Pinellia discolor: a new cryptic species distinguished from P. cordata in mainland China

Pinellia cordata (Araceae) is a perennial herb species distributed in China and Japan. Several studies have shown that there are two types of this species, and chromosome counts have shown irregular variation among populations. In this study, we investigated the morphological characteristics, established the chromosome number in root tips, reconstructed phylogenetic relationship based on whole chloroplast genomes, and elucidated biogeographic patterns based on data collected from the Chinese Virtual Herbarium (CVH) and the Plant Photo Bank of China (PPBC) for the two types of P. cordata, including type I (greenish leaf blade) and type II (colored leaf blade). We found stable significant differences in morphometric characteristics (color of the leaf blade abaxially, petiole, spathe and appendix) and the number of chromosomes. The results of the phylogenetic analysis showed that types I and II were located to different places in the evolutionary tree compared to the group. The distribution regions of these types of P. cordata were also slightly different in mainland China. These findings suggested that P. cordata should be divided into P. cordata (type I) and Pinellia discolor (type II, a cryptic species) and the latter is here described as a new species.