Primulina cardaminifolia (Gesneriaceae), a rare new species from limestone areas in Guangxi, China

Abstract

Abstract Background Primulina cardaminifolia Yan Liu & W.B. Xu (Gesneriaceae), a distinct new species with imparipinnate leaves, is described and illustrated from a limestone valley in Guangxi Zhuangzu Autonomous Region, China. To assure its generic placement and phylogenetic affinity, phylogenetic analyses were performed using DNA sequences of nuclear ITS and chloroplast trnL-F intron spacer region. Additionally, somatic chromosome number was counted and pollen stainability was tested. Results Phylogenetic analyses support its placement in Primulina; however, two phylogenetically distinct ITS sequence types were detected, suggesting a probable hybrid origin. Its pollen stainability is 100% and its chromosome number, 2n = 36, is congruent with all known counts of diploid species of the genus. Conclusion All available data support the recognition of the new species Primulina cardaminifolia and suggest that it could have derived from homoploid hybrid speciation. Color plates, line drawings and a distribution map are provided to aid in identification.