No abstract

Various names have been used for Assam tea and they are typified here. The currently widely used name, Camellia sinensis var. assamica, is a combination based on Thea viridis var. assamica, not “T. assamica” because the latter was never validly published. Two earlier published names, C. theifera and T. cochinchinensis, and two later ones, C. tenuistipa and T. yersinii, may represent the same taxon and are treated as synonyms of T. viridis var. assamica because the latter has priority at the rank of variety and therefore is the correct name for Assam tea.

Camellia contains tea, oil camellia, and camellias which benefit people globally. Its infrageneric classification is, however, controversial and unstable, and former phylogenetic analyses failed to yield robust and consistent trees. Here, we aimed to reconstruct a robust phylogenetic tree, date all clades and discuss the evolutionary history of Camellia. Emphasizing the taxonomically comprehensive sampling rather than more DNA data, orthologous nuclear RPB2 introns 11-15 and 23, and waxy were sequenced for 99 taxa of Camellia to reconstruct its phylogenetic history. Ten clades are identified in Camellia: Camellia II, Camelliopsis, Corallina, Furfuracea, Heterogenea, Paracamellia, Piquetia, Stereocarpus, Thea and Yellow camellias II. Camellia grijsii and C. shensiensis are not closely related with other oil camellias that form the clade Paracamellia. Sections Camelliopsis and Theopsis together form the clade Camelliopsis, while clade Furfuracea consists of sect. Furfuracea and C. hongkongensis. Camellia connata is separated from C. lanceolata but nested in the clade Heterogenea, and C. longissima is nested in the clade Thea, suggesting a new germplasm for tea breeding. Molecular dating using four fossil calibration points suggests that the crown age of Camellia is 39.5 Ma with clade Corallina probably the earliest infrageneric clade to diversify and the most widespread clade, Paracamellia, the latest. Our findings provide new insights into the phylogenetic relationships, systematics and evolutionary history of Camellia.

Nomenclatural types for 18 names actually belonging to the genus Camellia are designated here. The following names are lectotypified: Camellia caudata, C. indochinensis, Dankia langbianensis, Thea bachmaensis, T. brachystemon, T. confusa, T. connata, T. corallina, T. fleuryi, T. gaudichaudii, T. gilbertii, T. krempfii, T. laotica, T. nematodea, T. nervosa, T. pleurocarpa, T. taliensis and T. tonkinensis.

Camellia cucphuongensis, C. cylindracea and C. vidalii are treated as heterotypic synonyms of C. flava, C. amplexicaulis and C. langbianensis, respectively.