Listera anthropophora Aver. & V.C.Nguyen

Averyanov, Leonid V., Nguyen, Van Canh, Vuong, Truong Ba, Nuraliev, Maxim S., Nguyen, Khang Sinh, Maisak, Tatiana V., Yudova, Daria A., Saidov, Nikita T., Nguyen, Cuong Huu & Nong, Duy Van, 2024, New orchids in the flora of Vietnam VIII (Orchidaceae: Epidendroideae, tribes Malaxideae, Neottieae and Podochileae), Phytotaxa 658 (1), pp. 1-49 : 3-4

Listera anthropophora Aver. & V.C.Nguyen , sp. nov.

( Fig. 1 & 2A )

Diagnosis: —The new species differs from the closest Listera yunnanensis in glabrous peduncle, hispid rachis, glabrous pedicels, broader sepals (1.4–1.6 mm wide) and petals (1–1.2 mm wide), entirely glabrous lip, side lobes of lip erect, spathulate, broadening towards apex, and column with anther prominently bent back at 90°.

Type: — VIETNAM. Lao Cai Province: Bat Xat District, evergreen broad-leaved forest at elevation of about 2500 m a.s.l., living plants collected by unknown collector in October 2023, type herbarium specimen prepared on 3 November 2023, Nguyen Van Canh, L. Averyanov, T. Maisak, AL 2439 (holotype LE LE 01253791! https://en.herbariumle.ru/?t=occ&id=212990, photos of plant used for preparation of the type herbarium specimen LE LE 01124550 https://en.herbariumle.ru/?t=occ&id=207739, drawing LE LE 01124776 https://en.herbariumle.ru/?t=occ&id=213009).

Description:—Herb terrestrial, autotrophic. Rhizome underground, thin, light brownish, glabrous, bearing a few distant, wiry, white roots. Stem erect, light greenish to almost white, terete, 26–32 cm tall (including inflorescence), 1.5–2 mm in diameter, glabrous, with 3–4 scarious thin tubular sheaths at base. Leaves 2, arranged at middle of stem, pseudo-opposite, sessile, grassy green adaxially, pale green to almost white abaxially, broadly ovate, 4.5–5.5 cm long, 3.5–4 cm wide, glabrous, base slightly cordate, apex acute or apiculate. Peduncle 7–8 cm long, glabrous, with 2 distant sterile bracts; bracts narrowly triangular, 5–16 mm long, glabrous, apex acuminate. Inflorescence a raceme; rachis 5–7 cm long, hispid, laxly 10–15-flowered; floral bracts narrowly triangular, as long as pedicels or slightly shorter, glabrous. Pedicel 4–4.5 mm long, glabrous, prominently bent upwards near the apex. Ovary fusiform, about 3 mm long, glabrous. Flowers widely opening, glabrous; sepals and petals spreading, indistinctly 1-veined. Median sepal narrowly ovate, 2.5–3 mm long, 1.4–1.6 mm wide, blunt to obtuse at apex. Lateral sepals narrowly ovate, somewhat oblique, 3–3.2 mm long, 1.4–1.6 mm wide, obtuse. Petals oblong, slightly oblique, as long as sepals, 1–1.2 mm wide, blunt to roundish at apex. Lip narrowly obovate in outline, 7.5–8.5 mm long, 2.5–3 mm wide, at base with side lobes, median lobe apex deeply 2-lobuled; side lobes directed towards lip base, erect, spathulate, broadened towards apex, 1.4–1.6 mm long, 0.4–0.5 mm wide; lobules of median lobe diverging at a sharp angle, narrowly triangular, slightly falcate inwards, acuminate to shortly caudate, 3.8–4.2 mm long; disk fleshy, at center with 2 short, low, fleshy keels, near base with 2 lateral fold-like teeth placed more proximally than side lobes. Column 0.8–1 mm tall on stalk 0.4–0.5 mm long; stigma orbicular; rostellum insignificant; anther narrowly ovoid, 0.4–0.5 mm long, bent back at 90°. Capsule narrowly obovoid, 6-ribbed, 6.5–7 mm long, 3.5–4 mm in diameter.

Etymology: —The species name refers to the anthropomorphic shape of the flower lip.

Habitat and phenology: —Terrestrial rhizomatous herb. Evergreen broad-leaved forest on granite at elevation of about 2500 m a.s.l., on wet mossy ground. Very rare. Flowers likely in August–September.

Distribution: —Endemic to NW Vietnam (Lao Cai Province: Bat Xat District).

Conservation status: — Listera anthropophora is known from a single location. Taking into consideration the very small area of its expected occurrence and extensive selected logging in this area, we estimate the conservation status of this species as globally Critically Endangered (CR) following the formal criteria proposed by the IUCN (2024): A2a,b; B1a,b(i–iii)+2a,b(i–iii); C1+2(i,ii). In details, we estimate (within the statements employed by the IUCN):—expected population reduction for 10 years or 3 generation ≥ 80% is not reversible (A2), based on direct observation (a) and observed decline of the area of occupancy, extent of occurrence and habitat quality (b);—the area of occurrence <100 km ² (B1) and the area of occupancy <10 km ² (B2), with 1 known population (a) and continuing observed decline of extent of occurrence (bi); the area of occupancy (bii); area, quality of habitat (biii);—the number of mature individuals <250, estimated or projected continuing decline in 25% in 3 years or 1 generation (C1), and observed, estimated, projected or inferred continuing decline when the number of mature individuals in each subpopulation (C2(i)) ≤ 50 and 90–100% of mature individuals in one subpopulation (C2(ii)).

Notes: — Listera anthropophora is morphologically very close to Listera yunnanensis S.C. Chen (1981: 759 , see also Chen et al. 2009), but distinctly differs from the latter species in shorter stem 26–32 cm (vs. 37–47.5 cm) tall, glabrous (vs. pubescent) peduncle, rachis 5–7 cm long, hispid, 10–15-flowered (vs. rachis 14–16 cm long, pubescent, 24–35-flowered), glabrous (vs. sparsely pubescent) pedicel, broader sepals (1.4–1.6 mm vs. 1–1.3 mm wide) and petals (1–1.2 mm vs. 0.5–0.6 mm wide), entirely glabrous lip (vs. lip minutely ciliate along the margin), side lobes of lip erect, spathulate, broadening to the apex, 1.4–1.6 mm long, 0.4–0.5 mm wide (vs. side lobes horizontally or down directed, ovate-oblong, tapering to the apex, about 1.3 mm long, 0.6 mm wide), disk with 2 short, low, fleshy keels (vs. disk with 2 swollen, suborbicular lamellae), and anther prominently bent back at 90° (vs. anther erect to suberect). The prominent erect spathulate side lobes of lip broadened towards the apex is a unique feature that is unknown from all the other species of the genus.

Figures

FIGURE 1. Listera anthropophora. A. Fruiting plant. B. Portion of rachis. C. Flattened flower, front view (lip removed). D, E. Lip from lower (D) and upper part (E) of inflorescence. F. Column, front view. G. Column, side view. All drawn from the type specimen L. Averyanov et al., AL2439 by L. Averyanov.

FIGURE 2. A. Listera anthropophora. Photos by L.Averyanov from living plant prior to the preparation of the type herbarium specimen Nguyen Van Canh et al., AL2439. B–E. Bulbophyllum conchiferum. Photos by L. Averyanov from the specimen L. Averyanov, Nguyen Van Canh, AL2080. F–I. Bulbophyllum reclusum. Photos by L. Averyanov from the specimens L. Averyanov et al., AL1904 (F, G) and AL2721 (H, I). Photo correction and design by L. Averyanov.