Strobilanthes medahinnensis Nilanthi, 2021

Nilanthi, Rajapakse Mudiyanselage Renuka, Samarakoon, Hiruna, Jayawardana, Nuwan, Wijesundara, Siril & Bandaranayake, Pradeepa Chandani Gunathilake, 2021, Strobilanthes medahinnensis (Acanthaceae) a new species, based on morphological and molecular data, from the Peak Wilderness Nature Reserve, Sri Lanka, Phytotaxa 514 (1), pp. 26-38 : 33-36

Strobilanthes medahinnensis Nilanthi , sp. nov. ( Figure 6 & 7 )

Type:— SRI LANKA, Sabaragamuwa Province, Ratnapura District, Peak Wilderness Nature Reserve , Medahinna, E 166892, N 179540, 1430 m, 29 June 2020, Nilanthi 149 (holotype PDA!) .

Diagnosis:— The new species is similar to Strobilanthes anceps , but differs by shrubs with less branched (not much branched), rounded stem (not quandrangular), leaves with acuminate apex (not long acuminate or caudate), elongated spikes (not short spikes), lanceolate outermost bracts (not ovate), outermost bract with long acuminate apex (not acute), outermost bract with long purplish-brown stalk (not short green stalk), inner bracr with purplish-brown outer surface (not green outer surface), androecium with glabrous filaments (not pubescent filaments), dark brown anther thecae (not white anther thecae), glabrous style (not hairy style), glabrous ovary (not hairy ovary).

Description:— Shrub, 1.0– 1.5 m high. Stem erect, rounded, swollen just above the nodes, brownish green below, purplish-brown above, villous, internodes 2.5–5.0 cm long. Leaves opposite, slightly unequal; petiole 4.0–6.0 cm long, villous, blades ovate, 3.0–12.0 × 1.5–2.0 cm, base rounded, margin ciliate, apex acuminate, indumentum granular adaxially, abaxial less pubescent, midvein densely villous, few yellow gland dots present abaxially, lateral nerves 5-8 pairs, prominent on both surfaces, raised beneath. Inflorescence bifurcate or trifurcate in axillary and terminal pedunculate spikes, 3.5–6.5 cm long, 1 cm wide, peduncle purplish-brown. Outermost bracts lanceolate, 2.0–3.0 × 0.6–0.8 cm, base cuneate, margin ciliate, apex acuminate, 4.5–5.8 mm long stalked, midrib prominent; Inner bracts obovate, 1.2–1.5 × 0.4–0.6 cm, outer surface purplish-brown, recurved, gland-dotted dorsally, ciliate on the margins; bractioles linear-oblong, narrowly acute 6.0– 0.9 mm long, ciliate, narrowly acute at apex, slightly shorter than the calyx, outer surface purplish-brown. Calyx 6-9 mm long, 5-lobed to the base, the lobes equal, linear-lanceolate, ciliate on margins, acute at apex, outer surface purplish-brown. Corolla 2.1–2.4 cm long, pale pinkish white, dark purple lines on inner surface of corollainner side pubescent, corolla gradually expanded from the base, lobes ovate, ca. 2.5 mm long, ca. 4 mm wide, apex obtuse. Stamens 4, included, didynamous, basally attached to corolla tube, filaments of shorter pair 8.0– 8.5 mm long, longer pair 12.0– 12.5 mm long, anthers dark brown. Ovary ovate-oblong, 2 mm long, glabrous; style slender; stigma simple. Capsule unseen.

Etymology:— The specific epithet “ medahinnensis ” refers to the type locality.

Phenology:— It was in flowering from June to August.

Habitat and Distribution:— This species inhabits at Medahinna growing in the shade and along the nature trail of Erathna in an evergreen rain forest at an elevation of 1400–1500 m in a wet zone. This area belongs to the Peak Wilderness Nature Reserve where many endemic species of flowering plants were recorded, and it is legally administered by the Department of Wildlife Conservation. The allied species S. anceps , which has a wide distribution in Sri Lanka, is also mostly found in montane forests at around 1450–2300 m altitudes.

Conservation status:— The new species was only discovered at Medahinna from the Peak Wilderness Nature Reserve in Sri Lanka. About 50 individuals were observed and the extent of occurrence was ca. 1 km 2. Further explorations to obtain the precise population status are needed to assess its conservation status. Based on available data, the new species is assigned to the category ‘Data Deficient’ (DD) of the International Union for Conservation of Nature ( IUCN, 2019).

Figures

FIGURE 6. Strobilanthes medahinnensis. A. Flowering branch; B. Inflorescence; C. Leaf D. Inner bract; E: Half flower; F. Calyx; G. Stamens; H. Outermost bract; I. Close up of the leaf surfaces adaxial and abaxial. (Drawn by Rukmal Ratnayake on the holotype).

FIGURE 7. Strobilanthes medahinnensis. A-B. Habit; C. Stem; D. Front view of the corolla; E–H. Inflorescence; F. Leaf (adaxial); G. Half flower; I. Leaf (abaxial); J. Inner bract; K. Outermost bract; L. Calyx with Bractiole.