Sonerila subumbellata J. Wai

Wai, Jarearnsak Sae & Hu, Jer-Ming, 2023, Twelve new species of Sonerila (Sonerileae, Melastomataceae) from Thailand, Phytotaxa 620 (2), pp. 107-142 : 132-134

10. Sonerila subumbellata J. Wai & J.-M. Hu, sp. nov. ( Figures 20 , 21 ).

TYPE:— THAILAND. Yala Province, Betong District, Ban Piyamit 2, 5°52’36.15” N, 101° 1’10.35” E, 800–850 m, 28 April 2019 , J. Wai 2713 (holotype PSU!; isotypes BKF!, TAI!).

Diagnosis: Sonerila subumbellata is morphologically most similar to S. capitata Stapf & King (in King 1900: 35) by the anisophyllous leaves and subumbellate inflorescences, but differs in the shape of leaves (obliquely ovate or elliptic vs. obovate), broad leaf bases (vs. narrow), larger petals (6.5–13 × 3.5–6 mm vs. ca. 3 × 1.5 mm), larger hypanthia (3.5–5 mm long vs. 2–2.5 mm) and short-muricate capsules (vs. bristly muricate).

Perennial herbs; stems creeping to ascending, stout, terete, simple or branched, 4–10 mm thick, appressed-sericeous; main erect stems 10–30 cm high; internodes 2.5–8 cm long. Leaves opposite, anisomorphic, adaxially light to dark green or occasionally purplish, glossy, abaxially pale green or occasionally reddish purple, chartaceous when dry. Larger leaves obliquely ovate or elliptic, 7.5–17.5 × 4.5–10 cm, 1.5–2.2 times as long as wide, adaxially sparsely appressed-sericeous, abaxially densely appressed-sericeous along veins, apex acute to acuminate, base broad, obliquely cordate, margin ciliate; 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, 2–3 pairs; petioles 1–4 cm long, densely appressed-sericeous. Smaller leaves ovate, 0.5–2 × 0.5–1.5 cm, adaxially glabrous, abaxially appressed-sericeous along veins, apex acute or obtuse, base cordate, margin ciliate; venation basal acrodromous, usually with 3–5 main veins arising from the base; petioles sessile to subsessile, up to 2 mm long, appressed-sericeous. Inflorescences terminal or axillary, arranged in scorpioid cymes or subumbellate (derived from short-branched scorpioid cymes), 3–25- flowered, with scattered minute transparent glandular trichomes (seen under magnification) on peduncles, pedicels and hypanthia; peduncles erect or slightly curved, 1.5–6.5 cm long, green or reddish purple, sparsely appressed-sericeous; outer bracts sterile, leaf-like, persistent, oblong-lanceolate, lanceolate or oblanceolate, 6–8 × 2–2.5 mm long, margin ciliate, abaxially appressed-sericeous; inner (floral) bracts leaf-like, persistent, linear-oblong, narrowly lanceolate or subulate, 4–5 × 0.5–1 mm long, margin ciliate, abaxially sparsely appressed-sericeous or subglabrous. Flowers 3- merous; pedicels 2–4 mm long, greenish or reddish purple, glabrous. Hypanthium cup-shaped to campanulate, 3.5–5 × 3.5–4.5 mm, greenish or reddish, muricate; part of hypanthium free from ovary ca. 2 mm long. Calyx lobes 3, triangular, 2–2.5 × 2–3 mm, muricate. Petals short-clawed, elliptic or elliptic-rhomboid, 6.5–13 × 3.5–6 mm, apex acuminate, white or pinkish, glabrous on both surfaces. Stamens 3, equal, glabrous; filaments 2.5–5 mm long, white; anthers straight, oblong, deeply cordate at base, 2.5–4.5 mm long, yellow, apex opening with two pores. Ovary 1.5–2 mm long, 3-locular; ovary crown 0.7–1 mm high; ovules numerous; style 10–15 mm long, white or pinkish; stigma truncate, papillate. Capsule cup-shaped or turbinate, 4–5 × 4–5 mm, short-muricate. Seeds numerous, triangular ovoid, with an enlarged lateral raphe, 0.45–0.6 mm long, ca. 0.3 mm wide, 0.2–0.25 mm thick (measured through SEM), dark brown; testa cells with prominent tubercles on antiraphal side; tubercles cone-shaped or dome-shaped, usually with few minute verrucose papillae on the top.

