Phylogenetic position of Dorema within Ferula (Apiaceae)

Abstract

Dorema (Apiaceae) includes 12 species distributed in the Irano-Turanian region. The genus differs from other genera of subfamily Apioideae in having paniculate inflorescences with simple umbels. Recently, molecular phylogenetic analyses placed six species of Dorema, including the generitype, in Ferula, thus subsuming the former into the synonymy of the latter. The remaining six congeners have not been yet included in molecular analyses. Here, we fill this gap by determining the phylogenetic position of these species. Because of a low resolution in some parts of the Ferula tree in earlier studies, alongside standard set of markers—nuclear nrDNA ITS and plastid rps16 and rpoC1 introns and the rpoB-trnC intergenic spacer—we additionally assessed the utility of nrDNA ETS sequences in resolving infrageneric relationships in the genus. We included 43 ingroup species representing major infrageneric divisions recognised in the most recent taxonomic revision. Although we were not successful in obtaining all markers for all newly studied species, they were placed with high support in one clade within section Peucedanoides together with formerly studied congeners in all maximum likelihood and Bayesian analyses of nuclear, plastid, and combined data sets. The addition of the ETS marker to the combined phylogenetic analyses confirmed the most recent classification of Ferula with increased branch support in some parts of the tree. However, many branches still remained unresolved. In particular, the monophyly of former Dorema within section Peucedanoides as suggested by morphology has not been definitely confirmed. A new combination and two nomina nova are proposed.