Polyalthia yingjiangensis sp. nov (Annonaceae) from the China/Myanmar border

During a field survey in Hongbenghe close to the China/Myanmar border in Yingjiang County, Yunnan Province, a new species was found and named Polyalthia yingjiangensis.

Polyalthia yingjiangensis sp. nov. is described from the China/Myanmar border. It is distinct in having outer petals that are much shorter than the inner petals and having a very long pedicel, perianth parts that are glabrous adaxially and pubescent abaxially, thicker and sparsely pubescent pedicels, as well as verrucose and darker monocarps(Figure).

During a field survey in Hongbenghe close to the China/Myanmar border in Yingjiang County, Yunnan Province, a species with leaves with a slightly asymmetrical leaf base, brochidodromous venation and reticulate tertiary veins, and hence referable to Polyalthia s.s. Molecular phylogenetic studies (not shown) also confirm its placement in Polyalthia. It is most similar to Polyalthia miliusoides I.M. Turner, a species known from Sabah and Brunei, in having outer petals that are much shorter than the inner petals and very long pedicels, i.e. characters which are rare in Polyalthia, but differs in having perianth parts that are densely hairy abaxially and glabrous adaxially, pedicels that are thicker and sparsely pubescent, as well as verrucose and darker monocarps. We believe that the plant represents a new species and describe it here as Polyalthia yingjiangensis. The new species Polyalthia yingjiangensis is named after its type locality, Yingjiang county of Yunnan province, China.

This work was financially supported by a grant from National Natural Science Foundation of China (grant no. 31400199) awarded to Bine Xue and a project of the Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences (Y4ZK111B01).The result published as "Polyalthia yingjiangensis sp. nov (Annonaceae) from the China/Myanmar border" on Nordic Journal of Botany. 

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Figure.  Flower and fruit morphology of Polyalthia yingjiangensis sp. nov. (A)–(E) branch and inflorescence, showing extra-axillary inflorescence with long pedicel, unequal corolla whorls and leaves with slightly asymmetrical leaf base with petiole superficially below lamina surface, (F) dried fruits (C. L. Dang 9977, YUKU), (G) a single dried monocarp, showing the verrucose surface (86 Exped. 01111, KUN), (H) lateral and top view of one seed, showing the shallow longitudinal circumferential groove (86 Exped. 01111, KUN), (I) transverse and longitudinal section of the seed, showing spiniform endosperm ruminations (86 Exped. 01111, KUN). Photos: (A)–(E) De-Ping Ye, (F)–(I) Bine Xue.