Sonerila phuhinrongklaensis J. Wai

Wai, Jarearnsak Sae & Hu, Jer-Ming, 2023, Twelve new species of Sonerila (Sonerileae, Melastomataceae) from Thailand, Phytotaxa 620 (2), pp. 107-142 : 125-127

7. Sonerila phuhinrongklaensis J. Wai & J.-M. Hu, sp. nov. ( Figures 14 , 15 )

TYPE:— THAILAND. NORTHERN: Phitsanulok Province, Nakhon Thai District, Phu Hin Rong Kla , P. Kamol 2020–1 (holotype PSU!, isotype BKF!) .

Diagnosis: Sonerila phuhinrongklaensis is morphologically most similar to S. secunda Brown (in Bennett 1844: 216) in having a tuberous rhizome, often variegated leaves and funnel-shaped capsules, but differs by its subglabrous petioles (vs. long woolly, trichomes 2–3 mm long), spreading calyx lobes in immature fruits (vs. erect) and long stipitate glandular trichomes on peduncles and pedicels (trichomes ca. 0.5 mm long vs. absent).

Perennial herbs with subterranean rhizhome, 5–30 cm high; rhizome globose or irregularly shaped, 5–20 mm in diam.; stems erect or ascending, usually unbranched, quadrangular, 2–5 mm thick, fleshy, almost all parts covered with minute brown glandular trichomes (seen under magnification); internodes up to 4 cm long. Leaves opposite decussate, isomorphic, light to dark green, brownish or reddish purple, often with scattered numerous white spots, membranaceous when dry; petioles 0.5–5 cm long, subglabrous; blades ovate, elliptic, or lanceolate, 3–13 × 1.5–7.5 cm, 1.44–3 times as long as wide, adaxial surface minutely strigose, abaxial surface sparsely strigose, trichomes usually present on the secondary veins, apex acute, obtuse or acuminate, base rounded, cordate or broadly cuneate, margin shallowly serrulate; venation pinnate; primary vein shallowly grooved above, prominent beneath, sparsely strigose; secondary veins arising from both sides of primary vein in an alternate or occasionally sub-opposite manner, 3–5 pairs. Inflorescences terminal or axillary, scorpioid cymes, 1–20-flowered, with scattered minute transparent brown glandular trichomes (seen under magnification) mixed with scattered long stipitate glandular trichomes on peduncles (trichomes ca. 0.5 mm long), pedicels and hypanthia; peduncles 2–7 cm long, erect or slightly curved, greenish or purplish; bracts minute, narrowly triangular or subulate, ca. 0.5 mm long. Flowers 3-merous; pedicels 3.5–6 mm long, purplish. Hypanthium cylindrical or obconical, 7–7.5 × 2–2.5 mm, purplish or greenish, sparsely glandular pilose; part of hypanthium free from ovary 2–3 mm long. Calyx lobes 3, triangular-ovate, 1–1.5 × ca. 2 mm, obviously spreading in immature fruits. Petals short-clawed, elliptic or obovate, 8–13.5 × 4–6 mm, apex acuminate, pinkish, adaxial surface glabrous, abaxial surface with glandular trichomes along the midvein (trichomes ca. 0.5 mm long). Stamens 3, equal, glabrous; filaments 6–8 mm long, pinkish white; anthers slightly incurved, cordate at base, narrowing towards apex, 6.5–8 mm long, yellow, apex opening with two pores. Ovary 4–4.5 mm long, 3-locular; ovary crown ca. 1 mm high; ovules numerous; style 11–15 mm long, pinkish; stigma capitate, papillate. Capsule obconical or funnel-shaped, 5–7.5 × 3–4 mm, subglabrous. Seeds numerous, triangular ovoid, 0.3–0.35 mm long, 0.2–0.25 mm wide, ca. 0.2 mm thick (measured through SEM), dark brown to nearly black; testa cells densely verrucose-papillose, with minutely verrucose-papillose tubercles on antiraphal side.

Paratypes:— THAILAND. NORTHERN: Phitsanulok Province, Nakhon Thai District , Phu Hin Rong Kla, 1300 m, 14 October 1998, P. Suksathan 1288 ( QBG); ibid., 29 October 2001, S. Watthana & P. Suksathan 1563 ( QBG); ibid., 1200 m, 17 October 2015, M. Poopath et al. 1325 ( BKF!); ibid., Sapan Morana, 20 October 2016, J. Wai 2556 ( PSU!); ibid., Saifon Waterfall, 20 October 2016, J. Wai 2557 ( BKF!, PSU!, TAI!); ibid., Lan Hin Pum , 20 October 2016, J. Wai 2558 ( PSU!, TAI!); ibid., Air-raid shelter, 20 October 2016, J. Wai 2560 ( PSU!); ibid., 25 December 2016, J. Wai 2609 ( PSU!). NORTH-EASTERN: Phetchabun Province, Khao Kho, Sridith Waterfall , 16°37’46.89” N, 100°56’23.05” E, 700 m, 15 December 2021, J. Wai 2769 ( BKF!, PSU!, TAI!). Loei Province, Phu Ruea District, Phu Ruea , 1150–1530 m, 24 December 1982, H. Koyama et al. T31607 ( KYO!); ibid., Hin Sam Chan Waterfall , 17°30’00” N, 101°20’09” E, 1141 m, 4 November 2014, M. Poopath et al. 855 ( BKF!); ibid., 18 October 2016, J. Wai 2554 ( BKF!, PSU!, TAI!); ibid., 9 October 2017, J. Wai 2643 ( PSU!, TAI!) .

Distribution:— Thailand (Phitsanulok, Phetchabun and Loei Provinces).

Habitat:— Terrestrial plant.This species was often found growing in shaded areas, along the stream in submontane to montane forests, at elevations of 700–1550 m.

Phenology:— Flowering and fruiting were observed from October to December.

DNA barcodes:— OP431251 (ITS), OP453054 (ETS), OP480538 (accD-psal), OP452976 (ndhF), OP480664 (rpl16), OP503771 (trnS-trnG), OP558261 (ndhC-trnV), OP495573 (ndhF-rpl32). All sequenced from J. Wai 2609.

Etymology:— The specific epithet “phuhinrongklaensis” refers to the type locality, Phu Hin Rong Kla.

Vernacular name:—สาวน้ำตกภูหิน (Sao Namtok Phu Hin) ( Thailand).

Proposed IUCN conservation status:— Endangered (EN) under criteria B1ab (iii)+B2ab (iii). This species is known only from three locations in Northern and 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 tourists and some populations are very close to roads and nature trails, they have been partially destroyed 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 14. Sonerila phuhinrongklaensis J. Wai & J.-M. Hu. A. Habit, B. Inflorescence, C. Bract, 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.All from P. Kamol 2020–1 (PSU). Drawn by K. Singkam.

FIGURE 15. Photos of Sonerila phuhinrongklaensis J. Wai & J.-M. Hu. A–B. Habit and habitat, C. Inflorescence and flowers, D. Immature fruits with persistent, spreading calyx, E. Seed, lateral view, F. Seed showing verrucose papillae and tubercles on antiraphal side. Photos by J. Sae Wai.