Lanonia dasyantha (Burret) Henderson & Bacon (2011: 890)

Henderson, Andrew & D ựng, Nguy ễn Qu ốc, 2022, A revision of Lanonia (Arecaceae, Coryphoideae, Livistoninae), Phytotaxa 532 (3), pp. 209-245 : 225

5. Lanonia dasyantha (Burret) Henderson & Bacon (2011: 890) .

Licuala dasyantha Burret (1941: 334) . Type:— CHINA. Guangxi, Lungtschou , 10 July 1939, S. Ko 55448 (the holotype at B was destroyed). Neotype (designated here):— CHINA. Guangxi, Longchuan County, Daqing Shan , 800 m, May 28, 1991, Yuzong Wei 201491 (neotype IBK n.v., IBK image!).

Stems 0.9(0.3–1.5) m long, 6.0(2.1–10.0) cm diameter, solitary or clustered. Leaves 15 per stem; ligules 10.0(5.0– 15.0) cm long, soon disintegrating into fibers; sheaths and proximalmost part of petioles with scattered, brown scales; petioles 105.6(50.0–200.0) cm long, 0.5(0.2–0.8) 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 84.2(20.0–107.0) cm wide; costas 14.1(8.5–24.0) 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 8(5–12) per leaf, mottled, with minute, reddish-brown scales abaxially, with (on dried specimens) straight margins; middle segments 37.0(16.5– 54.5) cm long, 9.3(5.0–14.0) cm wide at the apex; apices of middle segments with adaxial splits not much deeper than abaxial ones. Inflorescences 39.1(23.5–60.0) cm long; prophylls 4.3(3.5-5.0) cm long; peduncles 16.7(15.0–18.3) cm long; rachis bracts flattened, strongly ribbed, splitting apically and laterally and tattering along the ribs; rachillae thick and ribbed, densely covered with much branched, brownish-white hairs; staminate rachises not recorded; staminate partial inflorescences 1–3, branched to 2 orders; staminate rachillae 3(3–4), 14.4(11.0–18.2) cm long, 1.4(0.8–1.9) mm diameter; staminate flowers 3.5 mm long; sepals not pedicellate at the base, densely hairy; petals with a narrowed apex, solid internally; 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 1–2 orders; pistillate rachillae on proximalmost partial inflorescence 2(1–4), 19.1(8.5–30.5) cm long, 3.0(1.8–3.4) mm diameter; pistillate flowers 4.5 mm long, with elongate styles; fruits 9.9(7.9–13.6) mm long, 7.6(5.8–9.5) mm diameter, ellipsoid, red, reddish, or bright red, with uneven, ridged surfaces; seeds with a curved basal intrusion.

Distribution and habitat:— Southern China in Guangxi and Yunnan provinces and northern Vietnam in Bac Kan, Ha Giang, Lao Cai, Nghe An, Phu Tho, Quang Ninh, Thanh Hoa, Tuyen Quang, and Vinh Phuc provinces in lowland rainforest, usually on limestone soils, at 528(100–1,150) m elevation ( Fig. 9 ).

Taxonomic notes:— Specimens determined as preliminary species Lanonia dasyantha share a unique combination of qualitative variable states and are therefore recognized as a phylogenetic species. The holotype at B was destroyed and an isotype, supposedly at SYS, has not been found (Lixiu Guo, pers. comm.). Therefore a neotype is designated.

Lanonia dasyantha has noticeably shorter prophylls than other species, and pistillate flowers are closely spaced along the rachillae and consequently the fruits are closely packed on the infructescence. The precise localities of several specimens, especially older ones from northeast Vietnam and Yunnan in China are not known. One specimen (Tsang 29436) appears to be mixed and is here excluded. Lanonia dasyantha appears similar to L. acaulis and L. verrucosa , sharing with those species ellipsoid fruits with uneven, ridged surfaces.

Subspecific variation:— Lanonia dasyantha occurs to the northwest and northeast of the Red River in Vietnam ( Fig. 9 ). Specimens from the two areas differ significantly from each other in two variables (petiole length, number of segments) (t –test, P <0.05), with specimens from the northeast having lower values. In particular, two specimens ( Atha 84, Harder 4141) from the same locality in Lang Son province in Vietnam appear noticeably smaller than others and have thinner rachillae. Rachillae of these specimens are scored as thick and ribbed, even though they are thinner. There are too few data on rachillae thickness (and other inflorescence variables) to test for differences.

Figures

FIGURE 9. Distribution maps of L. dasyantha, L. gialaiensis, and L. gracilis.