Lanonia honheoensis Henderson & Nguy

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 View FIGURE 12 GoogleMaps .

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 View FIGURE 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.