Osbeckia yercaudensis Saravanan & Kaliamoorthy, 2023

Saravanan, Thokuluva Santharam & Kaliamoorthy, Seventhilingam, 2023, Osbeckia yercaudensis (Melastomataceae) a new species from the Eastern Ghats, India, Phytotaxa 583 (3), pp. 292-296 : 292-295

Osbeckia yercaudensis Saravanan & Kaliamoorthy , sp. nov. ( Figure 1 )

Osbeckia yercaudensis is morphologically close to Osbeckia mehrana Giri & Nayar and Osbeckia wightiana Bentham ex Wight & Arnott in being perennial woody shrubs with ovate lamina and bracts, pentamerous flowers, campanulate hypanthium and capsule, obovate, pink to purple petals. However, Osbeckia yercaudensis differs from O. mehrana in its height (up to 60 cm tall vs 3 m tall), size of the leaves (0.9–2.4 × 0.6–1.6 cm vs 1.5–4.6 × 0.8–3.0 cm), inflorescence (2–3-flowered terminal cymes vs 5–7-flowered terminal or axillary panicles), sepals (oblong to slightly falcate, irregularly emarginate apex vs triangular, acute apex), style (2.1 cm long vs 1.2–1.7 cm long) and seeds (cochleate or U shaped, minutely toothed vs curved, muricate). It also shows similarities with O. wightiana , but differs by its height (up to 60 cm tall vs up to 3 m tall), size of the leaves (0.9–2.4 × 0.6–1.6 cm vs 3.1–7.1 × 2.1–3.5 cm), inflorescence (2–3-flowered terminal cymes vs 3–7-flowered terminal cymes), sepals (oblong to slightly falcate, apex with long white hairs vs subulate, apex with stellate emergences), style (2.1 cm long vs 1.1–1.5 cm long), and seeds (cochleate or U shaped vs curved) ( Table 1 ).

Type:— INDIA. Tamil Nadu: Salem District , Yercaud, Shevaroy Hills, MALCO mines, 11º49’17”N, 78º13’29”E, 1350–1540 m, 20 December 2021, Saravanan & Kaliamoorthy 136010 (holotype MH!; isotypes MH!) .

Erect, perennial shrubs, up to 60 cm tall. Stems woody, branched, sub-quadrangular, densely covered with patent, long, ascending brown hairs in younger branches, greenish; mature branches glabrous due to hairs falling off, brownish. Leaves simple, opposite, petiolate, greenish when young, brownish at maturity; lamina ovate, acute at apex, obtuse at base, 0.9–2.4 × 0.6–1.6 cm, margins ciliate, 5-nerved (prominent beneath), both surfaces densely covered with ascending to patent, thin, long hairs (0.3 cm long); petioles 0.6 cm long, densely covered with long ascending hairs. Inflorescence 2–3-flowered terminal cymes, subtended by a pair of leaves. Flowers pentamerous, pedicellate; bracts broadly ovate, acute at apex, obtuse at base, 0.8 × 0.9 cm, margins ciliate, dorsally covered with long ascending hairs; pedicels 0.7 cm long, densely covered with ascending to patent, thin, long hairs. Hypanthium 1.2 cm length × 1.5 cm diameter, campanulate, densely covered with stellate, stalked emergences; intersepalar emergences 0.3 cm long, stalked, stalk terete with many patent long hairs, head disc-like with stellate long patent hairs, persistent in fruits. Sepals oblong to slightly falcate, apex irregularly emarginate with a tuft of long hairs, base truncate, 0.7 × 0.3 cm, margins ciliate, prominently 1-nerved with many patent hairs confined to nerves on dorsal surface. Petals obovate, 2.8 × 2.5 cm, pink to purple, margins ciliate, caducous. Stamens 10, equal; filaments 1.1 cm long, pale yellow, glabrous; anthers 0.9 cm long, narrowly ovate to oblong, twisted, pore oblique on ventral side at the apex, yellow; connective prolonged into a small, indistinctly lobed collar. Ovary 5-locular, adnate to hypanthium for about half of the length, 0.9 cm long, densely covered with long white hairs; style 2.1 cm long, glabrous, slightly curved; stigma green, capitate, papillose. Capsules 1.1 × 1.0 cm, campanulate; seeds 0.1 cm long, numerous, cochleate or U shaped, margins minutely toothed, pale straw-coloured when young, blackish at maturity.

Phenology:—Flowering & fruiting: September–February.

Ecology:—Occurs at borders of semi evergreen forests and in rock crevices, in association with Alstonia venenata Brown (1810: 64) , Bauhinia purpurea Linnaeus (1753: 375) , Crotalaria longipes Wight &Arnott (1834a: 183) , Psydrax dicoccos Gaertner (1788: 125) , Solanum myriacanthum Dunal (1813: 218) etc., between 1350–1540 m elevation.

Conservation Status:— Osbeckia yercaudensis is only known from the type locality with about 15–20 individuals in an area of about 1 km 2. However, the present habitat is prone to forest fires and faces threats from grazing, mining and other anthropogenic factors. Due to its rarity and threats to the habitat, the species falls under the category Critically Endangered ( CR B1 ab (i, ii, v); 2ab (i, ii, iv); D) in accordance with the IUCN guidelines ( IUCN 2019) .

Etymology:—The species is named after the type locality, Yercaud, Salem District in Tamil Nadu, India.

Figures

FIGURE 1. Osbeckia yercaudensis Saravanan & Kaliamoorthy, sp.nov. A. Habit; B & C. Adaxial and abaxial surfaces of leaves respectively; D. Top view of a flower; E. Hypanthium; F. Bract; G & H. Dorsal and ventral views of sepals respectively; I. Petal; J. Intersepalar emergence; K.Androecium; L. Gynoecium; M. Seeds. (Photographs by T.S. Saravanan).