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The Chapada Diamantina (CD) clade (Asteraceae, Eupatorieae) comprises 26 species distributed among six genera ( Agrianthus , Arrojadocharis , Bishopiella , Lasiolaena, Semiria , and Stylotrichium ) endemic to the high elevations of the Espinhaço Range in Brazil. We aimed to clarify phylogenetic relationships within the CD clade, which shows low genetic differentiation, high morphological variation, and unclear species delimitation. The DNA sequences of four plastid ( psb A- trn H, trn C- pet N, trn Y- rpo B, and trn L- trn F with trn L intron) and three nuclear markers (ITS and low-copy regions gsh1 and shmt ) allowed the construction of a dataset with 96% of the species described for the clade. Our results confirm that the CD clade is monophyletic and originated during the Pliocene (5.1 Mya), with subsequent diversification in the Pleistocene (2.5 Mya). Phylogenetic analysis also confirmed Bishopiella and Semiria as monotypic genera, a broader circumscription of Agrianthus including Arrojadocharis and two species of Lasiolaena , and that Lasiolaena and Stylotrichium are sister groups. In addition, four potential hybrids were detected, possibly providing evidence that reticulate evolution has occurred in the CD clade. Further studies with endemic and sympatric species with recent radiation could benefit from approaches combining phylogenetic trees and non-tree-like results, as well as nuclear markers, to propose improved explanations for the underlying evolutionary mechanisms generating diversity.
Amorim et al. (Fri,) studied this question.