Vanilla cardinalis Aver. & Nuraliev, 2022

V. Averyanov, Leonid, Nuraliev, Maxim S., Thai, Tran Huy, Maisak, Tatiana V., Popov, Eugene S., Lyskov, Dmitry F., Kuznetsov, Andrey N. & Kuznetsova, Svetlana P., 2022, Vanilla cardinalis (Orchidaceae, Vanilloideae), a new red-lipped species from southern Vietnam, Phytotaxa 548 (1), pp. 119-125 : 120-124

Vanilla cardinalis Aver. & Nuraliev , sp. nov. ( Figs. 1 , 2 )

Diagnosis:—The new species is most similar to Vanilla sumatrana , but differs in distinctly smaller flowers, narrowly obovate sepals and petals, bright bloody red lip, half circular, flabellate, deeply emarginate median lobe of lip, central callus with scarious bristles, and lip apex with numerous soft flexuose hairs 4–5 mm long.

Type:— VIETNAM. Phu Yen Province: Song Hinh District, Song Hinh Municipality, Song Hinh Protected Forest , forest along Ea Nhe River bank, epiphytic, 12°48’18’’N E 109°01’08’’E, elev. 250 m, 11 June 2021, E. S. Popov, s.n. (holotype LE01077952 https://en.herbariumle.ru/?t=occ&id=124854) .

Authentic photos:— VIETNAM. Phu Yen Province: Song Hinh District, Song Hinh Municipality, Song Hinh Protected Forest , forest along river bank, epiphytic, 12°48’18’’N 109°01’08’’E, elev. 250 m, 18 May 2020, S. P. Kuznetsova, A. N. Kuznetsov, s.n. ( LE01122901 https://en.herbariumle.ru/?t=occ&id=99529); same location, 16 January 2021, M. S. Nuraliev, D. F. Lyskov, NUR 3151 ( LE01093251 https://en.herbariumle.ru/?t=occ&id=124858) .

Etymology:—The species name refers to bright bloody red colour of the lip.

Description:— Epiphytic creeping vine, generally glabrous. Stem fleshy, green, unbranched or sparsely branched, (4)5–7(8) mm in diameter; internodes (6)7–9(10) cm long; aerial climbing roots attached at stem nodes, 1–1.5 mm in diameter. Leaves shortly petiolate; petiole (3–)4(–5) mm long, (6–)7(–8) wide when flattened, with upcurved winged margins; leaf blade fleshy, glossy green, narrowly obovate or narrowly elliptic, shortly acuminate at apex, (8)10–14(16) cm long, (3)4–5(6) cm wide. Inflorescence axillary, subsessile; peduncle (0.8)1–1.5(2) cm long, bearing 2–4 triangular, cymbiform sterile bracts; rachis pendulous, fleshy, green, slightly sigmoidally curved, (3)4–8(9) cm long, (5)6–7(8) mm in diameter, with numerous spirally arranged flowers. Floral bracts spreading, fleshy, green, broadly triangular, slightly cucullate, obtuse at apex, (2.5)3–5(6) mm long, (2.5)3–3.5(4) mm wide. Pedicel and ovary green, pure white near base, slightly curved, terete, 3–4 cm long. Flowers (1.5)2–7(9) mm apart, opening successively, widely opened, 3.8–4.2 cm across; sepals and petals uniformly light greenish yellow; lip with ground colour light yellowish, heavily marked with bright bloody red blotches and bright bloody red along veins, with pure white bunch of bristles on central callus and hairs at lip apex. Dorsal sepal somewhat fleshy, narrowly obovate, concave, obtuse at apex, (2.4)2.5–2.6(2.7) cm long, (0.7)0.8–1(1.1) cm wide. Lateral sepals somewhat fleshy, narrowly obovate, slightly oblique, concave, obtuse at apex, (2.5)2.6–2.8(2.9) cm long, (0.8)0.9–1(1.1) cm wide. Petals thinner textured than sepals, narrowly obovate, blunt to almost rounded at apex, (2.4)2.5–2.6(2.7) cm long, (0.9)1–1.1(1.2) cm wide, abaxially with prominent keel along the median vein. Lip trumpet-shaped, 3-lobed, (2.3)2.4–2.6(2.7) cm long, (2.6)2.7–2.8(2.9) cm wide (when flattened), erose, wavy and crispate along margin; side lobes half circular, 5–6 mm long, 8–10 mm wide; median lobe half circular, flabellate, 7–8 mm long, 14–16 mm wide, deeply emarginate; basal margins adnate to the column sides for (10)11(12) mm, forming a tubular structure; adaxial lip surface almost smooth, with 3(or 5) inconspicuous toothed longitudinal ridges along the median line, at center with oblong callus 4 mm long bearing a bunch of numerous dense scarious backwards pointing bristles 3.5–4 mm long; lip apex between lobules of median lobe with a bundle of numerous soft flexuose, somewhat fleshy hairs 4–5 mm long. Column white with yellowish tint, slender, slightly incurved towards apex, 1.2–1.4 cm long; lateral sides of clinandrium with forward directed acute stelidia; rostellum rectangular, truncate at front; anther cap helmet-shaped, shallowly bifid at apex, 2 mm long and wide. Pollinarium consists of two half-notched, narrowly obovoid pollinia 2 mm long. Ripening fruits fleshy, cylindrical, slightly curved, 7–10 cm long, 0.8–1.2 cm in diameter.

