|其他摘要||In the classical taxonomy of the Genus Camellia, the phylogenetic relationship of Sect. Archecamellia Sealy and Sect. Chrysantha H. T. Chang is confused and in dispute. One opinion is that the two sections with different characteristics, and are treated as two natural groups in the classification of Camellia. Another is that two sections are closely related with very similar characteristics, and Sect. Chrysantha should be combined with Sect. Archecamllia. The divergence of opinion is mainly caused by the disparate understanding on the morphological traits in Camellia species. With no available criterion, the problem has not resolved yet.
This paper introduced the means of molecular systematics to resolve the above problem, and the phylogenetic relationships among Sect. Archecamellia and Sect. Chrysantha species is reconstructed. Special attention has been paid to the circumscription of Sect. Archecamellia and Sect. Chrysantha, and the relationship of the two sections. In addition, interspecies relationship and geographical distribution with the section(s) were discussed. Major results were summarized as follows:
Inferred from the combined analyses based on four chloroplast DNA regions (trnL-F、trnH-psbA、trnL-rpl32、rpl16) and one nuclear gene (GBSSI) of 36 taxa of Sect. Archecamellia and Sect. Chrysantha and related sections, molecular systematics of the two sections was elucidated. The results implied that the Sect. Archecamellia sensu Sealy and the Sect. Chrysantha sensu H. T. Chang were not monophyletic. Camellia petelotii of Sect. Archecamellia, and Sect. Chrysantha, formed a well-supported monophyletic clade, while a species of Sect. Archecamellia, C. amplexicaulis, fell into another clade. Based on the result of the sampled species (including the type species of the latter section), we suggested that Sect. Chrysantha should be combined with Sect. Archecamllia, and C. amplexicaulis should be excluded from Sect. Archecamllia. The newly circumscribed Sect. Archecamllia included C. petelotii and all taxa previously treated in Sect. Chrysantha with yellow corolla being their synapomorphic character. Because of the lack of some other species of Sect. Archecamllia, such as C. krempfii, and C. flava, this conclusion should be confirmed by studies with more sampling and evidence.
The newly circumscribed Sect. Archecamllia includes four clades. The species distributed in north Vietnam, represented by C. petelotii, clustered into a clade, which contains C. petelotii, C. crassiphylla, C. hirsuta, C. murauchii, C. tamdaoensis, C. hakodae, C. thanxaensis and C. phanii. The species from China formed the other three clades. They mainly confined to Guangxi, and the Shi-wan Da Shan (Mountain) is an important borderline, which separates the distributional area into two regions, the Fangcheng region which located in the southeast of the Mountain and the large region in the northwest of the Mountain, which contains several counties, including Longzhou, Ningming, Fusui, Pingguo, etc. Four species, C. euphlebia, C. tunghinensis, C. nitidissima, and C. nitidissima var. phaeopubisperma, from the Fangcheng region formed one clade. The majority of species distributed in the northwest of the Mountain formed the next one, and C. longzhouensis and C. longgangensis formed the third one. It is noteworthy the interspecies relationships within the section are corresponded to their geographical distributions.|