Ophiorrhiza liuyanii L. Wu, Y. H. Tan & K. S. Nguyen, 2024

Liu, Chu-Yu, Liao, Xiao-Wen, Ye, Li-Chun, Tan, Yun-Hong, Nguyen, Khang Sinh, Thien, Tran Duc & Wu, Lei, 2024, Ophiorrhiza liuyanii (Rubiaceae), a new species from south-western China and northern Vietnam, PhytoKeys 248, pp. 199-206 : 199-206

Ophiorrhiza liuyanii L. Wu, Y. H. Tan & K. S. Nguyen sp. nov.

Figs 1 , 2 A – K

Type.

China • Yunnan Province: Menghai County, Mengsong Village , growing along a stream or on moist slopes under densely evergreen broad-leaved forests, 21°30'37.36"N, 100°30'17.33"E, elevation 1715 m, 13 Apr 2024 (fl.), X. W. Liao LXW 0217 (holotype: CSFI!; isotypes: CSFI!) .

Diagnosis.

Morphologically similar to O. alatiflora and O. baviensis , but the new species differs from the former by its congested (vs. developing) inflorescences and infructescences, broad-ovate to ovate (vs. linear or linear-lanceolate) bracts, 4–11 (vs. 0.8–1.5) mm wide and from the latter by its glabrous (vs. densely pubescent or puberulent) peduncles, broad-ovate to ovate (vs. lanceolate) bracts, corollas tube inside with (vs. without) a ring of white hairs at the middle in long-styled flowers.

Description.

Perennial herbs, erect or ascending at the base, up to 80 cm tall; stem, leaves, petiole, stipule, bract, outside flower and capsule glabrous. Leaves generally in equal pairs (usually isophyllous); petioles 1–3 cm, pale green; leaf blades drying papery, dark green adaxially, pale green abaxially, elliptic, oblong or ovate-elliptic, 7–15 × 3–6 cm, cuneate at base, acuminate at apex, margins entire; secondary veins 9–13 at each side; stipules small, broadly triangular, ca. 1 mm long, caducous, with glands at the inner base. Inflorescences congested cymose, many-flowered, drooping at the early stage, then erect; peduncles 1–2 cm long, pale green; bracts broad-ovate to ovate, 9–22 × 4–11 mm, apex acuminate, acute or sometimes obtuse. Flowers heterostylous; pedicels to 3 mm long, puberulent. Calyx puberulent; hypanthium oblate, 1.5–1.8 × 1.8–2.2 mm; lobes triangular to ovate triangular, 0.8–1.6 mm long, acuminate at apex. Corolla white or pinkish-white, subtubular; tube 1.0– 1.6 cm long, outside longitudinally winged from apex to base, wings straight or undulate, ca. 0.8–2 mm wide; lobes 5, ovate-triangular, 3.8–4.8 × 2.8–3.5 mm, inside pubescent, apex acute, slightly incurved. Stamens 5; anthers linear, 2.2–3.2 mm long. Stigma bilobed; ovary 2 - celled. Long-styled flowers: inside with a ring of white hairs at the middle of the corolla tube and puberulent from the middle up to the throat; stamens included, positioned a little below the middle of the corolla tube; style 8–12 mm long, densely pubescent; stigma positioned at the corolla throat, lobes elliptic, ca. 1.8 mm long. Short-styled flowers: sparsely pubescent at the middle of the corolla tube; stamens reaching slightly beyond corolla throat, not exserted; style 3.8–5.5 mm long, pubescent; stigma lobes lanceolate, ca. 2.8 mm long. Capsules mitriform, ca. 4.5 × 10 mm.

Phenology.

Flowering from April to May; fruiting from May to July.

Distribution and habitat.

Ophiorrhiza liuyanii is currently known from south-western China (Menghai County of southern Yunnan Province) and north-western Vietnam (Dien Bien Province). It grows along streams or moist places under evergreen broad-leaved forests at an elevation range from 1500–1850 m, in which the vegetation is dominated by the tree families Lauraceae , Fagaceae , Magnoliaceae , Theaceae and Betulaceae , shrub families Ericaceae and Symplocaceae and herbaceous families Urticaceae , Balsaminaceae and Begoniaceae .

