Oreocharis caobangensis T.V.Do, Y.G.Wei & F.Wen, 2017

Do, Truong Van, Wei, Yi-Gang & Wen, Fang, 2017, Oreocharis caobangensis (Gesneriaceae), a new species from Cao Bang Province, northern Vietnam, Phytotaxa 302 (1), pp. 65-70 : 65-68

Oreocharis caobangensis T.V.Do, Y.G.Wei & F.Wen , sp. nov. ( Figs. 1 & 2 )

It is morphologically similar to Oreocharis lungshengensis (W.T. Wang 1975: 102) Mich.Möller & A.Weber (2011: 23) , but it differs from the latter in having petioles densely brownish villous (vs. densely white pubescent), lateral veins of leaf blade 6–8 pair (vs. 4–6 pairs), bracts smaller and only 1.5–2 mm long (vs. 4–9 mm long), corolla outside pubescent (vs. sparsely glandular puberulent), and pistil 18–20 mm long and glabrous (vs. (12–) 25–35 mm long and sparsely pubescent near apex).

Type: — VIETNAM. Cao Bang Province: Nguyen Binh District, Phia Oac-Phia Den National Park, on the trail to Phia Oac peak, 22°36 ′ 25.27 ″ N, 105°52 ′ 10.12 ″ E, elev. ca. 1570 m, 26 October 2013, T. V. Do 57 (holotype: VNMN!; isotype: IBK!) .

Perennial herb, acaulescent. Petiole 2–8 cm long, purple, densely brownish villous; leaf blade ovate to oblong-elliptic, 6–10.5 × 4–6 cm, adaxially densely appressed pubescent, dark-green, abaxially puberulent, base sometimes slightly oblique, broadly cuneate to nearly rounded, margin slightly serrate to crenate, apex acute; lateral veins 6–8 on each side of midrib, distinct, adaxially slightly sunken, abaxially clearly prominent. Cymes 3–4, 1–4-flowered; peduncle 3–6 cm long, pubescent; bracts 2, lanceolate to narrowly lanceolate, 1.5–2 × 0.2–0.5 mm, rust-brown villous, margin entire. Pedicel 0.5–1.5 cm long. Calyx divided to base, lanceolate to linear, 3–5 × 1.5–2 mm, brown, outside sparsely rust-brown villous, inside glabrescent, margin entire. Corolla purple, 1.5–3.2 cm long, outside pubescent; tube campanulatetubular, 10–25 × 3–10 mm; limb 2-lipped; adaxial lip 2-lobed from near base, abaxial lip 3-lobed, all 5 lobes obovate to suborbicular, nearly equal to each other, 4–9 × 4–12 mm. Stamens 4, adnate to corolla 6–12 mm above base; filaments slender, glabrous, 18–22 mm long, white; anthers oblong, 3–5 × 1.0– 1.2 mm, 2-loculed, dehiscing longitudinally, connective glabrous; staminode 1, 10–12 mm long, glabrous. Pistil 18–20 mm, greenish, glabrous; ovary 13–15 mm long; stigma 1, oval-shaped, ca. 1 mm long. Capsule oblong, glabrous, 2–3 cm long.

Etymology: —The specific epithet refers to Cao Bang Province in northern Vietnam where Oreocharis caobangensis was found. The type location of this new species is in Phia Oac-Phia Den National Park, a famous national park in Cao Bang Province.

Distribution, ecology and Phenology: — Oreocharis caobangensis is only known from the type locality in Phia Oac-Phia Den National Park, Cao Bang province, northern Vietnam. The species was found on humid soil in the shade, on damp rocks along streams in tropical evergreen forest at elevation of 1200–1600 m. This new species has been observed in flower from August to October, and in fruit from October and November.

Proposed IUCN conservation status:— Oreocharis caobangensis has been found in the well-protected corezone of Phia Oac-Phia Den National Park. Furthermore, this population is healthy and locally abundant with many young plants and seedlings growing in the area. Thus, it seems that this species is not at risk now, and it is proposed to be ‘Least Concern’ (LC) according to the IUCN Red List categories and criteria ( IUCN 2012).

Notes and taxonomic affinity:— The center of diversity of Orecharis is in the higher altitudinal areas of southwestern, southern, central and eastern China. Some species, especially those previously treated in Isometrum , can reach the southeastern Northwest China (e.g. Gansu Province). Oreocharis shows a wide range of diversity in morphology, for example, in leaf shape, cyme mode, and corolla form and color in above-mentioned regions. Oreocharis aurea covers an extensive region from Southwest China to North Vietnam ( Li & Wang 2004) and, before this new species was discovered, is the only one recorded and described in Vietnam. Another known species of Oreocharis in the Indo-China Peninsula is O. hirsuta Barnett (1961: 9) endemic to Thailand. Thus, not any sympatric species of Oreocharis can be found in the highland of northern Vietnam before. It is easy to distinguish them growing in Indochina Peninsula one by one by some special characters, i.e., corolla lobes are mostly shorter than the tube in O. aurea and O. hirsute , while those are just the opposite in O. caobangensis .

At a glance, the new species is similar to O. lungshengensis on shape of leaf blades and corolla, color of corolla, but some special characteristics in O. caobangensis (e.g. indumentum of petioles, number of lateral veins of leaf blade, size of bracts, indumentum of corolla outside, indumentum and length of pistil) indicate they are not the same. The fact that these two species share similar habitats suggests that the similarity in morphology might be the result of convergent evolution.

Figures

FIGURE 1. Oreocharis caobangensis. A. Habitat, B. Frontal view of corolla, C. Opened corolla showing stamens, D. Stamens (anthers and filaments) (D1 & D2: the filaments at the insertions of corolla inner), E. Pistil, F. Stigma (Drawn by Ms. Xuan Wen).

FIGURE 2. Oreocharis caobangensis. A Habit, B. Plant and cymes, C. Frontal and lateral view of corollas, D. Lateral view of cymes and corollas, E. Top view of corolla, F. Opened corolla showing stamens, G. Young fruits and fruit peduncle (Photographs by Fang Wen (A, C, D, E) and Do Van Truong (B)).