Lanonia honbaensis Henderson & Nguy

Henderson, Andrew & D ựng, Nguy ễn Qu ốc, 2022, A revision of Lanonia (Arecaceae, Coryphoideae, Livistoninae), Phytotaxa 532 (3), pp. 209-245 : 229

10. Lanonia honbaensis Henderson & Nguy ễn Quốc Dựng sp. nov. Type:— VIETNAM. Khanh Hoa province, Dien Khanh district, Hon Ba Nature Reserve , 12.116N 108.933E, 1,445 m, 11 July 2010, A. Henderson, Bui Van Thanh & Nguyen Thi Bich Ngoc 3705 (holotype HN!, isotype NY!). Fig. 11 .

Stems 2.3(1.5–4.0) m long, 3.5(2.5–5.0) cm diameter, solitary. Leaves 13; ligules 20.8(15.0–26.5) cm long, papery, not disintegrating into fibers; sheaths and proximalmost part of petioles with dense, flat, black scales; petioles 77.5(60.0– 90.0) cm long, 0.6(0.6–0.7) 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 raised, triangular, infolded; leaf blades 55.0(50.0– 60.0) cm wide; costas 3.8(2.0–5.7) cm long, triangular, with a pulvinus at the apex abaxially, with the numerous segments free almost to the base; segments 16(13–19) per leaf, mottled or not mottled, with minute, reddish-brown scales abaxially, with (on dried specimens) straight margins; middle segments 30.3(26.0–35.0) cm long, 7.1(3.7–11.1) cm wide at the apex; apices of middle segments with adaxial splits much deeper than abaxial ones. Inflorescences 60.0 cm long; prophylls 15.0 cm long; peduncles 38.0 cm long; rachis bracts flattened, splitting apically and laterally, usually densely brown tomentose; rachillae not filiform nor thick and ribbed, sparsely to moderately covered with short, mostly simple, brownish hairs; staminate inflorescences not recorded; pistillate rachises absent; pistillate partial inflorescences 1, branched to 2–3 orders; pistillate rachillae on proximalmost partial inflorescence 14(6–19), 12.4(10.2–15.5) cm long, 1.1(1.0–1.2) mm diameter; pistillate flowers length not recorded, with short styles; fruits not recorded; seeds not recorded.

Distribution and habitat:— Southern Vietnam in Khanh Hoa province, known only from Hon Ba Nature Reserve, in montane rainforest at 1,512(1,445 –1,578) m elevation ( Fig. 10 ).

Taxonomic notes:— Four s pecimens formerly included in Lanonia hexasepala (see notes under that species) differ from others by their raised, triangular, infolded (versus rounded) hastulas, and are here recognized as a separate species, L. honbaensis . Although staminate inflorescences and fruits are not recorded, L. honbaensis differs quantitatively from L. hexasepala and has considerably higher mean values for all recorded variables.

Figures

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

FIGURE 11. Type of L. honbaensis (Henderson et al. 3705).