Research Paper

Two new species of Pentasacme (Apocynaceae, Asclepiadoideae) from Yunnan, China

Cheng Liu, Xiao-Jian Hu, Jin-Ping Zhang, Wen-Bin Yu, Yun-Hong Tan

Published on: 08 June 2022

Page: 326 - 334

DOI: 10.6165/tai.2022.67.326

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2022 vol.67 no.3 pp.326-334

Abstract

Pentasacme malipoense C. Liu & Y.H. Tan and P. tubulosum C. Liu, X.J. Hu & Y.H. Tan are two new species from Yunnan, China, which are described and illustrated in this study. Molecular phylogenies using the nrITS, rps16 and trnT-F datasets support these two new species formed a clade in the genus Pentasacme, then as the sister to P. caudatum, which is the only Chinese species hitherto included in phylogenetic studies. Pentasacme tubulosum can be clearly distinguished from the other five recognized species of this genus by its tubular corolla and tube much longer than lobes. Pentasacme malipoense is characterized by having campanulate and deeply lobed corolla, tube much shorter than lobes, corolline coronas present and inverted conical style-head, which is remarkably different from its sister species P. tubulosum. In addition, P. malipoense differs from P. caudatum by the reddish pedicels and calyces, oblong-lanceolate corolla lobes, staminal coronas present and inverted conical style-head, and from P. wallichii and P. shanense by its lanceolate leaf blades, reddish pedicels and calyces, both corolline coronas and staminal coronas present, purple-red anther appendages and inverted conical style-head. Furthermore, for illustrating the two species, diagnostic characters, photographs, morphological descriptions, distribution, and habitat are also provided, as well as the geographical distribution and the diagnostic key to all recognized species of Pentasacme.

Keyword: Apocynaceae, Pentasacme caudatum, P. malipoense, P. shanense, P. tubulosum, P. wallichii, Yunnan, China

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