Ceropegia antoanensis Luu, H.C.Nguyen, T.B.Tran

Nguyen-Le, Xuan Bach, Nguyen, Hieu Cuong, Tran, The Bach & Luu, Hong Truong, 2025, Ceropegia antoanensis (Apocynaceae: Ceropegieae), a new species from Vietnam, Phytotaxa 682 (3), pp. 295-300 : 296-298

Ceropegia antoanensis Luu, H.C.Nguyen, T.B.Tran & X.B. Nguyen-Le, sp. nov. ( Fig. 1 )

Diagnosis: —The new species is most morphologically allied to Ceropegia ansariana Murugesan & A.A. Mao in Murugesan & Mao (2021: 122) but it differs from latter by having a combination of the following characteristics: 9.5–10.3 (vs. ca. 15 in C. ansariana ) mm long petioles, glossy and adaxially glabrous (vs. adaxially and minutely pubescent) leaf laminas, a glabrous (vs. pubescent) peduncle, linear-lanceolate (vs. lanceolate) bracts, a strongly (vs. slightly) curved corolla tube, 5–6 (vs. 6–9) mm wide corolla lobes that are inside basally white, centrally maroon, and apically green (vs. greenish or yellowish-green with clear greenish reticulate veins at base), 2.5 (vs. 0.7–1.0) mm long lobes of the outer series that are almost as long as those in the inner series (vs. double the length), 0.65–0.9 (vs. 0.25) mm long caudicles and orange to yellow (vs. pinkish-reddish) pollinia.

Type:— VIETNAM. Binh Dinh Province, An Lao District, An Toan Commune, An Toan Nature Reserve , coordinates 14°31’28”N 108°41’28”E, 763 m elevation, 15 November 2021, Luu Hong Truong, Nguyen Le Xuan Bach , Nguyen Quoc Dat & Nguyen Hieu Cuong BN 070 (Holotype: SGN! {barcode SGN005637 }; Isotypes: SGN! { SGN005638 , SGN005639 }, HN!, PHH!, HNU!) ; 18 November 2024, Nguyen Hieu Cuong Cu-2024-060 (Paratypes: SGN! { SGN007384 , SGN007385 , SGN007386 , SGN007387 }, PHH!, VNMN!) .

Perennial, twining herb. Tubers ovoid, ca. 1 cm long, ca. 1 cm in diameter, fleshy, cream. Roots fibrous and/or adventitious, white, fleshy, 4–10 cm long, 0.5–1 mm in diameter. Stems slender, terete, glabrous, green, usually branched, 2.0– 2.5 mm in diameter, internodes (5) 6–9.3 cm long. Leaves simple, opposite; petiole 9.5–10.3 mm long, 1.1–1.6 in diameter, channeled above, glabrous; lamina linear-lanceolate, 5–8 cm long, 1.0– 1.6 cm wide, base obtuse to rounded, apex acuminate, entire at margins, discolorous, adaxially dark green, glossy glabrous, occasionally setose above and along the margins, abaxially light green, glabrous; venation: pinnate, middle vein adaxially slightly depressed, abaxially prominent; secondary veins 6–8 pairs, brochidodromous, spacing increasing toward base, obscure when fresh; colleters 2 at base of adaxial lamina, elliptical, 250 μm long, 200 μm wide. Inflorescences one per node, extra-axillary, umbellate, 1–8-flowered, with 1 flower open at a time; peduncles 2–13 mm long, 1.5–2 mm in diameter, greenish, glabrous; pedicels curved, 10–20 mm long, 1.5–1.6 mm in diameter, greenish, glabrous; bracts 2 at base of pedicel, linear-lanceolate, 1.5–2.5 mm long, dark purple, green, apex acute, glabrous. Calyx 5-lobed; lobes linear-lanceolate, 4.7–5.1 mm long, 0.6 mm wide, greenish from base to dark purple towards apex, glabrous, with acuminate apex. Corolla tubular, 4–4.6 cm long, strongly curved; tube 2.7–3.0 cm long, dilated at base, 6.5–7.7 mm long, 6–7 mm in diameter, then narrowing into a tube of ca. 10 mm long x 2.5 mm in diameter and gradually widening upwards, mouth 9.6–12.6 mm in diameter; outside glabrous, white at base, turning greenish upward, pale green at mouth, brown streaked and blotched; inside glabrous, dark purple on lower half, pale greenish white with longitunal veins on upper half; corolla lobes 5, narrowly triangular, folded, 13–19 mm long, 5–6 mm wide; outside greenish with purple streaks or blotches; inside basally white, centrally maroon, apically green, with dense white 1–2 mm long trichomes and connate tips, apical part glabrous or sparsely. Corona biseriate, 4–4.5 mm in diameter, cream at base; outer series of 5 deeply bifid lobes, lobules narrowly triangular, c. 2.5 mm long, 0.4 mm wide at base, dark purple at base, turning cream towards apex, covered with white ca. 1 mm long trichomes; inner series of 5 flattened lobes, erect, linear, lobes 3–3.5 mm long, 0.4–0.5 mm wide, dark purple blotched at base, turning cream towards apex, glabrous, with rounded apex. Pollinaria 5, with 2 pollinia per pollinarium, 450 μm long, 260 μm in diameter, erect, ovoid, orange when fresh, yellow when dry, inner angle with a prominent translucent margin, with 65–90 μm long caudicles; corpusculum clavate, reddish when fresh, brown when dry, 200 μm long, 95 μm in diameter. Ovary conical in pairs, 2.4 mm long, 0.6 mm wide at the base, greenish, dark purple blotched, glabrous, apex acute; ovules numerous, white, on marginal placentation. Follicles fusiform, paired, 13–17 cm long, 2.5–3 cm in diameter. Seeds flat, 7–9 mm long, 1.3–2 mm wide, brown; coma 3–6 cm long, silky white.

