A reevaluation of the Andean Genus Petroravenia (Brassicaceae: Thelypodieae) based on morphological and molecular data

Abstract

Petroravenia was until recently considered as a genus of three species (P. eseptata, P. friesii, and P. werdermannii) distributed along the Central Andes of Argentina, Bolivia, Chile, and Peru. This genus was included in the tribe Thelypodieae and was morphologically characterized by being tiny rhizomatous perennial herbs with rosulate leaves, dendritic trichomes, capsular silicles, and incumbent cotyledons. However, the phylogeny of Petroravenia, and its tribal placement, was never analyzed using molecular data. The lack of such studies, as well as the paucity of herbarium collections, suggesting that Petroravenia species are vulnerable and/or endangered, prompted us to address the molecular phylogeny of this genus. For this purpose, we generated comprehensive molecular phylogenies using nuclear (ITS) and plastid (trnL‐F and trnH‐psbA) data, and conducted morphological comparisons between these species and their closest related taxa. Results from the phylogenetic analyses showed that Petroravenia represents a polyphyletic group, with P. eseptata included in tribe Halimolobeae, and P. friesii and P. werdermannii placed within tribe Eudemeae and related to the genus Alshehbazia. Based on the results obtained from morphological and molecular data, we decided herein to retain the original circumscription of Petroravenia as monospecific within the tribe Halimolobeae and to transfer P. friesii and P. werdermannii to the genus Alshehbazia within the tribe Eudemeae. Systematic implications of these results are also discussed.