Lanonia montana Henderson & Nguy

Henderson, Andrew & D ựng, Nguy ễn Qu ốc, 2022, A revision of Lanonia (Arecaceae, Coryphoideae, Livistoninae), Phytotaxa 532 (3), pp. 209-245 : 235-236

15. Lanonia montana Henderson & Nguy ễn Quốc Dựng sp. nov. Type:— VIETNAM. Khanh Hoa province, Khanh Vinh district, road from Nha Trang to Da Lat , 12.200N 108.733E, 1,488 m, 8 July 2010, A. Henderson & Bui Van Thanh 3689 (holotype HN!, isotype NY!). Fig. 15 .

Stems 1.6(1.0–2.5) m long, 2.0 cm diameter, solitary. Leaves 13; ligules 18.0 cm long, papery, not disintegrating into fibers; sheaths and proximalmost part of petioles with dense, flat, black scales; petioles 59.7(49.0–70.0) cm long, 0.5(0.3–0.7) cm wide at the apex; petiole thorns usually stout, reddish-brown or dark brown, some bifid or often some in pairs, on proximalmost part of petiole; hastulas flat, rounded, not infolded; leaf blades 40.0 cm wide; costas 6.3(2.0–18.0) cm long, triangular, with a pulvinus at the apex abaxially, with the numerous segments free almost to the base; segments 16(11–20) per leaf, mottled or not mottled, with minute, reddish-brown scales abaxially, with (on dried specimens) straight margins; middle segments 23.9(18.3–31.0) cm long, 6.2(3.8–12.0) cm wide at the apex; apices of middle segments with adaxial splits much deeper than abaxial ones. Inflorescences 50.0 cm long; prophylls 15.0 cm long; peduncles 33.0 cm long; rachis bracts narrowly tubular, splitting apically, not or sparsely tomentose; rachillae not filiform nor thick and ribbed, sparsely to moderately covered with short, mostly simple, brownish hairs; staminate rachises absent; staminate partial inflorescences 1, branched to 3 orders; staminate rachillae number not recorded, 14.8(14.5–15.0) cm long, 0.9(0.8–0.9) mm diameter; staminate flowers 1.7 mm long; sepals not pedicellate at the base, not densely hairy; petals rounded at the apex; stamens with alternately long and short filaments and small, almost square anthers; filaments not elongate; pistillodes undivided; pistillate rachises absent; pistillate partial inflorescences 1, branched to 2–3 orders; pistillate rachillae on proximalmost partial inflorescence 11, 11.6(11.5–11.7) cm long, 1.1(1.01.1) mm diameter; pistillate flowers 2.5 mm long, with short styles; fruits not recorded; seeds not recorded.

Distribution and habitat:— Southern Vietnam in Khanh Hoa province in montane rainforest at 1,201(800–1,488) m elevation ( Fig. 14 ).

Taxonomic notes:— Specimens formerly included in L. hexasepala (see notes under that species) differ from others by their non-filiform (versus filiform) rachillae, and are here recognized as a separate species, L. montana . Quantitatively L. montana differs from L. hexasepala in its larger leaves, notably in its longer petioles (mean length 59.7 cm versus 32.0 cm) and wider middle segments (mean width 6.2 cm versus 2.3 cm).

Subspecific variation:—One specimen (Henderson 3688) has an unusually long costa.

Figures

FIGURE 14. Distribution maps of L. kontumensis, L. magalonii, L. manglaensis, and L. montana.

FIGURE 15. Type of L. montana (Henderson & Bui Van Thanh 3689).