Systematic position of Oreosolen （tribe Scrophularieae, Scrophulariaceae） based on nuclear and plastid sequences

The genera Oreosolen and Scrophularia （Scrophulariaceae） were assumed to be closely related due to the considerable similarity in morphology. Their sister relationship was even suggested in a few molecular phylogenetic studies. However, this proposed relationship is not so convincing due to insufficient sampling of Scrophularia. In this study, the systematic position of Oreosolen was reassessed based on more sampling of both taxa and molecular traits. A total of lo4 accessions representing 89 taxa were sampled, including 87 （85 taxa） of Scrophularia, 14 （one taxon） of Oreosolen, and three outgroups. The phylogenetic relationships between Oreosolen and Scrophularia were inferred based on one nuclear （internal transcribed spacer） and three plastid （trnL-F, psbA-trnH, and trnQ-rps16） DNA regions using maximum parsimony, maximum likelihood, and Bayesian inference methods. The results revealed that Oreosolen was nested within Scrophularia and thus its generic status was not supported. Its type species, Oreosolen wattii Hook. f., was then transferred to Scrophularia and a new combination （Scrophularia wattii （Hook. f.） P. Li） was proposed. Oreosolen and its sympatric ally, Phlomoides rotata （Benth. ex Hook. f.） Mathiesen （= Lamiophlomis rotata （Benth. ex Hook. f.） Kudo, Lamiaceae）, might undergo convergent evolution of acaulescence and rosulate leaves driven by the harsh alpine environment.