Lanonia kontumensis Henderson & Nguy

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

12. Lanonia kontumensis Henderson & Nguy ễn Quốc Dựng sp. nov. Type:— VIETNAM. Kon Tum province, Kon Plong district, Hieu commune, a few km south on Ho Chi Minh highway from road 24, ca. 1,000 m, 14.598N 108.417E, 23 April 2013, A. Henderson & Nguyễn Qu ốc Dựng 3872 (holotype VFM!, isotype NY!). Fig. 13 .

Stems 0.7(0.3–1.0) m long, 2.4(2.0–2.7) cm diameter, solitary or clustered. Leaves 8(5–10) per stem; ligules 5.1(3.0– 6.5) cm long, soon disintegrating into fibers; sheaths and proximalmost part of petioles with scattered, brown scales; petioles 88.8(55.0–120.0) cm long, 0.5(0.4–0.5) cm wide at the apex; petiole thorns usually poorly developed, brown or black, more or less regularly arranged on proximalmost part of petiole; hastulas raised, triangular, infolded; leaf blades 72.0(64.0–80.0) cm wide; costas 2.8(1.8–4.5) cm long, triangular, with a pulvinus at the apex abaxially, with the numerous segments free almost to the base; segments 17(14–21) per leaf, not mottled, with minute, reddish-brown scales abaxially, with (on dried specimens) ruffled margins; middle segments 37.8(34.0–42.5) cm long, 2.4(1.3–4.2) cm wide at the apex; apices of middle segments with adaxial splits not much deeper than abaxial ones. Inflorescences length not recorded; prophylls 14.5(13.5–15.5) cm long; peduncles length not recorded; rachis bracts flattened, splitting apically and laterally, usually densely brown tomentose; rachillae filiform, sparsely to moderately covered with short, mostly simple, brownish hairs; staminate rachises absent; staminate partial inflorescences 1, branched to 3 orders; staminate rachillae 35(26–43), 9.1(7.2–11.0) cm long, 0.8(0.7–0.9) mm diameter; staminate flowers 1.5 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 3–4 orders; pistillate rachillae on proximalmost partial inflorescence 35(29–40), 13.2(9.7–16.0) cm long, 1.2(1.0–1.4) mm diameter; pistillate flowers 2.0 mm long, with short styles; fruits and seeds not recorded.

Distribution and habitat:— Southern Vietnam in Gia Lai and Kon Tum provinces in montane rainforest at 1,193(1,000 –1,380) m elevation ( Fig. 14 ).

Taxonomic notes:— Specimens formerly included in Lanonia centralis (see notes under that species) differ from others by their segments with ruffled margins (versus segment margins not ruffled), filiform rachillae with short, mostly simple, brownish hairs (versus non- filiform rachillae with wooly, much branched, reddish-brown hairs), and stamens with alternately long and short filaments and small, almost square anthers (versus stamens with equal filaments and longer, rectangular anthers), and are here recognized as a separate species, L. kontumensis . Quantitatively it differs from L. centralis by its shorter stems, shorter ligules, and shorter and narrower segments.

By its high elevation habitat and single staminate and pistillate partial inflorescences, L. kontumensis appears more like L. hexasepala and similar species.

Subspecific variation:—The two specimens from Ngoc Linh are geographically isolated from the others and are somewhat different in their wider segments.

Figures

FIGURE 13. Type of L. kontumensis (Henderson & Nguyễn Quốc Dựng 3872).

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