Pinanga spiralis Henderson & Nguyen Quoc Dung, 2017

Henderson, Andrew & Dung, Nguyen Quoc, 2017, New species of Lanonia, Licuala, and Pinanga (Arecaceae) from Vietnam, Phytotaxa 323 (2), pp. 159-172 : 170-171

Pinanga spiralis Henderson & Nguyen Quoc Dung sp. nov. ( Fig. 11 ).

Type:— VIETNAM. Khanh Hoa: Khanh Vinh District, road from Nha Trang to Da Lat, 12.233N, 108.766E, 605 m, 7 July 2010, A. Henderson & Bui Van Thanh 3678 (holotype HN!, isotype NY!).

It differs from other species of Pinanga in Vietnam with spirally arranged triads ( P. cattienensis , P. nuichuaensis ) in its leaf sheaths forming a crownshaft and multifold pinnae.

Stems clustered, 0.5–6.0 m tall, 1.5–3.0 cm diameter, green, covered with scattered reddish-brown scales. Leaves 7; sheaths closed and forming crownshafts, 30.0 cm long, green or yellowish-green, with brown scales; ocreas 1.5 cm long, appearing as two ‘ears’ either side of sheath, early deciduous; petioles 60.0–130.0 cm long, green; rachises 60.0–200.0 cm long; pinnae 8–30 per side of rachis, lanceolate, slightly contracted at the bases, regularly arranged, distantly spaced, multifold, with prominent, raised veins adaxially; middle pinna 48.5–53.0 cm long, 2.7–3.5 cm wide, apical pinna 30.0 cm long, 2.4–3.4 cm wide at the middle, praemorse. Inflorescences infrafoliar, pendulous; peduncles 1.5–2.0 cm long, 1.0 cm wide; prophylls not seen; rachises 0.5 cm long; rachillae 3–6, 11.5–15.0 cm long, glabrous; triads spirally arranged; staminate flowers not seen; pistillate flowers to 3 mm long; sepals to 2.0– 2.5 mm long, imbricate, rounded at the apices, minutely ciliate; petals to 3.0 mm long, imbricate, minutely ciliate; fruits 1.5 cm long, 0.6 cm diameter, ellipsoid, reddish at maturity; endosperm ruminate.

Distribution and habitat:—Southern Vietnam in Dak Lak, Khanh Hoa, and Lam Dong provinces in lowland rainforest at 203–550 m elevation.

Taxonomic notes:— Two other species of Pinanga in Vietnam ( P. cattienensis , P. nuichuaensis ) have spirally arranged triads. Pinanga cattienensis differs from P. spiralis in having poorly developed crownshafts with the inflorescences pushing through the disintegrating leaf sheaths. Pinanga nuichuaensis differs in its single-fold pinnae. The single specimen examined from Hon Heo, a mountain near Nha Trang, is somewhat tentatively included here; it is considerably smaller than the others.

Additional specimens examined. VIETNAM. Khanh Hoa: Ninh Hoa District, Tien Du commune, Hon Heo mountain , 12.450N, 109.233E, 334 m, 6 July 2010, Henderson & Bui Van Thanh 3669 ( HN, NY) ; Dien Khanh District, Hon Ba Nature Reserve , 12.116N, 109.000E, 203 m, 9 July 2010, Henderson & Bui Van Thanh 3692 ( HN, NY) ; Khanh Vinh district, Khanh Trung commune, Suoi Ca village , road from Khanh Vinh to hydroelectric site, 12.336N, 108.855E, ca. 500 m, 20 April 2013, Henderson & Nguyen Quoc Dung 3865 ( NY, VFM) ; Hon Ba Nature Reserve , road to summit, 12.11N, 108.98E, ca. 500 m, 6 July 2014, Henderson & Nguyen Quoc Dung 3915 ( NY, VFM) ; same locality, 12.108N, 108.989E, ca. 600 m, 7 July 2014, Henderson & Nguyen Quoc Dung 3920 ( NY, VFM) ; new road from Nha Trang to Da Lat , 12.232N, 108.775E, ca. 550 m, 9 July 2014, Henderson & Nguyen Quoc Dung 3937 ( NY, VFM) .

Figures

FIGURE 11. Pinanga spiralis. Left, habit (from Henderson & Bui Van Thanh 3692). Right, inflorescence (from Henderson & Bui Van Thanh 3669).