Pinanga nuichuensis A.J.Hend., N.K.Ban & B.V.Thanh

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

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).