Licuala dakrongensis A.J.Hend., N.K.Ban & B.V.Thanh

Henderson, Andrew, Ban, Ninh Khac & Thanh, Bui Van, 2010, New species of Areca, Pinanga, and Licuala (Arecaceae) from Vietnam, Phytotaxa 8, pp. 34-40 : 36-38

Licuala dakrongensis A.J.Hend., N.K.Ban & B.V.Thanh , sp. nov. ( Plate 2 )

A Licuala bachmaensis habitatio dissimilis rachilla et floribus glabris differt.

Type:— VIETNAM. Quang Tri Province: Da Krong District, Da Krong Nature Reserve , near Ba Long Commune, 16.651 N, 107.037 E, ca. 500 m, 28 February 2009, A . Henderson , B. V . Thanh , N. V. Thang & T. M . Vu 3498 (holotype: HN!, isotypes: AAU! K! NY!) .

Stems solitary or clustered, 1–4 m tall, 5–8 cm in diameter, sometimes short and subterranean, often covered with persistent leaf bases. Leaves 16–21; leaf sheaths 12 cm long, with prominent, 20 cm long ocreas; petioles 1.3–2.5 m long, 0.5–0.6 cm wide near the apex, with small, black spines on basal one third to one half; blades 92–140 cm wide, split into 18–27 segments, these with straight sides, the central few remaining joined to one another distally; middle segments only slightly wider than the others, not split, strongly petiolulate, 51–74 cm long, 9–21 cm wide at the apex; indentations leading to adaxial folds 4–5.5 cm deep, those leading to abaxial folds 0.4–0.5 cm deep, indentations deeper on lateral segments. Plants monoecious. Inflorescences elongate, 1.65–2 m long, erect amongst the leaves but not exceeding them; prophylls 12–25 cm long; peduncles 40–77 cm long; rachis 50 cm or more long with 6–10 partial inflorescences, these branched to 2 orders, each subtended by a tubular bract, scarcely tattering at the apex, the proximal-most few partial inflorescences with 2, to 2 cm long bracteoles at point of insertion on rachis; rachillae 2–11 on each partial inflorescence, 11–20 cm long, 2 mm diameter, glabrous, with prominent floral stalks; flowers solitary or in groups; flower buds globose, 2–2.7 mm long; calyx tubular, 2 mm long, glabrous, briefly 3-lobed at the apex; corolla white, glabrous, not recurving at anthesis; flowers with 6 stamens, staminal ring very short, the filaments 0.3 mm long; anthers 0.3 mm long, style well developed. Fruits ellipsoid, 1.1 cm long, 0.5 cm diameter, with perianth appressed to base of the fruit.

Distribution and habitat:— Endemic to central Vietnam in Quang Tri, Quang Nam, Thua Thien-Hue, and Kon Tum Provinces, on slopes of mountains in broad-leafed, evergreen, primary closed forest on sandstone, shale, or granite rocks.

Local names and uses:— ao toi, ke, la non. The leaves are used to make rain coats.

Additional specimens examined (paratypes): — VIETNAM. Quang Tri: Da Krong District, Da Krong Nature Reserve, Me Tre , Thuong Nguyen Commune , 16.662 N, 106.935 E, ca. 400 m, 1 March 2009, Henderson et al. 3501 ( AAU, HN, K, NY); 3502 ( AAU, HN, K, NY) . Quang Nam: Nam Giang District, Ta Bhing commune, Song Thanh Nature Reserve , road 14 D to Laos , 15.660 N, 107.665 E, 200 m, 11 March 2009, Henderson et al. 3559 ( AAU, HN, K, NY); Giang District , Ha Ra , 13 July 1986, LX-VN 2959 ( HN) . Thua Thien-Hue: A Luoi District, Sao La Nature Reserve, 16.077 N, 107.488 E, 892 m, 7 March 2009, Henderson et al. 3538 ( HN, K, NY); Phu Loc District , Bach Ma National Park , N slope of Bach Ma mountain , 16°12’N, 107°50’E, 400 m, 1 May 2003, N. T . Hiep et al. HLF 1497 ( HN) . Kon Tum: Dak Glei District, about 7 km S of Dak Gley town near Dak Pet village, 12 November 1995, Averyanov et al. VH 1518 ( HN, K, MO) .

Discussion: — Licuala dakrongensis is monoecious and appears most similar to L. bachmaensis Henderson et al. (2008a: 145) . Both species have the central few leaf segments remaining joined to one another distally, but they differ in their rachillae and flowers. The rachillae of Licuala bachmaensis are densely covered with hairs, the calyx and corolla are densely hairy, and the pistil is sparsely hairy. Rachillae and flowers of L. dakrongensis are glabrous. The two species are also found in different habitats: Licuala bachmaensis has been found only in open, highly disturbed habitats such as Acacia and Eucalyptus plantations and waste places near roads, whereas L. dakrongensis has been seen only in primary forest on steep slopes.

Figures

PLATE 2. Licuala dakrongensis. Left – habit. Right - partial inflorescence.