Sonerila reptans J. Wai

Wai, Jarearnsak Sae & Hu, Jer-Ming, 2023, Twelve new species of Sonerila (Sonerileae, Melastomataceae) from Thailand, Phytotaxa 620 (2), pp. 107-142 : 130-131

9. Sonerila reptans J. Wai & J.-M. Hu, sp. nov. ( Figures 18 , 19 ).

TYPE:— THAILAND. NORTHERN: Nan Province, Bo Kluea District, Ban Sapan, Sapan Waterfall , 19°11’17.80” N, 101°11’41.30” E, 750–900 m, 8 October 2017, J. Wai 2641 (holotype PSU!, isotype TAI!).

Diagnosis: Sonerila reptans is morphologically most similar to S. cantonensis Stapf (1892: 302) in having woolly young stems, isophyllous leaves, and long woolly petioles, but differs by its creeping then ascending habit (vs. usually erect), pubescent leaves (vs. sparsely strigose) and usually suprabasal acrodromous venation (vs. pinnate), shorter anthers (6–7 mm long vs. ca. 8 mm), woolly capsules (vs. glabrous).

Perennial herbs; stems creeping then ascending, branched, slender, terete or subterete, 2–3 mm thick, almost all parts covered with minute brown glandular trichomes (seen under magnification), young parts densely white woolly, trichomes turn to rusty brown in old parts; erect parts from ground 5–10 cm high; internodes 0.5–5 cm long. Leaves opposite decussate, isomorphic, light to dark green or sometimes reddish purple, chartaceous or submembranaceous when dry; petioles 0.5–1.7 cm long, long white woolly; blades elliptic or elliptic-ovate, 1–5 × 0.7–2.5 cm, 1.1–2 times as long as wide, pubescent on both surfaces, apex acute or obtuse, base rounded, obtuse or cordate, margin shallowly serrulate; venation usually suprabasal acrodromous or occasionally subpinnate, with 2–3 pairs of secondary veins. Inflorescences usually terminal, scorpioid cymes, 3–5-flowered, with scattered minute transparent brown glandular trichomes (seen under magnification) mixed with long white woolly trichomes on peduncles, bracts, pedicels and hypanthia; peduncles erect or slightly curved, 2–3 cm long, green or purplish, densely woolly; bracts minute, subulate or linear-lanceolate, ca. 1.5 mm long. Flowers 3-merous; pedicels 1.5–3 mm long, green or purplish, densely woolly. Hypanthium cylindrical-campanulate or obconical, 5–6.5 × ca. 2.5 mm, greenish, densely woolly; part of hypanthium free from ovary 3–3.5 mm long. Calyx lobes 3, triangular, ca. 2 × 1.5 mm. Petals short-clawed, elliptic or elliptic-ovate, 9–12 × 4.5–5 mm, apex acuminate, pinkish, adaxially glabrous, abaxially glandular pilose along the midvein. Stamens 3, equal, glabrous; filaments 7–8.5 mm long, white; anthers slightly incurved, deeply cordate at base, narrowing towards apex, 6–7 mm long, yellow, apex opening with two pores. Ovary 3–3.5 mm long, 3-locular; ovary crown ca. 1.5 mm high; ovules numerous; style 17–19 mm long, white; stigma capitate, papillate. Capsule obconical, slightly trigonous, 5.5–6 × 3–4.5 mm, woolly. 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 to nearly black; testa cells densely verrucose-papillose, with minute tubercles on antiraphal side; tubercles dome-shaped, smooth or with few minute verrucose papillae on the top.

Paratypes:— THAILAND. NORTHERN: Nan Province, Bo Kluea District, Ban Sapan, Sapan Waterfall , 19°12’ N, 101°13’ E, 600 m, 17 November 1993, K. Larsen et al. 44499 ( K!); ibid., 750–900 m, 1 August 2017, J. Wai 2614 ( PSU!).

Distribution:— Thailand (Nan Province). It might be expected also to occur across the border in Laos.

Habitat:— Terrestrial plant. This species was found growing in shaded areas, on the cliffs, hill slopes, or along the streams in evergreen forests, at elevations of 600– 900 m.

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

DNA barcodes:— OP431245 (ITS), OP453053 (ETS), OP480534 (accD-psal), OP452975 (ndhF), OP480662 (rpl16), OP503770 (trnS-trnG), OP558260 (ndhC-trnV), OP495572 (ndhF-rpl32). All sequenced from J. Wai 2641.

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

Vernacular name:—สาวสนมเลื้อย (Sao Sanom Lueai) ( Thailand).

Proposed IUCN conservation status:— Data Deficient (DD). This species is known only from the type locality near the Thai-Laos border. Information on population size and the threats for this species is inadequate. More extensive 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 18. Sonerila reptans J. Wai & J.-M. Hu.A. Habit, B. Bract, C. Flower, D. Petals showing adaxial surface (left), abaxial surfaces (central) and side view (right), E. Stamen, F. Longitudinal section of a flower showing hypanthium, stigma, style and ovary. G. Immature fruits. H. Fruit.All from J. Wai 2641 (PSU). Drawn by P. Tippayasri.

FIGURE 19. Photos of Sonerila reptans J. Wai & J.-M. Hu. A. Habit and habitat, B. Habit showing flowering shoots with leaves, C. Inflorescences, D. Fruits, E. Seed, lateral view, F. Seed showing verrucose papillae and tubercles on antiraphal side. Photos by J. Sae Wai.