Ecology and phenology:—Primary and old secondary lowland evergreen, broad-leaved forest at elevation of about 250 m a.s.l., along river bank. Flowers in (April) May–June.

Distribution:— Vietnam, Phu Yen Province (Song Hinh District). Endemic of southern Vietnam in limits of the eastern coastal part of the South Indochinese floristic province ( Averyanov & Averyanova 2003, Fu et al. 2019); known from a single location.

Conservation status:—Estimated as critically endangered: CR (B1, B2a, C1, D). Our field studies and observations indicate that V. cardinalis meets the following IUCN (2019) Red List criteria: only one population is discovered with extent of occurrence less than 100 km 2 (B1) and area of occupancy less than 10 km 2 in one known location (B2a), the population includes less than 250 mature individuals with estimated decline of their number at least on 25% in 1 generation (C1), and population is very small with estimated number of mature individuals less than 50 (D).

Notes:—We assign Vanilla cardinalis to V. subgen. Xanata Soto Arenas & Cribb (2010: 358) sect. Tethya Soto Arenas & Cribb (2010: 359) . Within this section, the new species belongs to the so-called V. kinabaluensis group (sensu Soto Arenas & Cribb 2010), together with such Vietnamese species as V. siamensis and the recently described V. atropogon and V. tiendatii ( Schuiteman et al. 2013, Nguyen et al. 2020). Species of this group share such diagnostic features as broadly elliptic leaves, terete stems, multi-flowered racemose inflorescences, stout ovary, thick and relatively short fruit, uniformly greenish-yellow tepals, and lip cuneate-flabellate, trumpet-shaped, not unguiculate, more or less trilobed, with recurved median lobe bearing bunch of fleshy hairs or long fleshy papillae. This group is distributed from S China to New Guinea, with the highest species diversity in Indonesia ( Soto Arenas & Cribb 2010).

Vanilla cardinalis is morphologically distinct from all the species of the genus known in eastern Indochina ( Cambodia, Laos and Vietnam) and is unlikely to be closely related to any of them. Among the species of V. subgen. Xanata sect. Tethya , the new species is similar to V.sumatrana J.J. Smith (1920: 22) , also a member of the V.kinabaluensis group, and V. griffithii Reichenbach (1854: 88) belonging to the V. griffithii group ( Soto Arenas & Cribb 2010). In particular, the three species share a trilobed lip with emarginate median lobe. Vanilla cardinalis is most close to V. sumatrana endemic to Sumatra ( Smith 1920, Comber 2001), but differs from the latter in smaller flowers, narrowly obovate (vs. broadly oblanceolate) sepals and petals, median lobe of lip half circular, flabellate, 7–8 mm long, 14–16 mm wide, deeply emarginate (vs. oblong narrowly ovate, 6.7 mm long, 7.5 mm wide, with very shortly bilobed apex), central callus bearing dense bunch of numerous scarious bristles (vs. bearing several thin imbricate scarious transverse plates), lip apex between lobules of median lobe with a bundle of numerous soft flexuose, somewhat fleshy hairs 4–5 mm long (vs. median lobe at center with a cushion covered with dense short hairs 1–2 mm long), lip almost entirely bright bloody red (vs. with dark purple veins). Detailed comparison of the two species is presented in the Table. It is noteworthy that the new species is readily recognized among almost all the species of V. sect. Tethya by its small flowers and predominantly red lip.

Vanilla cardinalis is similar to Miguelia cruenta , Vanilla atropogon and V. yersiniana in being a very rare local endemic of the eastern part of the South Indochinese floristic province ( Averyanov et al. 2003, Fu et al. 2019). The only known location of the new species obviously requires protection to assure conservation of this remarkable plant.

Figures

FIGURE 1. Vanilla cardinalis. A. Sterile portion of stem. B. Leaf, adaxial surface. C. Rachis of inflorescence. D. Inflorescence and immature fruits. E. Flower, half side view. F. Flower buds, views from different sides. G. Flattened sepals, petals and column. H. Petals, adaxial (left) and abaxial (right) surface. I. Flattened lip, adaxial surface. J. Sagittal section of lip and column. K. Flattened lip, side view. L. Central part of lip (adaxial surface) with central callus, side view. M. Column, views from different sides. N. Anther cap and pollinia. Compiled from Popov, s.n. (F–N), Kuznetsova, Kuznetsov, s.n. (D, E), and Nuraliev, Lyskov, NUR 3151 (A–C); correction and plate design by L. Averyanov and T. Maisak.

FIGURE 2. Vanilla cardinalis. A. Flowering plant. B. Apical portion of inflorescence with flower, side view. C. Flower, half side view. D. Flattened sepals, petals, lip and column. E. Flattened lip, adaxial, abaxial and side view. F. Central callus, side view. G. Column, front, half side, and side views. H. Anther cap and pollinarium. I. Pollinarium. Drawn by L. Averyanov and T. Maisak from Popov, s.n., Kuznetsova, Kuznetsov, s.n., and Nuraliev, Lyskov, NUR 3151.