Sonerila banthatensis J. Wai

Wai, Jarearnsak Sae & Hu, Jer-Ming, 2023, Twelve new species of Sonerila (Sonerileae, Melastomataceae) from Thailand, Phytotaxa 620 (2), pp. 107-142 : 112-114

2. Sonerila banthatensis J. Wai & J.-M. Hu, sp. nov. ( Figures 4 , 5 ).

TYPE:— THAILAND. PENINSULAR: Trang Province, Banthat Mountain , 7°26’23.06” N, 99°51’53.89” E, 1265 m, 11 August 2017 , J. Wai 2622 (holotype PSU!, isotypes BKF!, TAI!).

Diagnosis: Sonerila banthatensis is morphologically close to S. bokorensis Cho & Kim (in Cho et al. 2015: 295) in having a caulescent habit, and long stipitate glandular trichomes (ca. 1 mm) on the pedicels and hypanthia, but differs in having a subterranean globose tuber (vs. aggregated tubercles and irregularly shaped rhizomes), creeping to ascending stems (vs. erect), broader leaves (broadly ovate vs. elliptic or narrowly ovate) and larger petals (12–14 × 5–7 mm vs. 9.5–11 × 4–5 mm).

Perennial herbs with subterranean tuber, 5–25 cm high; tuber more or less globose, 5–10 mm in diam.; stems creeping to ascending, simple or few branched, slender, quadrangular, usually elongate, 2–5 mm thick, fleshy, almost all parts covered with minute brown glandular trichomes (seen under magnification), often mixed with long stipitate glandular trichomes ca. 1 mm long; internodes 0.5–2.5 cm long. Leaves opposite decussate, isomorphic, light to dark green or occasionally purplish brown, chartaceous or submembranaceous when dry; petioles 0.5–2.5 cm long, glandular-pilose or glabrescent; blades usually broadly ovate, 1–3.7 × 0.5–2.7 cm, 1.2–2.5 times as long as wide, adaxially sparsely minutely strigose, abaxially sparsely minutely strigose along secondary veins, apex acute to obtuse, base cordate, rounded, or obtuse, margin shallowly serrulate; venation pinnate; primary vein shallowly grooved above, prominent beneath; secondary veins arising from both sides of primary vein in an alternate or sub-opposite manner, 3–4 pairs. Inflorescences usually terminal, scorpioid cymes, 1–9-flowered, with scattered minute transparent brown glandular trichomes on peduncles, pedicels and hypanthia; peduncles erect or slightly curved, 2–10 cm long, green or reddish purple, with long stipitate glandular trichomes or glabrescent; bracts minute, linear-triangular or subulate, 1–1.5 mm long, sometimes with minute trichomes. Flowers 3-merous; pedicels 2.5–4.5 mm long, green or reddish purple. Hypanthium campanulate or obconical, 5–7 × 2.5–3 mm, green or purplish; part of hypanthium free from ovary ca. 2 mm long. Calyx lobes 3, triangular-ovate, 1.5–2 × 2–2.5 mm. Petals short-clawed, elliptic or obovate, 12–14 × 5–7 mm, apex acuminate, pink, adaxially glabrous, abaxially glandular-pilose along the midvein, or occasionally glabrous. Stamens 3, equal, glabrous; filaments 4.5–6 mm long, white or pinkish; anthers slightly incurved, deeply cordate at base, narrowing towards apex, 5–7.5 mm long, yellow, apex opening with two pores. Ovary ca. 3 mm long, 3-locular; ovary crown ca. 1.5 mm high; ovules numerous; style 12–15 mm long, pinkish; stigma capitate, papillate. Capsule obpyramidal, trigonous, 5–6 × 3–4 mm, glabrous or occasionally sparsely pilose. Seeds numerous, narrowly triangular ovoid, 0.6–0.75 mm long, 0.25–0.3 mm wide, 0.2–0.25 mm thick (measured through SEM), dark brown; testa cells densely verrucose-papillose, with minutely verrucose-papillose tubercles on antiraphal side.

Paratypes:— THAILAND. PENINSULAR: Trang Province, Banthat Mountain , 7° 26.4’ N, 99° 51.9’ E, 1240 m, 7 April 2003, D. J. Middleton et al. 2002 ( BKF!). Phattalung Province, Banthat Mountain , 7°26’47.22” N, 99°52’29.75” E, 950‒1250 m, 27 May 2017, J. Satthaphorn s.n. ( BKF!, PSU!, TAI!) .

Distribution:— Thailand (Trang and Phattalung Provinces).

Habitat:— Terrestrial or sometimes epiphytic on tree trunks. Found in both shaded and exposed areas of lower montane forest, at elevations of 950‒1300 m.

Phenology:— Flowering and fruiting were observed from April to August.

DNA barcodes:— OP431332 (ITS), OP453087 (ETS), OP480598 (accD-psal), OP453006 (ndhF), OP480694 (rpl16), OP503805 (trnS-trnG), OP558292 (ndhC-trnV), OP495608 (ndhF-rpl32). All sequenced from J. Wai 2622.

Etymology:— The specific epithet “banthatensis” refers to the type locality, Banthat Mountain.

Vernacular name:—สาวสนมเขาบรรทัด (Sao Sanom Khao Banthat) ( Thailand).

Proposed IUCN conservation status:— Endangered (EN) under criteria B1ab (iii)+B2ab (iii). This species is known only from two locations. The known extent of occurrence (EOO) is less than 5,000 km 2 and the known area of occupancy (AOO) is less than 500 km 2. Although this species is found in protected areas, habitat quality can be affected by tourism activities. Therefore, we qualify this species as EN according to IUCN Red List guidelines Version 15.1 ( IUCN Standards and Petitions Committee 2022).

Figures

FIGURE 4. Sonerila banthatensis J. Wai & J.-M. Hu. A. Habit, B. Leaf showing both adaxial (left) and abaxial (right) surfaces, C. Inflorescences, glabrous (left), with trichomes (right), D. Bracts, E. Petals showing both surfaces, glabrous (left), with glandular trichomes on abaxial surface (right), F. Stamens, side view (left), front view (right), G. Longitudinal section of glabrous and hairy flowers showing hypanthium, stigma, style and ovary.All from J. Wai 2622 (PSU). Drawn by K. Singkam.

FIGURE 5. Photos of Sonerila banthatensis J. Wai & J.-M. Hu. A. Habit and habitat, B. Upper portion of stems showing glandular trichomes, C. Leaves showing both adaxial (left) and abaxial (right) surfaces, D. Inflorescence, E. Seed, lateral view, F. Seed showing verrucose papillae and tubercles on antiraphal side. Photos by J. Sae Wai.