Sonerila epiphytica J. Wai

Wai, Jarearnsak Sae & Hu, Jer-Ming, 2023, Twelve new species of Sonerila (Sonerileae, Melastomataceae) from Thailand, Phytotaxa 620 (2), pp. 107-142 : 117-119

4. Sonerila epiphytica J. Wai & J.-M. Hu, sp. nov. ( Figures 8 , 9 ).

TYPE:— THAILAND. NORTHERN: Tak Province, Doi Thule , 17°36’4.39” N, 97°59’36.17” E, 1032 m, 15 August 2021 , J. Wai 2764 (holotype PSU!, isotypes BKF!, TAI!).

Diagnosis: Sonerila epiphytica is morphologically most similar to S. griffithii Clarke (1879: 539) in having thickened rhizomes and isophyllous leaves, but differs by its epiphytic habit, the presence of trichomes on the abaxial surface of leaf blade (vs. glabrous), shorter petals (8–9.5 mm long vs. 10–13.5 mm), glandular-pilose hypanthia (vs. glabrous), shorter stamens (filaments 3–4 mm long vs. 5.5–6 mm; anthers 2.5–3 mm long vs. 3.5–4 mm), shorter style (7–8.5 mm long vs. 12–13 mm) and sparsely pilose capsules (vs. glabrous).

Perennial herbs with tuberous rhizome, 5–15 cm high; rhizome thickened, fleshy, more or less globose, tubercled, 5–15 mm in diam.; stems erect or decumbent to ascending, usually unbranched, slender, quadrangular, 1.5–2 mm thick, fleshy, almost all parts covered with minute brown glandular trichomes (seen under magnification), mixed with long stipitate glandular trichomes (trichomes 1–1.5 mm long) and non-glandular trichomes; internodes 0.5–2 cm long. Leaves opposite decussate, isomorphic, adaxially light to dark green, with scattered numerous white spots along two sides of the midvein, abaxially pale green, often with reddish purple spots; membranaceous when dry; petioles 0.5–2.5 cm long, sparsely pilose; blades ovate, 1–4 × 1–2.7 cm, 1–1.3 times as long as wide, adaxially papillose-pilose, abaxially pilose, apex bluntly acute, obtuse or rounded, base cordate or rounded, 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, 2–4 pairs. Inflorescences terminal or axillary, scorpioid cymes, 1–9-flowered, with scattered minute transparent brown glandular trichomes, mixed with scattered long stipitate glandular trichomes on peduncles, pedicels and hypanthia; peduncles erect or slightly curved, 1–10 cm long, green or reddish purple, glandular-pilose; bracts minute, linear-triangular or subulate, 0.5–1.5 mm long, sometimes with minute trichomes. Flowers 3-merous; pedicels 4.5–7 mm long, green or reddish purple, glandular-pilose. Hypanthium cylindrical-obconical, 6–7 × 1.5–2 mm, purplish, glandular-pilose; part of hypanthium free from ovary 2–3 mm long. Calyx lobes 3, triangular-ovate, 1–1.5 × 1.5–2 mm. Petals short-clawed, elliptic or obovate, 8–9.5 × 4.5–5.5 mm, apex bluntly acute to acuminate, pink, adaxially glabrous, abaxially glandular-pilose along the midvein. Stamens 3, equal, glabrous; filaments 3–4 mm long, pinkish; anthers slightly incurved, deeply cordate at base, narrowing towards apex, 2.5–3 mm long, yellow, apex opening with two pores. Ovary 4–4.5 mm long, 3-locular; ovary crown 0.5–1 mm high; ovules numerous; style 7–8.5 mm long, pinkish; stigma capitate, papillate. Capsule cylindrical-obconical, slightly trigonous, 5–7 × 1.5–2 mm, sparsely pilose. Seeds numerous, narrowly triangular ovoid, 0.4–0.45 mm long, ca. 0.2 mm wide, ca. 0.2 mm thick (measured through SEM), dark brown; testa cells densely verrucose-papillose, with minute tubercles on antiraphal side.

Paratypes:— THAILAND. NORTHERN: Tak Province, Doi Thule , 17°36’4.39” N, 97°59’36.17” E, 1032 m, 5 November 2016, J. Wai 2575 et al. ( PSU!, TAI!) .

Distribution:— Thailand (Tak Province). It might be also found across the border in Myanmar.

Habitat:— Epiphytic on mossy tree trunks in lower montane forest, at elevations of 1000–1050 m.

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

DNA barcodes:— OP431193 (ITS), OP453023 (ETS), OP480492 (accD-psal), OP452954 (ndhF), OP480636 (rpl16), OP503746 (trnS-trnG), OP558233 (ndhC-trnV), OP495548 (ndhF-rpl32). All sequenced from J. Wai et al. 2575.

Etymology:— The specific epithet “epiphytica” refers to the epiphytic habit of this species.

Vernacular name:—สาวสนมดอยทูเล (Sao Sanom Doi Thule) ( Thailand).

Proposed IUCN conservation status:— Data Deficient (DD). This species is known only from the type locality near Thai-Myanmar border. Data on population size and the threats for this species is insufficient, further field surveys are needed. We suggest this status as DD according to IUCN Red List guidelines Version 15.1 ( IUCN Standards and Petitions Committee 2022).

Figures

FIGURE 8. Sonerila epiphytica 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. All from J. Wai 2764 (PSU). Drawn by K. Singkam.

FIGURE 9. Photos of Sonerila epiphytica J. Wai & J.-M. Hu. A. Habit and habitat, B. Habit showing tuberous rhizome. 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.