Preliminary conservation status.

Our field surveys revealed that three populations of Ophiorrhiza liuyanii have a total of matured individuals of ca. 5000 plants. The population of the holotype locality is the largest and is in good condition because their occupied area is included in the Nabanhe River Watershed National Nature Reserve and, during our 10 yearly re-visitation, we found the habitats had been well-protected. Therefore, the new species is preliminarily assessed as Least Concern (LC) according to IUCN (2023).

Etymology.

The species epithet is named after Prof. Yan Liu, Guangxi Institute of Botany, Guangxi Zhuangzu Autonomous Region and the Chinese Academy of Sciences, who has made great contributions to plant taxonomy in China.

Chinese name.

宽翅蛇根草 (kuan-chi-she-gen-cao).

Additional specimens examined

(paratypes). China • Same village as holotype, elevation 1700 m, 2 Apr 2001 (fl.) H. Wang 4311 ( PE 2014155 !) , elevation 1500 m, 7 Jun 2014 (fr.), L. Wu 3706 ( BNU! CSFI!), 21°30'42.43"N, 100°30'18.73"E • elevation 1700 m, 13 Apr 2024 (fl.), X. W. Liao LXW 0219 ( CSFI!), 21°30'27.65"N, 100°30'27.12"E • elevation 1695 m, 13 Apr 2024 (fl.), X. W. Liao LXW 0220 ( CSFI!) .

Vietnam • Dien Bien Province: Muong Nhe Distr., Muong Nhe Natural Reserve, Sin Thau Municipality , Ta Mieu Village , around point 22°24'02"N, 102°08'38"E, elevation 1800–1850 m, old humid secondary evergreen broad-leaved montane forest of very steep mountain slopes composed of sandstone, terrestrial herb to 0.5 m tall, flower pinkish-white, common, 14 May 2022, L. Averyanov, H. T. Tran, K. S. Nguyen, H. C. Nguyen, T. Maisak, C. K. Bac, VR 1637 ( HN!, LE!) .

Notes.

Ophiorrhiza liuyanii is morphologically most similar to O. baviensis on having congested inflorescences and distinct, persistent bracts. However, the former differs from the latter mainly by its glabrous (vs. pubescent or puberulent) stems, peduncles and calyx (Figs 2 B, C, D, E , 3 E, F ), broad-ovate to ovate (vs. lanceolate) bracts with larger in size, 9–22 × 4–11 (vs. 6–15 × 2–7) mm (Figs 2 D – F , 3 C, D, G ), corolla tubes inside with (vs. without) a ring of white hairs at the middle and anthers positioned near the middle (vs. base) in long-styled flowers (Figs 2 H, I , 3 E, F ). The new species also resembles O. alatiflora by having wings longitudinally and wider than 0.8 mm outside corolla, but it clearly differs by its congested (vs. developing) inflorescences and infructescences (Figs 2 B, D, E, J, K, M, N ), broad-ovate to ovate (vs. linear or linear-lanceolate) bracts, 4–11 (vs. 0.8–1.5) mm wide (Figs 2 F, J, K, N ). Further distinctive characteristics of the three species are shown in Table 1 .

Figures

Figure 1. Ophiorrhiza liuyanii A flowering branch B stipule C longitudinally dissected short-styled flower D longitudinally dissected long-styled flower E infructescence in side view. Drawn from the holotype by M. M. Cheng.

Figure 2. Ophiorrhiza liuyanii A habitat B habit C stipule D inflorescence in side view E inflorescences in different development stages F bracts from lower part to upper part of inflorescence G corollas in top view H longitudinally dissected long-styled flower I longitudinally dissected short-styled flower J infructescence in side view K infructescence in top view. Ophiorrhiza alatiflora L habit M inflorescence in lateral view N infructescence. Scale bars: 1 cm. Photos by L. Wu, X. W. Liao and K. S. Nguyen.

Figure 3. Ophiorrhiza baviensis A habit B inflorescence in top view C, D inflorescence in side view E longitudinally dissected long-styled flower F longitudinally dissected short-styled flower G infructescence in top view. Scale bars: 1 cm. Photos by L. Wu.