Plastid phylogenomics with broad taxon sampling provides insights into the generic delimitation of Paraphlomideae (Lamiaceae)

Abstract

Paraphlomideae (Lamioideae, Lamiaceae) is a recently established tribe endemic to East and Southeast Asia. It comprises three herbaceous genera: Paraphlomis, Matsumurella, and Ajugoides. Phylogenetic relationships among these genera have not yet been satisfactorily resolved and the monophyly of Paraphlomis was challenged in previous molecular phylogenetic studies. In this study, we performed maximum likelihood and Bayesian inference analyses on complete plastomes and nuclear ribosomal internal and external transcribed spacer sequences to further resolve the generic relationships within Paraphlomideae. All phylogenetic analyses support the monophyly of Paraphlomideae. Contrary to traditional classifications, both Ajugoides and Matsumurella were deeply nested within Paraphlomis, indicating the need to expand Paraphlomis to include Ajugoides and Matsumurella. Hence, six new combinations and one replacement name are proposed. Morphologically, species of the newly defined Paraphlomis share a rhizomatous or stoloniferous habit, plants with simple hairs, nutlets with a truncate apex, and actinomorphic calyces. In addition, widespread incongruence between nuclear and plastid trees may have been caused by hybridization and incomplete lineage sorting after rapid diversification in the re‐circumscribed Paraphlomis.