A new combination and synonym in Bupleurum (Apiaceae, Apioideae), based on morphological, molecular and cytological evidence.

Abstract

Specimen examinations and field observations revealed that Bupleurumsmithiivar.parvifolium was distinctly different from B.smithiivar.smithii in umbel, leaf, and fruit morphology, but was very similar to B.commelynoideumvar.flaviflorum. Based on these morphological evidences, the present study re-examined the taxonomic status of these taxa through morphological, cytological, and phylogenetic analyses. The results showed distinguishable features in the width of middle leaves and bracteoles of B.smithiivar.parvifolium compared to B.smithiivar.smithii. Morphological variation between B.smithiivar.parvifolium and B.commelynoideumvar.flaviflorum was continuous and overlapping. Notably, the chromosome number of B.smithiivar.parvifolium was 2n = 14 (x = 7), consistent with B.commelynoideumvar.flaviflorum, whereas B.smithiivar.smithii was 2n = 64 (x = 8). Additionally, phylogenetic analyses revealed B.commelynoideumvar.flaviflorum nested within B.smithiivar.parvifolium, and that both were distant from the B.smithiivar.smithii and B.commelynoideumvar.commelynoideum. Based on the evidence above, the differences between B.smithiivar.parvifolium and B.smithiivar.smithii extend beyond the level of intraspecific variation, and B.commelynoideumvar.flaviflorum is considered to be identical with B.smithiivar.parvifolium. Hence. A new combination and status, B.parvifolium (Shan & Y.Li) Q.R.Liu & L.H.Wang, comb. et stat. nov., is proposed. Furthermore, B.commelynoideumvar.flaviflorum should be treated as a synonym of B.parvifolium.