Yan Liu ophiorrhiza (Ophiorrhiza liuyanii) from China and Vietnam similar to O. alatiflora and O. baviensis

NEWS - Prof. Yan Liu ophiorrhiza (Ophiorrhiza liuyanii L.Wu, Y.H.Tan & K.S.Nguyen, sp. nov.), from southwest China and northern Vietnam which is morphologically similar to Ophiorrhiza alatiflora and Ophiorrhiza baviensis was concluded as a new species after more than 10 years of investigation.

Ophiorrhiza Linnaeus is an Indo-Malesian genus of Rubiaceae distributed in tropical and subtropical Asia with only a few extending to Australia, New Guinea and the Pacific Ocean. The total species number of the genus is unclear and is estimated to be around 200-300 species due to the lack of revision worldwide.

China has a diversity of Ophiorrhiza with about 74 taxa. Most of them are in southern and southwest China, especially in Guangxi and Yunnan. In 2013, researchers found an unusual specimen and tentatively considered it as O. baviensis Drake.

In a recent field survey in Menghai County, southwest Yunnan, a strange plant of this species was observed bearing fruit in 2014 and flowering in 2024 and was recollected. After careful examination of fresh and dried material, they concluded that this plant is a new taxon.

O. liuyanii is a perennial herb, erect or ascending at the base, up to 80 cm tall; stem, leaves, petiole, stipules, bracts, 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.

Bilobed stigma; 2-celled ovaries. 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.

The new species is morphologically similar to O. alatiflora and O. baviensis, but has dense inflorescences (vs. developed in O. alatiflora) and numerous fruits, bracts broad-ovate to ovate (vs. linear or linear-lanceolate), 4–11 (vs. 0.8–1.5) mm wide

The new species has glabrous pedicels (vs. densely pubescent or puberulent in O. baviensis), bracts broad-ovate to ovate (vs. lanceolate), corolla tube deep with (vs. without) a central ring of white hairs in long-styled flowers.

O. liuyanii flowers in April–May and fruits in May–July. It is currently known from southern Yunnan (southwestern China) and Dien Bien (northwestern Vietnam). It grows along streams or moist places under evergreen broadleaf forests at elevations of 1500–1850 m. Vegetation is dominated by Lauraceae, Fagaceae, Magnoliaceae, Theaceae, Betulaceae, Ericaceae, Symplocaceae, Urticaceae, Balsaminaceae and Begoniaceae.

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).

Original research

Liu C-Y, Liao X-W, Ye L-C, Tan Y-H, Nguyen KS, Thien TD, Wu L (2024). Ophiorrhiza liuyanii (Rubiaceae), a new species from south-western China and northern Vietnam. PhytoKeys 248: 199-206, DOI:10.3897/phytokeys.248.135078

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