Three New Species of Petrocodon (Gesneriaceae), Endemic to the Limestone Areas of Southwest China, and Preliminary Insights into the Diversification Patterns of the Genus

摘要

Three new species of Gesneriaceae, Petrocodon ainsliifolius, Petrocodon litizophilus, Petrocodon viridescens, from limestone areas of Yunnan, China are described and illustrated. Their independent species status is demonstrated in phylogenetic analyses using nuclear ribosomal internal transcribed spacer and chloroplast trnLF intron-spacer sequences. The phylogenetic and taxonomic relationships with their congeners are discussed from a morphological point of view. Morphological convergences, particularly of the flower, appear to characterize this calciphilous genus. Preliminary results are based on the material included, phylogenetic relationships inferred, and geographic distributions. The limestone area in Southeast Yunnan and West Guangxi appears as the center of origin and diversification of Petrocodon, with separate range expansions to eastern karst regions.