Oreocharis hapii K.S.Nguyen, Aver. & C.W.Lin

Nguyen, Khang Sinh, Averyanov, Leonid V. & Lin, Che Wei, 2024, Oreocharis hapii (Gesneriaceae), a new species from central Vietnam, Phytotaxa 652 (3), pp. 235-240 : 236

Oreocharis hapii K.S.Nguyen, Aver. & C.W.Lin , sp. nov. ( Figs. 1 & 2 )

Type: — VIETNAM. Quang Nam Province: Dai Loc District, Dai Hong Commune , Ngoc Thach Village , Huu Nien Mountain , 5 January 2024, Truong Hoang Hap , QN-DL 01 (holotype: HN!, isotypes: HN!, LE!).

Diagnosis: — Oreocharis hapii somewhat resembles O. cotinifolia in having elliptical foliage, campanulate corolla tube, and stamens protruding from the tube. However, the new species differs from O. cotinifolia in a stoloniferous habit (vs. absent stolons), petioles and stems densely woolly (vs. villous), curved scabrous hairs on the adaxial surface of the leaf blade (vs. villous), sub-actinomorphic corolla (vs. distinctly zygomorphic) that is white (vs. pink), with 4 stamens (vs. 2).

Description: —Perennial, rosette, monoecious herbs. Stem very short, stout, 3–5 mm thick; internodes congested; nodes forming stolons up to 11 cm or longer, ca. 3 mm thick, densely pale yellowish-brown woolly. Petioles terete, grooved adaxially, 2–15 mm long, 1.8–2.5 mm thick, densely pale yellowish-brown woolly. Leaves 6–10, decussate, spirally arranged, congested at the apex of stem; leaf blade subcoriaceous, elliptic to widely elliptic or suborbicular, 16–33 × 15–27 mm, at base rounded, obtuse to subcordate, apex obtuse to rounded, margin entire, revolute with rows of subappressed white scabrous hairs; adaxially emerald green to dusky yellowish-green, densely curved with white scabrous hairs having inflated base; abaxially pale yellowish-green, covered with curved white scabrous, densely pale yellowish-brown woolly hairs and sparsely white scabrous along veins; secondary veins pinnate,3–5 on each side of midrib, slightly impressed adaxially and conspicuously prominent ribs abaxially. Inflorescences 1–3 on one stem, axillary, simple, cymose, subumbel-like, each 1–3-flowered; peduncles 4–6 cm long, ca. 0.5 mm thick; erect, maroon to blackish-purple, sparsely appressed white scabrous and pale golden-brown woolly; bracts 2, linear to oblanceolate, 1.7–4.5 × 0.3–0.8 mm, adaxially subappressed white scabrous, abaxially densely pale yellowish-brown woolly, margin entire; pedicels 1.3–3.4 cm long, sparsely subappressed white scabrous and pale yellowish-brown woolly. Calyx equally 5-lobed, free to base; lobes lanceolate to narrowly triangular, 1.7–2.2 × 0.8–1 mm, brownish-purple to maroon, abaxial and margin sparsely subappressed white scabrous; apex obtuse. Corolla sub-actinomorphic, white, inside light green at the base and emerald green patches between lobes in the corolla throat; glabrous on both surfaces except that the inside of the tube; tube campanulate, 3–4.5 mm long, 4–5.5 mm in diameter, abruptly constricted at base; lobes subequal, ovate, elliptic to suborbicular, or widely obovate, 6–11 × 5–10 mm, apex obtuse to rounded, margin entire, ciliate. Stamens 4, anthers free, filaments white, filiform, with very sparse gland-tipped trichomes on the upper twothirds and dense on the lower one-third; filaments of upper pair 3–5 mm long, adnate at 1.2–1.8 mm from the base of corolla tube; filaments of lower pair 5–7.5 mm long, adnate at 1.5–2.1 mm from the base of corolla tube; anthers reniform, yellow, 0.8–1.3 mm long, bsifixed, glabrous; staminode 1, adnate ca. 1 mm above corolla tube base, small, capitate, ca. 0.2 mm long. Disc 0.5–0.8 mm in height, margin undulate to shallowly lobed, glabrous. Pistil 10–12 mm long; ovary 5–7.5 mm long, ca. 1.2 mm in diam., glabrous; style 3–5 mm long, ca. 0.5 mm in diam., glabrous; stigma bilobed, T-shaped, lobes ca. 1 mm long. Capsules narrowly fusiform, straight, ca. 23 × 1.4 mm, glabrous, loculicidal.

Distribution and ecology:— The new species is currently only found in its type locality in Dai Loc District, Quang Nam Province, central Vietnam, where it grows on wet or humid rock, on shaded, steep slopes of sandstone mountains covered by evergreen broad-leaved forest at elevation of 400–600 m a.s.l. The plant flowers in December to January, and fruits expectedly from January to April.

Etymology: —The specific epithet refers to the name of its discoverer, Mr. Truong Hoang Hap. The Vietnamese name “Nhạc ngựa hạp” is proposed.

Conservation status: —Only one population of Oreocharis hapii with less than 700 mature plants was currently discovered at Huu Nien Mountain, Ngoc Thach Village, Dai Hong Commune, Dai Loc District, Quang Nam Province. These days, this population remains undisturbed by agricultural activities and has not been exploited for ornamental purposes. Meanwhile, the area of the species occurrence is not officially protected and may be affected by negative anthropogenic influence in the future. According to available data the conservation status of the new species may be provisionally assessed as Vulnerable (VU: D1) following criteria proposed by the IUCN Red List Categories and Criteria Version 16 (IUCN, 2024).

Notes: —The new species exhibits a range of distinctive morphological characters, notably a sub-actinomorphic corolla with a campanulate tube and elongated stamens. These characteristics bear resemblance to three Chinese species, including Oreocharis benthamii var. reticulata , O. cotinifolia , and O. dayaoshanioides . A comparison of O. hapii with these three phenetically similar species is presented in Table 1 .

Figures

FIGURE 1. Oreocharis hapii K.S.Nguyen, Aver. & C.W.Lin. A. Habit; B, B'. Portion of leaf, adaxial and abaxial surfaces; C. Portion of petiole; D. Bract; E. Opened corolla, showing stamens and staminodes; F. Corolla, lateral view; G–G'''. Stamens; H. Pistil, also showing disc; I. Opened disc; J. Calyx lobes; K. Stigma; L. Capsule.

FIGURE 2. Oreocharis hapii K.S.Nguyen, Aver. & C.W.Lin. A. Habit and habitat; B. Habit; C. Juvenile leaves; D. Portion of leaf,adaxial surface, E. Same, abaxial surface; F. Corolla, front, dorsal and lateral views; G. Opened corolla; H. Bracts; I. Style and stigma, also showing an stamen; J. Calyx lobes; K. Pistil; L. Filaments and corolla inside; M. Old capsule. Photo A by Truong Hoang Hap; Photos B–M from QN-DL 01 by K.S. Nguyen.