Synotis xinningensis (Asteraceae), a new species from Hunan, China.

Background: Synotis is one of the several genera within Senecioneae (Asteraceae) with more than 40 species that are mainly distributed in China or in the Sino-Himalayan region. During a botanical expedition in central and southwestern China in 2011, we found an unusual population of Synotis in southwestern Hunan Province. To determine the taxonomic identity of the population, we carried out gross-morphological, floral micromorphological, and cytological observations.

Results: Our gross-morphological observations have shown that the population is most similar to Synotis changiana Y. L. Chen, but readily distinguishable in the discoid capitula (vs. radiate), and in the bracts of calyculus 9-10 (vs. 6-8), 6-7 mm long (vs. 3-4 mm). The floral micromorphological observations on the population and S. changiana agree with previous reports for other species of Synotis. The chromosomes of the population are counted to be 2n = 40 + 0-1B. Its karyotype is formulated as 2n = 22m + 14sm + 4st.

Conclusions: The population is determined to represent a new species, i.e. Synotis xinningensis M. Tang & Q. E. Yang, which is described herein. The new species belongs to Synotis ser. Synotis.