Sonerila phuphanensis J. Wai

Wai, Jarearnsak Sae & Hu, Jer-Ming, 2023, Twelve new species of Sonerila (Sonerileae, Melastomataceae) from Thailand, Phytotaxa 620 (2), pp. 107-142 : 127-130

8. Sonerila phuphanensis J. Wai & J.-M. Hu, sp. nov. ( Figures 16 , 17 ).

TYPE:— THAILAND. NORTH-EASTERN: Sakon Nakhon Province, Phu Phan , 17°7’26.36” N, 104°0’58.61” E, 300–400 m, 12 October 2017 , J. Wai 2645 (holotype PSU!, isotypes BKF!, TAI!).

Diagnosis: Sonerila phuphanensis is morphologically most similar to S. deflexa Craib (1928: 140) , but it is distinguished by having narrower leaves (usually narrowly elliptic vs. broadly ovate), cuneate to obtuse leaf bases (vs. cordate) and the absence of long glandular trichomes on the pedicels, hypanthia, petals and capsules (vs. present).

Perennial herbs with tuberous rhizome, 15–30 cm high; rhizome thickened, fleshy, more or less globose, tubercled, 2–3.5 cm in diam.; stems erect or decumbent to ascending, usually unbranched, quadrangular, stout, 3–8 mm thick, fleshy, almost all parts covered with minute brown glandular trichomes (seen under magnification); internodes up to 2.5 cm long. Leaves opposite decussate, isomorphic, light to dark green, brownish or reddish purple, membranaceous when dry; petioles 1.5–7 cm long, slightly winged; blades narrowly elliptic, elliptic-oblong, obovate to oblanceolate, 5–17 × 2.5–10.5 cm, 1.5–3.3 times as long as wide, adaxial surface minutely strigose, abaxial surface subglabrous, few strigose trichomes only present on the secondary veins, apex acute or obtuse, base cuneate or obtuse, margin shallowly serrulate to subentire; venation pinnate; primary vein shallowly grooved above, prominent beneath; secondary veins arising from both sides of primary vein in an alternate or occasionally sub-opposite manner, 2–4 pairs. Inflorescences terminal or axillary, scorpioid cymes, 3–30-flowered, with scattered minute transparent brown glandular trichomes (seen under magnification) on peduncles, pedicels and hypanthia; peduncles 3–10 cm long, erect or slightly curved, green or brownish green; bracts minute, narrowly triangular or oblong-subulate, 0.5–2 mm long. Flowers 3-merous; pedicels 2.5–7.5 mm long, green or purplish. Hypanthium obconical, 5–7 × 2–2.5 mm, purplish or greenish; part of hypanthium free from ovary 2–2.5 mm long. Calyx lobes 3, triangular-ovate, 1–2 × 1.5–2 mm. Petals short-clawed, elliptic-ovate or obovate, 7–11 × 4.5–5 mm, apex acuminate, pinkish, glabrous on both surfaces. Stamens 3, equal, glabrous; filaments 5.5–7 mm long, pinkish; anthers slightly incurved, cordate at base, narrowing towards apex, 4.5– 5.5 mm long, yellow, apex opening with two pores. Ovary 3–4 mm long, 3-locular; ovary crown ca. 1 mm high; ovules numerous; style 11.5–15.5 mm long, pinkish; stigma capitate, papillate. Capsule obconical-pyramidal, 5–7 × 3–4 mm, glabrous. Seeds numerous, triangular ovoid, 0.35–0.45 mm long, 0.2–0.25 mm wide, 0.2 mm thick (measured through SEM), dark brown; testa cells densely verrucose-papillose, with minutely verrucose-papillose tubercles on antiraphal side.

Paratypes:— THAILAND. NORTH-EASTERN: Sakon Nakhon Province, Phu Phan, 17° N, 104° E, 380 m, 13 November 1984, G. Murata et al. T51852 ( KYO!), G. Murata et al. T51963 ( KYO!); ibid., 4 November 1997, P. Puudjaa & T. Chonganurag 442 ( BKF!). Khon Kaen Province, Phu Wieng , 450 m, 16 September 1994, W. Nanakorn et al. 1705 ( QBG!).

Distribution:— Thailand (Sakon Nakhon and Khon Kaen Provinces).

Habitat:— Terrestrial plant. Growing in shaded areas, usually found along the streams in dry deciduous forests, at elevations of 300– 450 m.

Phenology:— Flowering and fruiting were observed from September to November.

DNA barcodes:— OP431324 (ITS), OP453083 (ETS), OP480592 (accD-psal), OP480689 (rpl16), OP503800 (trnS-trnG), OP558289 (ndhC-trnV), OP495603 (ndhF-rpl32). All sequenced from J. Wai 2645.

Etymology:— The specific epithet “phuphanensis” refers to the type locality, Phu Phan Mountains.

Vernacular name:—สาวสนมภูพาน (Sao Sanom Phuphan) ( Thailand).

Proposed IUCN conservation status:— Endangered (EN) under criteria B1ab (iii)+B2ab (iii). This species is known only from two locations in Northeastern Thailand. 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. Since they are particularly attractive to collectors and some populations are very close to the road, they can be affected by human 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 16. Sonerila phuphanensis J. Wai & J.-M. Hu. A. Habit, B. Inflorescence, C. Bracts showing variation, D. Flower, E. Petals showing both adaxial (left) and abaxial (right) surfaces, F. Stamen, G. Longitudinal section of a flower showing hypanthium, stigma, style and ovary, H. Infructescence. All from J. Wai 2645 (PSU). Drawn by K. Singkam.

FIGURE 17. Photos of Sonerila phuphanensis J. Wai & J.-M. Hu. A. Habit and habitat, B. Habit showing leaves, fruiting shoot and tuberous rhizome, C. Inflorescence, D. Flower, E. Seed, lateral view, F. Seed showing verrucose papillae and tubercles on antiraphal side. Photos by J. Sae Wai.