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| Xanthophytum antoanense Luu, H.C.Nguyen, X.B.Nguyen-Le & Q.D.Nguyen, in H. C. Nguyen, X. B. Nguyen-Le, Q. D. Nguyen, T. Q. T. Nguyen et Luu, 2024. |
Abstract
Xanthophytum antoanense is described as a new species endemic to Central Vietnam. It is morphologically closest to X. capitatum in having setose hairs on the abaxial leaf surface and a pedunculate head-like inflorescence but differs from the latter by a number of characteristics: shorter stem, 3-lobed stipules, narrowly lanceolate leaf blades with a cuneate-oblique base and 20–22 pairs of secondary veins, 3.5–4.5 cm long peduncle, spatulate calyx lobes, larger corollas with a 5–5.4 mm long tube and 2.4–3 mm long lobes, and an apically hairy style. A detailed description, an illustration, and information on distribution, ecology and phenology, and a provisional assessment of the conservation status of the new species are provided.
Key words: An Toan Nature Reserve, Central Vietnam, endemic, head-like inflorescence, indumentum, setose
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| Xanthophytum antoanense A plant in situ B whole plant C leaf base D leaf, adaxial surface E leaf, abaxial surface F setose hairs on abaxial leaf surface (dried) G stipule H inflorescences I bracts (dried) J flower, top view K calyx lobes L opened corolla showing stamens M pistil N ovary, disc and base of style O flower, side view, with an interfloral bract (arrow) P corolla and calyx, some calyx lobes removed Q anthers R stigma (corolla removed) S cross-section of ovary. |
Xanthophytum antoanense Luu, H.C.Nguyen, X.B.Nguyen-Le & Q.D.Nguyen, sp. nov.
Diagnosis: The new species is morphologically closest to X. capitatum Valeton but differs from the latter by its 3-lobed (vs. unlobed) stipules, narrowly lanceolate (vs. oblong to obovate) leaf blades with a cuneate-oblique (vs. symmetrically cuneate to attenuate) base and 20–22 (vs.11–16) pairs of secondary veins, 3.5–4.5 (vs. 0.5–3) cm long peduncle, spatulate (vs. bluntly triangular) calyx lobes, larger flowers with a 5–5.4 (vs. c. 1.8) mm long corolla tube and 2.4–3 (vs. c. 0.7) mm long corolla lobes, and an apically hairy (vs. glabrous) style.
Hieu Cuong Nguyen, Xuan Bach Nguyen-Le, Quoc Dat Nguyen, Tran Quoc Trung Nguyen and Hong Truong Luu. 2024. Xanthophytum antoanense (Rubiaceae, Ophiorrhizeae), A New Species from Vietnam. PhytoKeys. 250: 215-222. DOI: doi.org/10.3897/phytokeys.250.137482
