Molecular Phylogeny of Chinese Conyza,Microglossa and Thespis (Asteraceae：Astereae) Based on Two Nuclear Ribosomal DNA Regions

Chinese subtribe Conyzinae (Asteraceae：Astereae) consists of three small genera,Conyza,Microglossa and Thespis. To date,however,the molecular phylogenetic relationships among African Conyza,and Chinese Conyza,Thespis and Microglossa have not been investigated. The internal and external transcribed spacers of nuclear ribosomal DNA were used to reconstruct the phylogeny of Chinese Conyzinae through maximum parsimony and Bayesian analyses. Results showed that four Chinese Conyza species and Thespis divaricata belonged to a clade with most sampled African Conyza,whereas two Conyza stricta varieties and Microglossa pyrifolia were embedded deeply within the subtribe Grangeinae clade. Microglossa pyrifolia was closely related to Psiadia pascalii. Based on phylogeny,we considered that (1) C. stricta and C. incisa should be treated as a separate genus that belongs to subtribe Grangeiane;(2) four Chinese Conyza,Thespis and most sampled African Conyza belong to the genus Eschenbachia. Eschenbachia should belong to a new separate subtribe,while Thespis should be treated as a section of Eschenbachia. Eschenbachia may have arrived at southern China by several long-distance dispersals from Africa;(3) it is reasonable to maintain the generic status of Welwitschiella and Microglossa and treat Psiadia pascalii,C. scabrida and C. pyrrhopappa as members of Microglossa.