Impatiens shimianensis sp nov (Balsaminaceae): A New Species from Sichuan, China, based on Morphological and Molecular Evidence

A new species, Impatiens shimianensis (Balsaminaceae), is described and illustrated. Impatiens shimianensis is morphologically most similar to I. delavayi in having ovate or ovate-orbicular leaves, crenate leaf margins, and bilobed spurs. The two species differ in that I. shimianensis has an orbicular upper petal of lateral united petals and shortly clawed lateral united petals while I. delavayi has a subtetragonous upper petal of lateral united petals and conspicuously clawed lateral united petals. The upper portion of the lower sepal of I. shimianensis is yellow and the lower portion of the lower sepal has brown stripes, whereas the whole lower sepal of I. delavayi is dark purple or pink. In addition, the petals of I. shimianensis are yellow or whitish yellow, whereas those of I. delavayi are dirty yellow or pink. Phylogenetic analyses based on DNA sequences from the nuclear internal transcribed spacer (ITS) and the chloroplast atpB-rbcL intergenic spacer showed that I. shimianensis fell within a well-supported clade composed of I. barbata, I. corchorifolia, I. delavayi, and I. poculifer. In addition to these species, a few other morphologically similar species that were not sampled for the molecular phylogenetic component of this study were compared with the species newly discovered. Impatiens shimianensis can easily be distinguished morphologically from all these species by its yellowish white flowers, dark red spur tip, and purple abaxial leaf surface.