.
HABITAT AND ECOLOGY. — The new species was growing abundantly on rocks or forest floor in the slopes of the type locality above 800 m a.s.l. The area was very close to a perennial stream, but the area remains dry from November to March. It was growing in association with Begonia hatacoa Buch. -Ham. ex D.Don, Dendrocnide sinuata (Blume) Chew, Begonia sp., Pothos sp., Syzygium sp., Psychotria sp., Dalhousiea bracteata (Roxb.) Graham ex Benth., Pseuderanthemum leptanthum (C.B.Clarke) Lindau, etc.
DESCRIPTION
Terrestrial or lithophytic, glabrous evergreen perennial herbs. Stem distally erect to ascending, proximally creeping and rhizome-like, part above ground up to 1 m tall (including leaves on top of stem), proximal creeping part up to 1 m long, terete, up to 0.8 cm in diam., green, annual nodes spaced at intervals of 8-14.5 cm, up to c. 1.8 cm in diam.; scaly leaves (scales) deltoid-ovate, lanceolate, or narrowly deltoid, 1-20 cm long, 0.8-2 cm wide at base (when expanded), acute or acuminate, brownish, hyaline along margins, ephemeral, those sheathing apical portion of stem several, basally imbricate; scars (nodes) of scales between annual nodes 11-15, often with fibrous remnants, spaced at intervals up to 1.7 cm long. Roots 1 to a few (c. 3) from annual nodes aged at least 1 year, wiry, some stilt-like, proximally rigid, up to 3 mm in diam. Leaves 1-2 from annual node, persistent usually for up to 3 years, petiolate; petiole rigid, subterete, 10-30 cm long, 3-5 mm wide, suberect; blade (narrowly) elliptic, 20-40 cm long, 5-10 cm wide, arcuate, base attenuate, margins entire, apex acute to acuminate, sub-plicate, glabrous, glossy on both surfaces, longitudinal veins 64-68 (16-17 thicker and 3 thinner veins within the thicker ones), cross-veinlets fine, inconspicuous, perpendicular to oblique to longitudinal veins, straight to variously curved. Flowering stem (including peduncle and inflorescence rachis) 25-32 cm long, usually slightly declined, flattened and narrowly two-edged; peduncle often slightly curved near base, rigid, up to 17 cm long, 3 mm wide, green; inflorescence a raceme, rachis (6) 9-15 cm long, green, bearing 18- 30 flowers. Bracts (including those on peduncle) antrorse, narrowly triangular to subulate, 4-23 mm long, 1.5-5 mm wide (at base), green or light green, hyaline along margins; sterile bracts on peduncle 2-5 (excluding basal ones); fertile (floral) bracts 2 (1 outer bract and 1 inner bracteole) for each flower, outer bracts exceeding floral buds, inner bracteoles 1-2 mm long, c. 1 mm wide, lanceolate, acuminate. Flowers turned toward the same side, slightly drooping, solitary in bracts, 1.3-1.6 cm across, pedicellate; pedicels terete, 2-3 mm long, straight and ascending when flowers are in bud, becoming curved in flower and in fruit, green, purplish or blackish green. Perianth bowl-shaped, fleshy, externally green to dark purple, glossy, internally whitish yellow, distally 6-cleft; proximal syntepalous part flatly saucer-shaped, 3.5-3.8 mm long, basally abruptly narrowed into a very small stalk much shorter than pedicel; segments obliquely spreading, broadly or deltoid-ovate, 4-6 mm long, 4.5-5 mm wide, apex obtuse to rounded, entire. Stamens 6, monadelphous; corona epitepalous, hemispheric or conoid with wall incurved distally, thickened toward base, wall at base 1.5-1.8 mm thick, basal outline orbicular, 6-7.5 mm in diam. at base, 3 mm high, surface whitish yellow, fleshy, apical opening relatively narrow, rounded, scarcely lobed, 2 mm in diam.; anthers 6, sessile, nearly vertically attached to orifice of corona, ovate, 1.2-1.3 mm long, introrse, creamy; pollen creamy. Pistil 1, 3 mm high, pale green; ovary almost superior (or very slightly half-inferior), hemispheric, 1.5 mm high and 3.5 mm wide at base, trilocular; ovules 4 per locule, borne on basal central placenta; style subconic, truncate at apex, 1.5 mm long, 1-1.5 mm wide at base, stigma trisected, 0.8 mm wide. Immature seeds ovoid-ellipsoid, up to 1.5 cm long, 1 cm wide, green.
TAXONOMIC RELATIONSHIPS
Peliosanthes maheswariana sp. nov. shares a long, proximally creeping stem with six other species so far known. Three of these six species were originally described from SW China; P. sinica, P. pachystachya W.H.Chen & Y.M.Shui (Chen & Shui 2003: 489) and P. minutiflora N.Tanaka, J.Murata & S.K.Wu (Tanaka et al. 2013: 135). The new species is distinguishable from them chiefly by the larger leaf blades with more numerous longitudinal veins, longer peduncle, larger drooping (vs ascending) flowers, internally whitish yellow (vs purple or greenish purple) perianth, larger corona with a relatively narrow distal opening, and almost superior (vs distinctly half-inferior) ovary. The other three of the six species were described from NE India; P. arunachalensis (Roy et al. 2017), P. nagalandensis and P. tobuensis (Odyuo et al. 2020). P.maheswariana sp. nov. differs from P.arunachalensis mainly by the longer leaf blades (20-40 vs 16.5-21.5 cm), longer racemes (6-15 vs 2-3 cm), more numerous flowers (18-30 vs 7-10), and shorter anthers (1.2-1.3 vs 3-3.5 mm); from P. tobuensis by the longer racemes (6-15 vs 2-4 cm), orbicular (vs hexagonal) corona and longer anthers (1.2-1.3 vs 0.3-0.4 mm); from P. nagalandensis by its shorter anthers (1.2-1.3 vs 2-2.5 mm) and almost superior (vs inferior) ovaries. Several selected key distinguishing characters of P. maheswariana sp. nov. and four other related species are compared in Table 1. For the details of differences between the six previously known long-caulescent species and an identification key to them, see Odyuo et al. (2020).
The long, proximally creeping stem of these seven species (including P.maheswariana sp. nov.) is deemed as apomorphic (vs acaulescent or short stem). The species having this trait are hence regarded as members of a monophyletic group. It is highly desirable to conduct a further analysis of their evolutionary relationships.
description: Published as part of Borah, Dipankar, Taram, Momang & Tanaka, Noriyuki, 2024, Peliosanthes maheswariana D. Borah, N. Tanaka & Taram, sp. nov. (Asparagaceae), from Arunachal Pradesh, NE India, and P. sinica new to India, pp. 1-8 in Adansonia (3) (3) 46 (1) on pages 2-4, DOI: 10.5252/adansonia2024v46a1, http://zenodo.org/record/10473197