Paratypes:— THAILAND. PENINSULAR: Songkhla Province, Ton Nga Chang Wildlife Sanctuary, 6°56’ N, 100°13’ E, 250 m, 17 August 1995, K. Karsen et al. 45731 ( AAU!, BKF!). Yala, Province, Bannang Sata District, Khao Pok Yo , 6°20’ N, 101°17’ E, 1000 m, 10 October 1991, K. Karsen et al. 42282 ( AAU!, BKF!, P!, PSU!); ibid., 950–1050, 16 June 1992, K. Karsen et al. 42918 ( AAU!, P!); ibid., 6 April 1995, Herb Trip 1059 ( BCU!); Betong District, Ban Piyamit, 24 May 1993, Herb Trip 422 ( BCU!); Ban Piyamit 2, 5°52’43.14” N, 101°1’18.92” E, 800–850 m, 3 June 2005, J. Wai 235 ( BKF!, PSU!, TAI!); ibid., 850 m, 11 April 2010, J. Wai 1869 ( PSU!); ibid., 5°52’41.4” N, 101° 1’18.3” E, 800–1000 m, 20 August 2014, J. Wai 2375 ( BKF!, PSU!, TAI!); ibid., 5°54’26.04” N, 101° 2’8.77” E, 850–1000 m, 23 July 2015, J. Wai 2453 ( PSU!); ibid., 5°54’23” N, 101° 2’11.3” E, 900 m, 19 August 2015, J. Wai 2468 ( PSU!, TAI!). Narathiwat Province, Sukhirin District , 5°46’36.08” N, 101°42’53.18” E, 163 m, 2 January 2016, J. Wai 2506 ( PSU!); Toh Moh, Khao Re Chaw , 550 m (1800 feet), 24 April 1931, M. C. Lakshnakara 727 ( BM!, BK!); Waeng District, Bala forest , 18 February 1999, P. Puudjaa & S. Cholkulchana 541 ( BKF!); ibid., 5°48’30” N, 101°48’36” E, 380 m, 9 March 2004, S. Chongko 256 ( CMUB!); ibid., 50–100 m, 1 January 2016, J. Wai 2503 ( PSU!); ibid., 350 m, 26 August 2017, J. Wai 2624 ( BK!, BKF!, PSU!, TAI!) . MALAYSIA. PENINSULAR MALAYSIA: Kedah, Gunung Lang, near Baling, 25 March 1938, Kiah SFN 35052 ( K, L, SING). Perlis, Mata Ayer Forest Reserve , 30–31 August 1992, G. W. H. Davison s.n. ( KEP).

Distribution:— Peninsular Thailand (Songkhla, Yala and Narathiwat Provinces), Peninsular Malaysia (Kedah and Perlis).

Habitat:— Terrestrial plant. This species was found growing in deep shade, often found along the streams in lowland humid and submontane evergreen forests, at elevations of 50–1050 m.

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

DNA barcodes:— OP431260 (ITS), OP480544 (accD-psal), OP452981 (ndhF), OP480669 (rpl16), OP503776 (trnS-trnG), OP558266 (ndhC-trnV), OP495580 (ndhF-rpl32). All sequenced from J. Wai 2375

Etymology:— The specific epithet “subumbellata” refers to the almost umbrella-like appearance of the inflorescences.

Vernacular name:—สาวสนมดง (Sao Sanom Dong) ( Thailand).

Proposed IUCN conservation status:— Vulnerable (VU) under criteria B1ab (iii)+B2ab (iii). This species is narrowly distributed in Southern Thailand and Northern Peninsular Malaysia. The known extent of occurrence (EOO) is less than 20,000 km 2 and the known area of occupancy (AOO) is less than 2,000 km 2. Some populations are very close to the road, and they are threatened by agricultural expansion. It has been noticed that the populations have declined over time. Therefore, we qualify this species as VU according to IUCN Red List guidelines Version 15.1 ( IUCN Standards and Petitions Committee 2022).

Figures

FIGURE 20. Sonerila subumbellata J. Wai & J.-M. Hu.A. Habit, B. Smaller leaf showing both adaxial (left) and abaxial (right) surfaces, C. Inflorescence, D. Bracts showing variation, E. Flower, F. Petals showing both adaxial (left) and abaxial (right) surfaces, G. Stamen, H. Longitudinal section of a flower showing hypanthium, stigma, style and ovary, I. Fruit showing top view (above) and side view (below). All from J. Wai 2713 (PSU). Drawn by P. Tippayasri.

FIGURE 21. Photos of Sonerila subumbellata J. Wai & J.-M. Hu. A. Habit and habitat, B. Inflorescences, C. Inflorescence in lateral view showing bracts, flowers and young fruits, D. Mature fruits, E. Seed, lateral view, F. Seed showing verrucose papillae and tubercles on antiraphal side. Photos by J. Sae Wai.