Supplementary description.
Plant perennial, dioecious. Stems subterranean, up to 9.0 cm long, elliptic in cross-section, 0.7–2.0 × 0.3–1.5 cm, solitary. Leaves 6 (3–8); ligules 8.0 (7.0–9.0) cm long, papery, not disintegrating into fibers; sheaths and proximalmost part of petioles with scattered, brown scales; petioles 32.4 (6.5–85.0) cm long, 0.2 (0.1–0.3) cm wide at the apex; petiole thorns absent; hastulas raised, triangular, infolded; leaf blades 59.7 (18.0–85.0) cm long, 33.0 (5.0–54.0) cm wide; costa 3.5 (0.4–11.0) cm long, relatively short or long and narrow, with a pulvinus at the apex abaxially, with the few segments free and the central pair free to the base or joined at their bases or borne on a 0.7 (0.3–1.0) cm long petiolule, or 28.8 (17.0–51.0) cm long, continuous to apex of leaf, without an abaxial pulvinus; segments variable in number among individuals, from undivided to variously divided up to nine segments, not mottled, with minute, reddish-brown scales abaxially; central segments undivided to variously divided into bifid segments to pinnately segmented of up to five segments on each side, 20.9 (10.0–33.5) cm long, 1.8 (0.4–3.2) cm wide at the apex in split ones, 30.8 (17.0–52.0) cm long, 3.7 (2.0–5.0) cm wide at the apex in undivided ones, wider or not wider than the lateral segments; apices of central segments with adaxial splits not much deeper than abaxial ones. Inflorescences interfoliar, sexually dimorphic, with staminate and pistillate inflorescences conspicuously differing in rachilla number; peduncular bracts absent, rarely one in pistillate inflorescence; rachis bracts narrowly tubular, splitting apically, sparsely tomentose; rachillae filiform, densely covered with lepidote, reddish-brown hairs; staminate inflorescence reduced to a single partial inflorescence or with two partial inflorescences, branched to 2–4 orders, 38.8 (23.7–59.0) cm long; prophyll 9.5 (4.6–17.0) cm long; peduncle 10.5 (7.0–16.0) cm long; rachises absent or 18.0 (10.0–24.0) cm long; rachillae 8 (3–12), 7.7 (5.5–10.5) cm long, 0.1 mm in diameter, purple; flowers solitary or two per cluster, 1.5 (1.0–1.8) mm long, ca. 2.9 mm in diameter; calyx 3-lobed, dark purple, sepals not pedicellate at the base, densely hairy; corolla comprising three triangular petals, dark purple, apex acute; stamens six, with short filaments fused proximally into a staminal ring, and small, almost square anthers; pistillodes three; pistillate inflorescence reduced to a single partial inflorescence, rarely two, branched to 1–2 orders, 30.7 (10.0–44.0) cm long; prophyll 7.3 (2.7–12.0) cm long; peduncles 9.6 (3.7–15.0) cm long; rachises usually absent, rarely 10.5 (7.5–13.5) cm long; rachillae 2 (1–3), 7.5 (4.3–10.8) cm long, 0.1 mm in diameter, purple; flowers solitary, 2.4 (2.0–2.6) mm long, ca. 3.9 mm in diameter; calyx 3-lobed, dark purple, densely hairy; corolla comprising three triangular petals, dark purple, apex acute; vestigial stamens six, with short filaments fused proximally into a staminodial ring; gynoecium apocarpous, carpels three. Fruits 12.0 (9. 0–13.0) mm long, 10.5 (8.0–11.0) cm wide, ellipsoid, red at maturity, with uneven surfaces in immature stage and smooth surfaces at full maturity; Seeds 8.5 (8.0–9.0) mm in diameter, globose, with a short, straight but asymmetrical basal intrusion.
Additional specimens examined.
China • Guangxi Zhuang Autonomous Region, Fangchenggang City, precise locality withheld, elevation 50 m a.s.l., growing in the understory of montane evergreen broad-leaved forest, 29 April 2026, Jia-Wei Qin & Zhi-Ling Tian, QJW-GXFC 260429 (HNNU!); • ibid., elevation 900 m a.s.l., 30 April 2026, Jia-Wei Qin & Zhi-Ling Tian, QJW-GXFC 260430 (HNNU!).
Taxonomic notes.
During field investigations along the Sino-Vietnamese border in 2024, a peculiar palm population was discovered. It could not initially be confirmed whether it represented one or multiple distinct species because of its remarkably wide variation in leaf morphology. After careful comparison of floral characters, the individuals with undivided and bifid leaves were verified to correspond to the species newly published in early 2026, L. yangchunensis. Individuals with undivided, bifid, quadrifid, and hexafid leaf forms were subsequently sampled for phylogenetic analysis. The results showed that all individuals with different leaf forms clustered into a single monophyletic clade (BP = 100, PP = 1.00) (Fig. 3). Combined with comparative morphological observations of inflorescences, the results confirmed that all these leaf forms belong to L. yangchunensis.
Multiple leaf morphotypes co-occur within each population in Guangxi and can be divided into three groups: the central segment undivided (including the undivided leaf form) (Fig. 5B), the central segment divided but without a petiolule (including the bifid leaf form) (Fig. 5C), and the central segment divided with a petiolule (Fig. 5D). One individual with a pinnate central segment (Fig. 5E) and another with a divided central segment but a continuous costa (Fig. 5F) were found to be exceptions. Furthermore, some mature individuals consistently produce asymmetric leaves, with unequal numbers of lateral segments on the two sides of the central segment.
Thus, the supplementary description is provided based on individuals from wild populations in Guangxi, China. All measurements were taken from mature wild individuals, excluding juvenile plants. This description supplements the range of morphological variation and newly recorded stable characters that were not covered in the original protologue based on a single population from Guangdong, China.