Lanonia eclipsata J. W. Qin & R. P. Kuang 2026, sp. nov.

Lanonia eclipsata J. W. Qin & R. P. Kuang sp. nov. Figs 1, 2 Type. Vietnam • Tuyen Quang Province, precise locality withheld, elevation 435 m a. s. l., on limestone hills, in evergreen broad-leaved forest, 23 April 2026, Jia-Wei Qin, QJW-VNTQ 260423 (holotype: ♀, HNNU!; isotypes: 3 ♂ 3 ♀, HITBC! HNNU!). Diagnosis. The new species differs from all other congeneric species by the combination of medium-sized plant, leaf blades 31.0–47.0 cm wide, ligules soon disintegrating into fibers, sheaths and proximalmost part of petioles with scattered, brown scales, rachillae filiform, without ribs, slender, 0.1–0.2 cm in diameter. Description. Plant perennial, dioecious. Stem decumbent, with the distal erect portion 40.3 (21.0–58.0) cm tall, 2.6 (2.0–3.0) cm in diameter, solitary. Leaves 10–20 per stem; ligules soon disintegrating into fibers; sheaths and proximalmost part of petioles with dense, brown scales; petioles 48.0 (33.0–78.0) cm long, 0.4–0.5 cm wide at the apex; petiole spines usually poorly developed, reddish-brown or brown, more or less regularly arranged on proximalmost part of petiole; hastulas raised, triangular, infolded; leaf blades 22.5 (20.0–25.7) cm long, 38.1 (31.0–47.0) cm wide; costa 5.1 (3.6–7.0) cm long, triangular, with a pulvinus at the apex abaxially, with the numerous segments free to the base; segments 9–16 per leaf, equal in size, strikingly mottled, with reddish-brown scales abaxially; central segments 22.5 (20.0–25.7) cm long, 6.4 (5.0–8.9) cm wide at the apex, not much 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 partial inflorescence and rachilla numbers; peduncular bracts usually absent, or rarely 1–2 in staminate inflorescences and 2–3 (– 4) in pistillate inflorescences; rachis bracts tubular, not strongly ribbed, splitting apically, usually densely reddish-brown tomentose distally; rachillae filiform, non-ribbed, densely covered with short, mostly simple, brownish hairs; staminate inflorescence 63.7 (34.5–100.0) cm long, with (1 –) 2–3 partial inflorescences, branched to (2 –) 3–4 orders; prophyll 5.7 (2.0–12.0) cm long; peduncle 13.1 (4.0–28.0) cm long; rachis 32.9 (17.0–51.0) cm long; rachillae 2–15 in the entire inflorescence, 17.5 (11.0–22.0) cm long, 0.1–0.2 cm in diameter, yellowish-green; flowers 2–4 per cluster, 2.5 (2.0–2.7) mm long, 2.4 (2.0–3.0) mm in diameter; calyx 3 - lobed, greenish-yellow, sepals not pedicellate at the base, densely hairy; corolla comprising three triangular-orbicular petals, greenish-yellow, apex acute; stamens six, with short filaments fused proximally into a staminal ring, and small, almost square anthers; pistillodes three, apocarpous; pistillate inflorescence reduced to a single partial inflorescence, branched to 1–2 orders, 75.0 (35.0–93.0) cm long; prophyll 5.4 (1.0–12.0) cm long; peduncle 41.5 (19.0–59.0) cm long; rachis absent; rachillae 1–2 (– 3), 14.3 (9.0–21.0) cm long, 0.1–0.2 cm in diameter, yellowish-green; flowers solitary, 2.5 (2.0–3.0) mm long, 2.9 (2.3–3.5) mm in diameter; calyx 3 - lobed, greenish-yellow, densely hairy; corolla comprising three triangular petals, greenish-yellow, apex rounded; vestigial stamens six, with short filaments fused proximally into a staminodial ring; gynoecium apocarpous, carpels three. Fruits ca. 0.9 cm long, ca. 0.9 cm in diameter, globose, red at maturity, with smooth surfaces; seeds ca. 0.5 cm long, ca. 6 mm in diameter, globose, with a straight but slightly asymmetrical basal intrusion. Etymology. The specific epithet refers to the distinctive foliar pattern of this species, whose leaves bear multiple concentric partial yellow arcs, each reminiscent of a partial solar eclipse. Phenology. Flowering from April to May, fruit maturation between August and September. Distribution and habitat. Lanonia eclipsata is only known from Tuyen Quang Province, Vietnam. It grows on limestone hills along riverbanks, in the understory of primary evergreen broad-leaved forest (Fig. 1 A, B), at elevations ranging from 400 m to 500 m a. s. l. Precise locality coordinates are withheld to protect this karst endemic species from uncontrolled exploitation. Taxonomic notes. Lanonia eclipsata is closely allied to L. dasyantha, especially given the considerable morphological variability exhibited by the latter. In vegetative characters, leaf blades of L. eclipsata are no more than 50 cm in diameter (Fig. 3: A 1), and stems are solitary. In contrast, L. dasyantha bears leaf blades up to 100 cm in diameter (Fig. 3: A 2) and is usually caespitose. However, juveniles of L. dasyantha often possess smaller leaves and a single stem, a morphology highly similar to that of L. eclipsata (Figs 3, 4). Nevertheless, the two taxa differ markedly in reproductive characters. The inflorescences of L. eclipsata are equal to or slightly longer than the leaves, spreading, erect, or becoming pendulous under their own weight (Figs 3: B 1, 4: A 1); those of L. dasyantha curve down below the leaves (Figs 3: B 2, 4: A 2). The sepals and petals of L. eclipsata are yellowish-green; the rachillae are yellowish-green and covered with reddish-brown hairs (Figs 3: C 1, 4: B 1). In L. dasyantha, sepals and petals are purplish-red, and the rachillae are purplish-red, densely covered with brownish-white hairs (Figs 3: C 2, 4: B 2). Fruits of L. eclipsata are not closely arranged on the infructescence; immature fruits are green, and mature fruits have smooth surfaces without ridges (Fig. 4: E 1, E 2). By comparison, fruits of L. dasyantha are closely packed in the infructescence, red when immature, and mature fruits possess uneven, ridged surfaces (Fig. 4: E 2). Conservation status. Lanonia eclipsata is currently known only from a single locality in Tuyen Quang Province, northern Vietnam, growing on limestone hills along river banks in the understory of primary evergreen broad-leaved forest at elevations of 400–500 m a. s. l. Within an area of approximately 1 km 2, three subpopulations have been recorded, each comprising 150–250 individuals, yielding an estimated total population of 450–750 individuals. The species is subject to intensive collection for the ornamental plant trade, from which a continuing decline in the number of mature individuals is inferred. Based on the known occurrences, the AOO is estimated at 4 km 2 (using the standard 2 × 2 km grid). While the raw EOO calculated from occurrence points is <100 km 2, the EOO is therefore set equal to the AOO at 4 km 2 following IUCN guidelines. Based on its extremely restricted geographic range, occurrence at a single location, and continuing decline, L. eclipsata is preliminarily assessed as Critically Endangered (CR) under the IUCN Red List Categories and Criteria as CR B 1 ab (v) + 2 ab (v), or CR B 1 ab (iii, v) + 2 ab (iii, v) if habitat quality decline is also accepted. Further surveys are recommended to better document the full distribution, population structure, and the magnitude of the decline.