Molecular investigation of the phylogenetic placement of Kartalinia and a revision of Bituminaria (Fabaceae: Psoraleeae)

Abstract

The genus Kartalinia was described to accommodate a single, obscure species, Psoralea acaulis , based on its unique morphology and karyology. No concerted molecular phylogenetic studies were available for this species at the time, and therefore its phylogenetic position was uncertain. We aim to establish its phylogenetic relationships, using a combination of nuclear and plastid markers, testing hypotheses on its previous placement as a subgenus in Bituminaria . Evolutionary patterns of characters used in taxonomic diagnoses were evaluated to identify synapomorphies for clades. Silica‐dried leaf material representing the morphological and geographical range of Bituminaria sensu lato were used for genomic DNA extractions following the standard CTAB protocol. Sanger sequencing was performed for the nuclear internal transcribed spacer (ITS) and plastid matK , trnS‐trnG , and trnL‐trnF regions. Additional sequences representing all Psoraleeae genera were downloaded from GenBank and incorporated into our sequence alignments. Maximum‐likelihood phylogenies were inferred using IQ‐TREE, separately for nuclear and plastid gene regions, and concatenation was not performed due to phylogenetic incongruence. Diagnostic morphological characters were mapped on the phylogeny, using parsimony, to unravel their evolutionary patterns. Both phylogenies resolved Kartalinia as sister to the rest of the tribe Psoraleeae, although the evolutionary history of the tribe requires further investigation as previous studies on biogeography and molecular dating excluded sequence data for Kartalinia . This study thus confirms that Kartalinia is distinct from Bituminaria , and other genera in the tribe, and supports the morphological and karyological data used to circumscribe this genus. A taxonomic revision of Bituminaria is also presented, with 17 species recognised and illustrated, including the description of four new species and three new combinations.