Syzygium scabrum Tagane, Soulad. & Yahara, 2018

Tagane, Shuichiro, Dang, Van-Son, Souladeth, Phetlasy, Nagamasu, Hidetoshi, Toyama, Hironori, Naiki, Akiyo, Fuse, Kengo, Tran, Hop, Yang, Ceng-Jui, Prajaksood, Amornrat & Yahara, Tetsukazu, 2018, Five new species of Syzygium (Myrtaceae) from Indochina and Thailand, Phytotaxa 375 (4), pp. 247-260 : 253-255

Syzygium scabrum Tagane, Soulad. & Yahara , sp. nov. ( Figure 5 ).

TYPE: — THAILAND. Buengkan Province, Bung Khla, Phu Wua Wildlife Sanctuary, 22 Nov. 2015, Phonsena P., de Wilde W.J.J.O & Duyfjes B.E.E 7280 [fl. & fr.] (holotype BKF!, isotypes BK, KKU).

Syzygium scabrum is similar to S. vestitum Merrill & Perry (1938: 110) in having reddish brown hairs on twigs, leaves and hypanthium, but differs in having more or less cordate leaf base (vs. broadly cuneate to rounded in S. vestitum ), scabrid on both sides of leaf surfaces (vs. glabrous except on veins on abaxial side, never scabrid on adaxial side), more secondary veins (16–30 pairs vs. 10–16 pair) and longer styles (8–15.5 mm long vs. 6 mm long).

Tree, 10 m tall. Twigs terete, 3–3.5 mm in diam., densely covered with yellowish brown, dark grayish brown, reddish brown hairs, internode 1.9–6.5 cm long. Leaves opposite, blade ovate-elliptic, ovate-oblong, (6.3–)11.5–19.5 × (2.2–) 3.1–5.6 cm, 2.7–3.8 times longer than wide, chartaceous, apex acuminate, acumen to 1.2 cm long, base slightly cordate or rounded, margin entire, recurved, dark dull green to dark yellow-green abaxially, dull brownish yellow to brown abaxially, coarsely reddish brown hairy and scabrid on both surfaces, especially denser on midrib and secondary veins, midrib sunken adaxially, prominent abaxially, secondary veins (16–)21–26(–30) pairs, (2–) 4–7 mm apart, sunken adaxially, prominent abaxially, intersecondary veins more or less distinct, prominent abaxially, intramarginal veins 1 or 2, (0.6–) 1–4 mm from margin, prominent abaxially, outer ones (0.1–) 0.6–1 mm from margin, prominent to indistinct; petiole (2–) 3–4.5 mm long, densely scabrid as in twig. Inflorescences terminal, paniculate, 6–15 cm long, peduncle 2–8 cm long, densely scabrid with reddish brown hairs. Flower buds ca. 3.5 mm in diam. Hypanthium funnel-shaped, 4–5 mm long, densely covered with brown hairs, pseudostipe 2–3 mm long, bracteoles linear, ca. 4 mm long, densely brown hairy on both surfaces. Sepals 4, semi-circular, ca. 1.1 mm long, petals 4, orbicular, 2.8–3.5 mm in diam., membranous, with 30–50 gland dots per petal. Stamens many, to 12 mm long, anthers 0.2–0.4 mm long, filaments 0.8–11.6 mm long, white (in vivo), glabrous. Style (8–) 13–15.5 mm long, glabrous. Ovary 2-locular, 5–10 per locule. Fruits (sub)globose, ca. 2.2 cm in diam., hairy when young, later glabrous except near calyx ring, calyx ring ca. 4 mm in diam., rim ca. 0.5 mm high. Seed 1, subglobose, 1.7 cm high, 1.5 cm in diam., dark brown, glabrous.

