Lanonia honheoensis Henderson & Nguy

Henderson, Andrew & D ựng, Nguy ễn Qu ốc, 2022, A revision of Lanonia (Arecaceae, Coryphoideae, Livistoninae), Phytotaxa 532 (3), pp. 209-245 : 230-232

11. Lanonia honheoensis Henderson & Nguy ễn Quốc Dựng sp. nov. Type:— VIETNAM. Khanh Hoa province, Ninh Hoa district, Tien Du commune, Hon Heo mountain , 12.450N 109.233E, 334 m, 6 July 2010, A. Henderson & Bui Van Thanh 3672 (holotype HN!, isotype NY!). Fig. 12 .

Stems 1.0 m long, 3.0 cm diameter, clustered. Leaves 8; ligules 5.0 cm long, soon disintegrating into fibers; sheaths and proximalmost part of petioles with scattered, brown scales; petioles 50.0 cm long, 0.7 cm wide at the apex; petiole thorns usually poorly developed, brown or black, more or less regularly arranged on proximalmost part of petiole; hastulas flat, rounded, not infolded; leaf blades 58.0 cm wide; costas 8.0 cm long, narrow, with a pulvinus at the apex abaxially, with the numerous segments free to the base except the middle pair joined at their bases; segments 15 per leaf, not mottled, with minute, reddish-brown scales abaxially, with (on dried specimens) straight margins; middle segments 37.5 cm long, 8.7 cm wide at the apex; apices of middle segments with adaxial splits much deeper than abaxial ones. Inflorescences 110.0 cm long; prophylls and peduncles length not recorded; rachis bracts flattened, splitting apically and laterally, almost woody and scarcely tomentose; rachillae not filiform nor thick and ribbed, sparsely to moderately covered with short, mostly simple, brownish hairs; staminate rachises length not recorded; staminate partial inflorescences 4, branched to 4 orders; staminate rachillae 58, 10.0 cm long, 0.6 mm diameter; staminate flowers not recorded; pistillate rachises absent; pistillate partial inflorescences 1, branched to 3 orders; pistillate rachillae on proximalmost partial inflorescence 12, length and diameter not recorded; pistillate flowers length and styles not recorded; fruits size not recorded, globose, color not recorded, with smooth surfaces; seeds not recorded.

Distribution and habitat:—Southern Vietnam in Khanh Hoa province on Hon Heo in dry forest on limestone soils at 334 m elevation ( Fig. 10 ).

Taxonomic notes:— Two specimens formerly included in Lanonia poilanei (see notes under that species) differ by their middle segments with the apices with adaxial splits much deeper than abaxial ones (versus not much deeper), and are here recognized as a separate species, L. honheoensis . Quantitatively the two species differ in the considerably longer inflorescences of L. honheoensis ; 110.0 cm long versus 70.0 cm long.

Figures

FIGURE 10. Distribution maps of L. hainanensis, L. hexasepala, L. honbaensis, and L. honheoensis.

FIGURE 12. Type of L. honheoensis (Henderson & Bui Van Thanh 3672).