Sonerila peninsularis J. Wai

Wai, Jarearnsak Sae & Hu, Jer-Ming, 2023, Twelve new species of Sonerila (Sonerileae, Melastomataceae) from Thailand, Phytotaxa 620 (2), pp. 107-142 : 122-125

6. Sonerila peninsularis J. Wai & J.-M. Hu, sp. nov. ( Figures 12 , 13 )

TYPE:— THAILAND. PENINSULAR: Songkhla Province, Hat Yai District, Kho Hong Hill , 7° 0’55.17” N, 100°31’12.80” E, 360 m, 24 October 2020 , J. Wai 2758 (holotype PSU!, isotypes BKF!, TAI!).

Diagnosis: Sonerila peninsularis is morphologically most similar to S. calophylla Ridley (1912: 5) in having quadrangular stems and isophyllous leaves, but differs by its subterranean globose tuber (vs. irregularly shaped rhizome), long stipitate glandular trichomes on abaxial midvein of the petals (vs. absent), shorter filaments (2–4 mm long vs. 4.5–5.5 mm), smaller anthers (1.5–2.5 mm long vs. 4.5–6 mm) and shorter style (6–9 mm long vs. 10–14 mm).

Perennial herbs with subterranean tuber, 5–25 cm high; tuber more or less globose, 3–10 mm in diam.; stems erect or decumbent to ascending, usually unbranched, quadrangular, 2–5 mm thick, fleshy, almost all parts covered with minute brown glandular trichomes (seen under magnification); internodes up to 2 cm long. Leaves opposite decussate, isomorphic, light to dark green, brownish or reddish purple, often with scattered numerous white spots, membranaceous when dry; petioles 0.5–2 cm long; blades ovate, elliptic, or lanceolate, 2.5–10 × 1–4.5 cm, 1.5–2.6 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 cordate, rounded or broadly cuneate, 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 occasionally sub-opposite manner, 2–5 pairs. Inflorescences terminal or axillary, scorpioid cymes, 5–20-flowered, with scattered minute transparent brown glandular trichomes (seen under magnification) on peduncles, pedicels and hypanthia; peduncles 3–8 cm long, erect or slightly curved, greenish or purplish; bracts minute, narrowly triangular, 0.25–0.5 mm long. Flowers 3-merous; pedicels 1.5–4 mm long, purplish. Hypanthium cylindrical, narrowly campanulate or obconical, 5–6 × 2–2.5 mm, purplish or greenish, occasionally with few long stipitate glandular trichomes (trichomes ca. 0.5 mm long); part of hypanthium free from ovary 1.5–2.5 mm long. Calyx lobes 3, triangular-ovate, 0.5–1 × 1.5–2 mm. Petals short-clawed, elliptic or obovate, 6.5–11 × 3–4.5 mm, apex acuminate, pinkish, adaxial surface glabrous, abaxial surface with few long stipitate glandular trichomes along the midvein (trichomes ca. 0.5 mm long). Stamens 3, equal, glabrous; filaments 2–4 mm long, white; anthers slightly incurved, cordate at base, narrowing towards apex, 1.5–2.5 mm long, yellow, apex opening with two pores. Ovary 3–4 mm long, 3-locular; ovary crown ca. 1 mm high; ovules numerous; style 6–9 mm long, white; stigma capitate, papillate. Capsule obpyramidal, trigonous, 5–6 × 3–4 mm, glabrous. Seeds numerous, triangular ovoid, 0.4–0.5 mm long, ca. 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: Songkhla Province, Hat Yai District, Kho Hong Hill , 400 m, 23 September 1984, J. F. Maxwell 84–248 ( BKF!, PSU!); ibid., 15 December 1984, J. F. Maxwell 84–513 ( BKF!, PSU!); ibid., 15 December 1984, J. F. Maxwell 84–514 ( BKF!, PSU!); ibid., 7° 0’55.17” N, 100°31’12.80” E, 360 m, 19August 2016, J. Wai 2527 ( PSU!); ibid., 7° 0’54.03”N, 100°31’12.25”E, 350 m, 10 December 2016, J. Wai 2603 ( BKF!, PSU!, TAI!); Ton Nga Chang Waterfall , 80–350 m, 19 December 1979, T. Shimizu et al. T27713 ( BKF!, KYO!); ibid., 100 m, 10 January1984, P. Sirirugsa 736 ( PSU!); ibid., 250 m, 27 December 1984, J. F. Maxwell 84–571 ( PSU!); ibid., 6°56’ N, 100°13’ E, January 1992, P. Puudjaa 52 ( BKF!); ibid., 2 February 2022, J. Wai 2740 ( PSU!); Na Thawi District, Khao Nam Kang , 6°45’ N, 100°43’ E, 100–150 m, 20 October 1991, K. Larsen et al. 42421 ( AAU!, P!); ibid., 13 June 1992, K. Larsen et al. 42849 ( AAU!); ibid., 13 March 1998, Puangpen et al. N321 ( QBG!); ibid., 6°35’37.06” N, 100°35’22.27” E, 150 m, 21 August 2015, J. Wai 2475 ( PSU!, TAI!); ibid., 14 December 2015, J. Satthaphorn s.n. ( PSU!). Narathiwat Province, Bacho District , 9 June 1961, K. Bunchuai 200 ( BKF!); ibid., 10 December 1968, P. Sangkhachand 1550 ( BK!, KYO!); ibid., 13 December 1968, S. Phusomsaeng 4 ( BKF!, C!); ibid., 6°31’ N, 101°39’ E, 17 October 1970, Ch. Charoenphol et al. 3939 ( AAU!, L!) .

Distribution:— Thailand (Songkhla and Narathiwat Provinces).

Habitat:— Terrestrial plant. This species was often found growing in shaded areas of hill slopes and rocky habitats in lowland forests, at elevations of 50– 400 m.

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

DNA barcodes:— OP431230 (ITS), OP453046 (ETS), OP480523 (accD-psal), OP452970 (ndhF), OP480656 (rpl16), OP503765 (trnS-trnG), OP558254 (ndhC-trnV), OP495565 (ndhF-rpl32). All sequenced from J. Wai 2758.

Etymology:— The specific epithet “ peninsularis ” refers to the distribution of this species being restricted to Peninsular Thailand.

Vernacular name:—สาวสนมใต้ (Sao Sanom Dai) ( Thailand).

Proposed IUCN conservation status:— Endangered (EN) under criteria B1ab (iii)+B2ab (iii). This species is known only from four locations in Southern 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 this species is found in lowlands and some populations are very close to agricultural areas and can be affected by human disturbance. Therefore, we qualify this species as EN according to IUCN Red List guidelines Version 15.1 ( IUCN Standards and Petitions Committee 2022).

Figures

FIGURE 12. Sonerila peninsularis J. Wai & J.-M. Hu. A. Habit, B. Bract, C. Flower, D. Petals showing both adaxial (left) and abaxial (right) surfaces, E. Stamen, F. Longitudinal section of a flower showing hypanthium, stigma, style and ovary.All from J. Wai 2758 (PSU). Drawn by P. Tippayasri.

FIGURE 13. Photos of Sonerila peninsularis J. Wai & J.-M. Hu.A–B. Habit and habitat, C. Habit showing leaves, flowering shoots and tuberous rhizome, D. Inflorescences and flowers, E. Seed, lateral view, F. Seed showing verrucose papillae and tubercles on antiraphal side. Photos by J. Sae Wai.