Pinanga nuichuensis 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 : 38-39

Pinanga nuichuensis A.J.Hend., N.K.Ban & B.V.Thanh , sp. nov. ( Plate 3 )

A speciebus generis Pinangae cognitis Vietnam pinnis 19–40, linearis, regulariter dispositis et triadibus spiraliter dispositis differt.

Type:— VIETNAM. Ninh Thuan: Ninh Hai District, Nui Chua National Park , 11°48’N, 109°09’E, ca. 800 m, 26 October 2009, A . Henderson , B. V . Thanh , N. Q . Dat & A R . Cui 3645 (holotype: HN!, isotypes: K! NY!) .

Stems solitary or clustered, 2.5–5 m tall, 1–4 cm in diameter, densely covered with reddish-brown scales. Sheaths closed, forming crownshafts, to 30 cm long, yellowish, densely covered with reddish-brown scales; ocreas short, early deciduous; petioles to 10 cm long; rachises 49–109 cm long; pinnae 19–40 per side of rachis, linear, acuminate, regularly arranged and spreading in the same plane; middle pinnae 30–51 cm long, 2 cm wide at the middle, apical pinnae 20 cm long, 2 cm wide at the middle, praemorse; veins prominent adaxially. Inflorescences infrafoliar, pendulous; peduncles 1 cm long, 0.5 cm wide; prophylls not seen; rachises 2 cm long; rachillae 5, 12– 13 cm long, rounded in cross-section, glabrous; triads spirally arranged, subtended by prominent, apiculate, 1 mm high bracteoles; flowers subtended by prominent bracteoles; staminate flowers not seen; pistillate flowers 4 mm long; sepals 3 mm long, imbricate, the margins not ciliate, not acuminate; petals 3 mm long, imbricate, the margins not ciliate, not acuminate; ovary 3.5 mm long; fruits immature; endosperm ruminate.

Distribution and habitat: — Vietnam in Ninh Thuan Province, near the summit of Nui Chua mountain on rocky slopes in lowland rainforest at 800 m elevation.

Local names and uses:— cau lui, cau lua. No uses recorded.

Additional specimen examined (paratype): — VIETNAM. Ninh Thuan: Ninh Hai District, Nui Chua National Park , 11°48’N, 109°10’E, ca. 800 m, 27 July 2007, Henderson et al. 3474 ( HN, NY) .

Discussion:— The material on which this new species is based did not key out using the regional monograph of Henderson (2009). It differs from Pinanga baviensis Beccari (1910: 193) , P. cattienensis Henderson et al. (2008b: 64) , P. cupularis Henderson et al. (2008b: 64) , P. humilis Henderson et al. (2008b: 68) , P. kontumensis Henderson et al. (2008b: 68) and P. quadrijuga Gagnepain (1937: 156) in its pinnate leaves with 19–40 linear pinnae (versus 3–12 broad, curved pinnae or leaves undivided). It is more similar in leaf morphology to P. annamensis Magalon (1930: 152) and P. declinata Henderson et al. (2008b: 65) , although its pinnae are more numerous (19–40 versus 8–21) and narrower (2 cm versus 3.5–5 cm wide at the middle). It also differs from these two species in its spirally arranged triads (versus arranged in two opposite rows along the rachillae).

Figures

PLATE 3. Pinanga nuichuensis. Left – leaf. Right – inflorescence.