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| Heterostemma cucphuongense T.B.Tran & Rodda
in Tran, Han, Hai, ... et Rodda. 2020.
Photographs by N.Q. Dat, T.B. Tran, Thuong V.A.
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Abstract
Heterostemma cucphuongense (Apocynaceae, Asclepiadoideae), a new species from Vietnam is described, illustrated and compared with the similar species Heterostemma succosum Kerr. Heterostemma cucphuongense differs from H. succosum by the morphology of the rachis of the inflorescence, the margins of the corolla lobes and the colour of the adaxial surface of the corolla.
Keywords: Ceropegieae, Cuc Phuong National Park
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| Figure 1. Heterostemma cucphuongense T.B.Tran & Rodda A flowering branch B flower, view from above (adaxial) C flower, from underneath D corona, from above E ovary F pollinarium.
(Photographs by N.Q. Dat, T.B. Tran, Thuong V.A., photo edit by M. Rodda)
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Heterostemma cucphuongense T.B.Tran & Rodda, sp. nov.
Diagnostic characters: This new species is similar to H. succosum Kerr, as both species have shortly pedunculate inflorescences, on which the flowers open in gradual succession (with generally a single flower open) and have relatively large rotate flowers (generally > 14 mm diam.). They are separated by the presence of a distinct rachis that develops in the inflorescence (which is absent in H. succosum); the margins of the corolla lobes are revolute (vs. flat in H. succosum), the pedicels are shorter (5–10 mm, vs. 15–30 mm in H. succosum) and by the colour of the adaxial surface of the corolla (red with white-yellow spots vs. yellow-orange with reddish-brown spots in H. succosum).
Etymology: The species is named after the type locality, Cuc Phuong National Park, in Ninh Binh Province, northern Vietnam.
Distribution and ecology: Heterostemma cucphuongense was only collected once, near one of the main trails in the Cuc Phuong National Park. It was found in primary evergreen forest on soils derived from degraded limestone. It was collected in flower in June.
The Bach Tran, Le Ngoc Han, Do Van Hai, Bui Hong Quang, Nguyen Thi Thanh Huong, Bui Thu Ha, Tran Van Hai and Michele Rodda. 2020. Heterostemma cucphuongense (Apocynaceae, Asclepiadoideae), A New Species from Vietnam. PhytoKeys. 148: 119-124. DOI: 10.3897/phytokeys.148.50029
