Eugenia pachakumachiana Arum. & Murugan, 2022

Murugan, C. & Arumugam, S., 2022, EUGENIA PACHAKUMACHIANA (MYRTACEAE), A NEW SPECIES FROM THE WESTERN GHATS, INDIA, Edinburgh Journal of Botany 79 (1938), pp. 1-10 : 2-5

Eugenia pachakumachiana Arum. & Murugan , sp. nov.

This new species is closely allied to Eugenia rottleriana Wight & Arn. but differs in leaf morphology (oblong-lanceolate versus narrowly oblanceolate), type of inflorescence (simple, solitary versus axillary racemes), flower size (2–3 cm in diameter versus

1–1.5 cm in diameter), calyx lobes (equal, c. 3 mm long, ovate, versus subequal, c. 5 mm long, triangular-ovate), petals (elliptic-ovate versus elliptic-lanceolate), number of ovules (8–12 versus 3–6 in each cell), and fruits (1.5 cm in diameter, exocarp with ridges and furrows [when young] versus c. 1 cm in diameter, exocarp smooth). – Type: India, Tamil Nadu, Theni District, Megamalai Wildlife Sanctuary , Chinnamanur Range , Thenpalani Beat , 09°43′44.0′′N, 77°25′30.6′′E, 990 m, 23 vi 2019, C. Murugan & S. Arumugam 144268 (holotype CAL; isotypes CAL, MH). Figures 1 , 2 .

Tree, 3–6 m high, bark smooth, somewhat flaky, light brown, mottled with light cream to white patches of various sizes, blaze pale red to white; branches terete, tawny, glabrescent; internodes 1–3 cm long; branchlets flat, sparsely brownish pubescent, glabrescent.

Leaves simple, opposite, oblong-lanceolate, 1–7 × 0.8–2 cm, base cuneate, margin entire, revolute, apex obtusely acute or rarely slightly retuse, membranous, dark green and glossy above, pale green beneath with oil glands, young leaves pale pink to reddish; midrib rather prominent; lateral veins indistinct; petioles 4–8 mm long, flat above, rounded below, with brownish adpressed hairs. Flowers axillary, solitary, bisexual, actinomorphic, 2–3 cm in diameter; bracteoles 2, linear, 3–4 mm long, brownish pubescent, rarely persistent; pedicels terete, stout, 1–2 cm long, brownish pubescent. Calyx tube adnate to ovary, turbinate, 2–3

× 2–3 mm, tawny-pubescent; lobes 4, equal, valvate, ovate, c.3 × 3 mm, shorter than petals, curved inwards, apex rounded or obtuse, coriaceous, with adpressed hairs, brownish. Petals 4, alternate to calyx lobes, valvate, elliptic-ovate, 1–1.2 × 0.8–1 cm, flat at base, oblong, entire, apex rounded. Stamens 70–100 in several whorls, unequal, 5–13 mm long; filaments filiform 4–12 mm long; anthers ovate, c. 0.5 mm in diameter, 2-celled, dorsifixed. Disc inconspicuous, flat, 4-angular, pitted, hairy. Ovary inferior, turbinate to globose, c.3 × 3 mm, 2-celled; ovules 8–12 in each locule on axile placentation; style slender, subulate, 1–1.4 cm long; stigma simple, minutely punctiform. Fruits globose, or slightly depressed globose, drupe, c. 1.5 cm in diameter, apex crowned by persistent calyx lobes, dark green when young, pale pink to red when mature, sparsely brown pubescent; exocarp ridged, furrowed when young; seeds 1 or 2, globose, smooth.

Distribution. Known only from Thenpalani Beat, Chinnamanur Range, Megamalai Wildlife Sanctuary, Tamil Nadu, India.

Habitat and ecology. Common along streams in dry deciduous forest from 800 to 1000 m in altitude. The species is ecologically associated with Atalantia racemosa Wight & Arn. , Derris benthamii (Thwaites) Thwaites , Diospyros melanoxylon Roxb. , Erythroxylum lanceolatum (Wight) Walp. , Euonymus dichotomus B.Heyne ex Wall. , Memecylon grande Retz. , Murraya paniculata (L.) Jack, Psydrax dicoccos Gaertn. and Syzygium cumini (L.) Skeels.

Phenology. Flowering and fruiting between May and August.

Etymology. The specific epithet refers to the type locality, Pachakumachi Hills (Megamalai Wildlife Sanctuary), one of the microendemic centres in the Western Ghats of India.

Proposed IUCN conservation category. This species is currently known only from the Megamalai Wildlife Sanctuary. Based on our assessment, it is tentatively classified as Data Deficient (DD) ( IUCN, 2019), because further observations on its occurrence, its distribution and the population size across the entire range of the Western Ghats are essential for assessment of its exact conservation status.

Additional specimens examined. INDIA. Tamil Nadu State: Theni District, Megamalai Wildlife Sanctuary, Chinnamanur Range , Thenpalani Beat , 09°43′44.0′′N, 77°25′30.6′′E, 990 m, 18 viii 2018, C. Murugan & S. Arumugam 138817 (MH) .

The Table summarises the differences between Eugenia pachakumachiana and E. rottleriana .

Figures

Figure 1. Eugenia pachakumachiana Arum. & Murugan, sp. nov. A, Flowering branch; B, fruiting branch; C, calyx, showing disc; D, petals; E, stamen; F, hypanthium with calyx lobes; G, ovary (longitudinal section); H, ovary (cross-section). Drawn from the holotype, Murugan & Arumugam 144268 (CAL), by R. Suresh.

Figure 2. Eugenia pachakumachiana Arum. & Murugan, sp. nov. A, Habit; B, trunk (entire and blazed); C, flowering branch; D, young leaves; E, flowering twig; F, fruiting twig. Photographs: C. Murugan.