Circumscription and phylogenetic position of Ligularia sect. Stenostegia (Asteraceae: Senecioneae) based on morphological, cytological, and molecular phylogenetic evidence,TAXON

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Circumscription and phylogenetic position of Ligularia sect. Stenostegia (Asteraceae: Senecioneae) based on morphological, cytological, and molecular phylogenetic evidence
TAXON ( IF 3.0 ) Pub Date : 2020-08-25 , DOI: 10.1002/tax.12280
Chen Ren _{1,

2} , Long Wang ₁ , Irina D. Illarionova ₃ , Qin‐Er Yang _{1,

2}

Affiliation

Ligularia sect. Stenostegia (Asteraceae: Senecioneae) has been questioned about its monophyly and phylogenetic position in our previous study. To settle the dispute, we here verify the phylogenetic pattern of L. sect. Stenostegia with a much denser taxon sampling in the section. The results have corroborated our previous hypothesis, by showing that L. sect. Stenostegia is monophyletic only after excluding L. lancifera, and that the core L. sect. Stenostegia is more closely related to Parasenecio and Sinacalia than to Ligularia. The relationships are further supported by evidence from morphology and geographical distribution, and the results of cytological studies and statistical topology tests in this study. The core L. sect. Stenostegia, with the absence of expanded leaf sheaths and a base chromosome number of x = 30, is substantially different from Ligularia, while congruent with Parasenecio and Sinacalia. Its concentrated distribution in eastern Central Asia also readily sets it apart from Ligularia, which is mainly distributed in eastern Asia, with the center of species diversity in the Himalayas and the Hengduan Mountains region in southwestern China. In contrast, L. lancifera has greatly expanded leaf sheaths, a chromosome number of 2n = 58, and a distribution in eastern Xizang (Tibet) in China, all perfectly matching the features of Ligularia. The AU and SOWH statistical topology tests also strongly favor this phylogenetic hypothesis, by significantly rejecting the alternative hypotheses in current classification. Based on all the evidence, L. lancifera is excluded from L. sect. Stenostegia, and the core L. sect. Stenostegia is segregated as an independent genus of its own, with a new name Vickifunkia.

更新日期：2020-10-06

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