Etymology:— The species epithet is derived from the location where the new taxon was discovered.

Vernacular name:— Lồng đèn An Toàn (Vietnamese).

Phenology:— Flowering and fruiting seen from November to December.

Distribution and ecology:— The species is known only from An Toan Nature Reserve (Binh Dinh Province, Vietnam). It grows at forest edges along a stream at elevations above 700 m a.s.l.

Proposed IUCN conservation status: — Data Deficient ( IUCN Standards and Petitions Subcommittee 2024). The species was found in a small population of fewer than 10 mature individuals. Its habitat, located near farmland, is highly susceptible to human disturbance. Urgent conservation measures are necessary to protect this species and its habitat.

Note:— The new plant is morphologically closest to C. ansariana as both species have linear-lanceolate leaves and umbellate inflorescences. However, C. antoanensis differs from C. ansariana in many characteristics: it has 9.5– 10.3 (vs. 15 mm) long petioles, glossy and adaxially glabrous (vs. adaxially and minutely pubescent) leaf laminas, linear-lanceolate (vs. lanceolate) bracts, a strongly curved (vs. slightly curved) corolla tube that is externally basally white and apically greenish with brown streaks or blotches (vs. greenish with purplish maroon streaks or blotches) and internally pale greenish white with green lines (vs. greenish or yellowish white with red or maroon lines) on the upper half, corolla lobes that are 5–6 (vs. 6–9) mm wide, outside basally white and apcially greenish with brown streaks or blotches (vs. greenish or yellowish-green with purplish maroon streaks and blotches) and inside basally white, centrally maroon and apically green (vs. basally greenish or yellowish-green, apically greenish or yellowish green), long corona lobes (2.5 vs. 0.7–1.0 mm long in outer series, 3–3.5 vs. 2–2.7 mm long in inner series), 0.65–0.9 (vs. 0.25) mm long caudicles and orange (vs. pinkish-reddish) pollinia.

The general appearance of its leaves and inflorescences in C. antoanensis may call that in C. khasiana Murugesan, A.A.Mao, Meitei & Kambale in Murugesan et al. (2019: 520) but the latter is easily distinguishable by having two 12–18-flowered inflorescences per node with two bracts and two flowers open at a time, greenish-pinkish, sparsely pubescent and 10–25 mm long peduncle, externally purplish flowers with pinkish white streaks or blotches, slightly curved corolla tubes that are pinkish white with red lines on the upper half, 20–22 mm long corolla lobes with apical part glabrous without, 1–1.2 mm long (outer series) to 2–2.5 mm long (inner series) corona lobes, 0.25 mm long caudicles and yellowish pollinia.

In summary, our new plant is morphologically distinct from these two species by its unique combination of characteristics: a glabrous peduncle, a strongly curved corolla tube, corolla lobes with three distinct, clearly separated color zones on the inside, and corona lobes of the outer series that are almost as long as those in the inner series. Detailed morphological differences among the compared species are shown in Table 1.

Figures

FIGURE 1. Ceropegia antoanensis. A. Part of the plant; B. Roots; C. Tuber; D. Leaf blades, adaxial and abaxial; E. Colleters; F. Inflorescence; G. Bracts; H. Flower; I. Longitudinal section of flower; J. Corolla lobes, side view and top view; K. Calyx; L. Corona, top view; M. Corona, side view; N. Pollinarium; O. Ovary; P. Follicles; Q. Seed.