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

Specimen examinations and field observations revealed that Bupleurum smithii var. parvifolium was distinctly different from B. smithii var. smithii in umbel, leaf, and fruit morphology, but was very similar to B. commelynoideum var. 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. smithii var. parvifolium compared to B. smithii var. smithii. Morphological variation between B. smithii var. parvifolium and B. commelynoideum var. flaviflorum was continuous and overlapping. Notably, the chromosome number of B. smithii var. parvifolium was 2n = 14 (x = 7), consistent with B. commelynoideum var. flaviflorum, whereas B. smithii var. smithii was 2n = 64 (x = 8). Additionally, phylogenetic analyses revealed B. commelynoideum var. flaviflorum nested within B. smithii var. parvifolium, and that both were distant from the B. smithii var. smithii and B. commelynoideum var. commelynoideum. Based on the evidence above, the differences between B. smithii var. parvifolium and B. smithii var. smithii extend beyond the level of intraspecific variation, and B. commelynoideum var. flaviflorum is considered to be identical with B. smithii var. 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. commelynoideum var. flaviflorum should be treated as a synonym of B. parvifolium.