AUTHOR=Wang Ting , Chen Ling-Ling , Shu Hui-Juan , You Fang , Liang Xiao-Li , Li Jun , Ren Jing , Wanga Vincent Okelo , Mutie Fredrick Munyao , Cai Xiu-Zhen , Liu Ke-Ming , Hu Guang-Wan 

TITLE=Fortunella venosa (Champ. ex Benth.) C. C. Huang and F. hindsii (Champ. ex Benth.) Swingle as Independent Species: Evidence From Morphology and Molecular Systematics and Taxonomic Revision of Fortunella (Rutaceae)

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.867659

DOI=10.3389/fpls.2022.867659

ISSN=1664-462X

ABSTRACT=<p>Recently, the systematic status of <italic>Fortunella</italic> Swingle and its taxonomy has attracted much attention. Flora of China incorporates <italic>Fortunella</italic> into <italic>Citrus</italic> Linn. and treats all species of the traditional <italic>Fortunella</italic> as one species, namely <italic>Citrus japonica</italic> (Thunb.) Swingle. Furthermore, <italic>F. venosa</italic> (Champ. ex Benth.) C. C. Huang and <italic>F. hindsii</italic> (Champ. ex Benth.) Swingle are currently considered as synonyms of <italic>C. japonica</italic>. In this paper, morphological, palynological, and phylogenetic analyses were used to systematically explore the taxonomic status of traditional <italic>Fortunella</italic>. The key morphological features that differed among the <italic>Fortunella</italic> species were the leaf and the petiole hence could be key in its taxonomic classification of the species. Additionally, pollen morphological analysis based on the pollen size, germination grooves, polar, and equatorial axes also supported the separation of the species. The results of the phylogenetic analysis showed that each of the three species clustered separately, hence strongly supporting the conclusion of independent species. In addition, the phylogenetic analysis showed that the two genera clustered closely together hence our results support the incorporation of <italic>Fortunella</italic> into <italic>Citrus</italic>. Based on the above, this article has revised the classification of the traditional <italic>Fortunella</italic> and determined that this genus has three species, namely; <italic>F. venosa</italic>, <italic>F. hindsii</italic>, and <italic>F. japonica</italic>. <italic>F. venosa</italic> and <italic>F. hindsii</italic> are placed in the <italic>Citrus</italic> as separate species, and their species names still use the previous specific epithet. The revised scientific names of the new combinations of <italic>F. venosa</italic> and <italic>F. hindsii</italic> are as follows: <italic>Citrus venosa</italic> (Champ. ex Benth.) K. M. Liu, X. Z. Cai, and G. W. Hu, <italic>comb. nov</italic>. and <italic>Citrus hindsii</italic> (Champ. ex Benth.) K. M. Liu, G. W. Hu, and X. Z. Cai, <italic>comb. nov</italic>. <italic>F. venosa</italic> is the original species of <italic>Fortunella</italic>, <italic>F. venosa</italic> and <italic>F. hindsii</italic> are both listed as the second-class key protected wild plants in China. Therefore, the establishment of the taxonomic status of <italic>F. venosa</italic> and <italic>F. hindsii</italic> not only deepens our understanding, importance, and the complexity of the systematic classification of <italic>Fortunella</italic>, but is also significant for global biodiversity conservation, genetic resources for breeding purposes, and population genetics.</p>