Paratypes:— LAOS. Vientiane Province: Thoulakhom District, Phou Khao Khouay National Protected Area, Ban Tha Heua , 18°21′15.82″N, 102°48′07.35″E, 769 m elev., 22 May 2011, Souladeth P. 91 [fl.] (FOF, KKU!) ; ibid., 26 Dec. 2017, Yahara T., Tagane S., Souladeth P., Nagamasu H., Naiki A., Chayer S. & Kongxaisavath D. L1438 [fr.] (BKF, FOF!, KYO!, NHL) ; ibid., 18°23′19.08″N, 102°54′40.61″E, elev. 695 m, Yahara T., Tagane S., Souladeth P., Nagamasu H., Naiki A., Chayer S. & Kongxaisavath D. L 1727 (FOF, KYO!) ; ibid., 23 Apr. 2011, Souladeth P. 86 [fr.] (FOF!, KKU) ; Phou Khao Khouay , 29 Oct. 1971, Vidal 5969 [fr.] (P [P00589453], image!) . THAILAND. Nakhon Phanom Province, Ban Phaeng, Phu Langka National Park, Tat Kham Fall , 17°57′00″N, 104°09′44″E, elev. 150 m, 25 Aug. 2001, Pooma R., de Wilde W.J.J.O., Duyfjes B.E.E., Chamchumroon V. & Phattarahirankanok K. 2613 [fl.] (BKF!) .

Distribution:— Laos (Vientiane Province: Phou Khao Khouay National Protected Area), Thailand (Nakhon Phanom Province: Phu Langka National Park, Buengkan Province: Phu Wua Wildlife Sanctuary).

Habitat and Ecology:— In hill evergreen forest, at altitudes of 690–770 m in Laos, and in dry evergreen forest at an altitude of 150 m in Thailand.

Phenology:— Flowering specimens collected in August and November, fruiting in October to December.

DNA barcodes:— LC381850 (rbcL), LC381853 (matK); sequenced from Yahara et al. L1438.

Etymology:— The species epithet refer to its nature of roughened (scabrid) surfaces of twigs and leaves caused by dense hairs.

Vernacular name:—หวาขน (Wa Khon) ( Thailand); ຫວາຂນ (Wa Khon) (Laos).

Preliminary conservation assessment:— Endangered (EN). Based on collections and our field observations, S. scabrum is considered to be widely distributed in forests at lower to high elevations (150–800 m) in Northeast Thailand and Central Laos, and the area of occupancy (AOO) of this species calculated based on the collection localities is less than 2200 km 2 with some disturbed localities in Laos. Therefore we qualify this species as EN according to the IUCN criteria of B1a & b ( IUCN 2012).

Note 1: —This species has been confused with S. vestitum (type: Mt. Bana, Vietnam, J. & M.S. Clemens 3296, K, image!) by Souladeth & Meesawat (2012), Chantaranothai (2014), and Soh & Parnell (2015), but it is clearly distinguished from S. vestitum by the above diagnostic characters. Syzygium vestitum is restricted to northern to central Vietnam and southern China (southeast Yunnan) ( Hô 2003, Chen & Craven 2007, from our field observations in SE Asia). The sequence of matK region of S. scabrum (GenBank accession no. LC381853) differs 7 bp of the total 760 bp from the S. vestitum (LC381852: Tagane et al. V2522 (FU!) from Bach Ma National Park, Central Vietnam, ca. 25 km apart from the type locality of S. vestitum ), supporting the separation of the two species.

Note 2: —The specimens Souladeth P. 86, Souladeth P. 91 and Yahara T. et al. L1438 were collected from the same tree.

Figures

FIGURE 5. Syzygium scabrum Tagane, Soulad. & Yahara. A) Leafy twig, B) Portion of lower leaf surface, C) Inflorescence, D) Flowers and flower buds, E) Young fruit, F) Fruit and seed. Photographs:A & B for Yahara et al. L1727, taken by S. Tagane on Dec. 2017; C & D for Souladeth 86, taken by P. Sutthisaksopon on 24 May 2011; E & F for Phonsena et al. 7280 taken by P. Phonsena on 22 Nov. 2015.