Systematic Placement of the Enigmatic Southeast Asian Genus Paralamium and an Updated Phylogeny of Tribe Pogostemoneae (Lamiaceae Subfamily Lamioideae)

Abstract

Paralamium (Lamiaceae) is a monotypic genus within the subfamily Lamioideae and has a sporadic distribution in subtropical mountains of southeast Asia. Although recent studies have greatly improved our understanding of generic relationships within Lamioideae, the second most species-rich subfamily of Lamiaceae, the systematic position of Paralamium within the subfamily remains unclear. In this study, we investigate the phylogenetic placement of the genus using three datasets: (1) a 69,276 bp plastome alignment of Lamiaceae; (2) a five chloroplast DNA region dataset of tribe Pogostemoneae, and (3) a nuclear ribosomal internal transcribed spacer region dataset of Pogostemoneae. These analyses demonstrate that Paralamium is a member of Pogostemoneae and sister to the monotypic genus Craniotome. In addition, generic-level phylogenetic relationships within Pogostemoneae are also discussed, and a dichotomous key for genera within Pogostemoneae is provided.

The complete chloroplast genome of Callicarpa rubella Lindl. (Lamiaceae) from Guangxi, China: genome structure and phylogenetic analysis

“… 2021 ; Zhao, Wu, et al. 2021 ). Due to the rapid development of molecular phylogenic studies during the past two decades, the traditionally systematic positions of some genera have dramatically changed.…”

Home at last: Molecular phylogenetic analyses support subsuming Metastachydium within Phlomoides (Lamiaceae)

“…Spach (Chen & al., 2022b). In general, the incongruities between plastid and nuclear DNA markers within Lamiaceae have been explained by incomplete lineage sorting (ILS) and/or hybridization (Albaladejo & al., 2005; Drew & Sytsma, 2013; Drew & al., 2014; Deng & al., 2015; Walker & al., 2015; Hu & al., 2018; F. Zhao & al., 2021b; Chen & al., 2022b).…”

“…from subfamily Cymarioideae, the sister group of Lamioideae (Li & al., 2016; F. Zhao & al., 2021a, 2021b), was also included as an ingroup. Six species from subfamily Scutellarioideae were selected as the outgroup based on the results from previous phylogenetic analyses (Li & al., 2016; F. Zhao & al., 2021a, 2021b). We reconstructed the backbone phylogeny of Lamioideae using 80 plastid‐encoded protein genes (dataset CP80), with plastomes from 2 individuals of M. sagittatum , 12 species of Phlomoides , 1 species of Phlomis L., 2 species of Paraphlomis (Prain) Prain, and 1 species of Betonica newly sequenced for this study, and the remaining 50 accessions downloaded from GenBank (suppl.…”

“…from subfamily Cymarioideae, the sister group of Lamioideae F. Zhao & al., 2021aF. Zhao & al., , 2021b, was also included as an ingroup.…”

“…Cantino & Sanders (1986) placed Metastachydium in subfamily Lamioideae based on pollen morphology (i.e., the presence of tricolpate and 2‐celled pollen), and this treatment was adopted by subsequent taxonomists (Abu‐Asab & Cantino, 1994; Li & Hedge, 1994; Harley & al., 2004; Olmstead, 2016). Although major progress has been made towards elucidating phylogenetic relationships within Lamioideae, the placement of Metastachydium has remained elusive and the genus has not been assigned to any of the tribes updated by recent phylogenetic studies (Scheen & al., 2010; Bendiksby & al., 2011; F. Zhao & al., 2021b). Some morphological characters (i.e., bracts subulate and calyx teeth with apical spines) of Metastachydium point to a kinship with Phlomoides Moench, but this relationship has not been explored using molecular data.…”