J Syst Evol ›› 2023, Vol. 61 ›› Issue (5): 748-763.DOI: 10.1111/jse.12915

• Research Articles • Previous Articles     Next Articles

Using phylogenomics to untangle the taxonomic incongruence of yellow-flowered Camellia species (Theaceae) in China

Su-Juan Wei1,2, Yong-Qing Liufu1,3, He-Wen Zheng1, Hai-Ling Chen4, Yan-Chi Lai1, Yan Liu4, Quan-Qing Ye1, and Shao-Qing Tang1*   

  1. 1 Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Ministry of Education, Guangxi Normal University, Guilin 541004, Guangxi, China;
    2 State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China;
    3 Guangxi Museum of Natural History, Nanning 530012, China;
    4 Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin 541006, Guangxi, China
    *Author for correspondence. E-mail:shaoqing@mailbox.gxnu.edu.cn
  • Received:2021-10-28 Accepted:2022-09-07 Online:2022-09-21 Published:2023-09-01

Abstract: All yellow Camellia plants in China are threatened, but their classification is contentious. Here, we performed a phylogenetic reconstruction based on nuclear double-digest restriction site-associated DNA sequencing (ddRAD), transcriptomes, nuclear ribosomal internal transcribed spacer (nrITS), and the small single-copy region of the chloroplast genome, in combination with morphological evidence to help resolve taxonomic ambiguity of those rare and threatened species. Conflicting relationships were derived from nuclear and chloroplast sequences. The strong hybridization/introgression signal detected suggests reticulate evolution mainly caused this discordance pattern. The nuclear-ddRAD and RNA-seq phylogenies fit better to the yellow camellias' morphology, providing a clear resolution for inferring their relationships in China. Based on present phylogenetic analyses and morphological characters, we propose these taxonomic suggestions: (i) Camellia petelotii and Camellia nitidissima are distinct species; (ii) Camellia ptilosperma, Camellia longruiensis, Camellia longgangensis, and C. longgangensis var. grandis are conspecific with Camellia flavida; (iii) Camellia multipetala and C. longgangensis var. patens are synonyms of Camellia quinqueloculosa, and C. quinqueloculosa should be recognized as an independent species; (iv) Camellia wumingensis should be formally recognized as an independent species; (v) Camellia longzhouensis is a synonym of Camellia chrysanthoides; (vi) Camellia xiashiensis and Camellia parvipetala should be treated as synonyms of Camellia micrantha; (vii) Camellia achrysantha is a good species; (viii) Camellia tunghinensis is an independent species; (ix) species status of Camellia huana is well-supported; and (x) Camellia pingguoensis var. terminals should be correctly identified to species level as Camellia terminalis. These results provide the basis for the recognition 20 yellow Camellia species in China.

Key words: chloroplast DNA sequence, ddRAD, hybridization, nrITS, taxonomy, transcriptome, yellow camellias