Phylogenetic relationships, biogeography and taxonomic delimitation of Astragalus sect. Acanthophace (Fabaceae) using cpDNA and nrDNA ITS sequences analyses

Abstract

Phylogenetic relationships within Astragalus sect. Acanthophace and several spiny Astragalus species were studied using nuclear ribosomal DNA internal transcribed spacer (nrDNA ITS) and two plastid intergenic spacers (rpl32-trnL^(UAG) and trnS^(GCU)–trnG^(UCC)). The strongly congruent expression using maximum likelihood and Bayesian inference methods was the non-monophyly of sect. Acanthophace at the current status suggesting the exclusion of A. ovigerus and A. lamprocarpus as a single clade. This study also shed light on taxonomic controversies on the synonymy of A. lamprocarpus under A. ovigerus and indicated the non-monophyly of A. lycioides complex, since one accession of A. lycioides (sect. Acanthophace) united with members of A. sect. Aegacantha (resurrected as A. pseudoangustifolius). Another interesting finding was the unexpected placement of A. montis-parrowii (sect. Aegacantha) within the bulk of spiny Astragalus (Astracantha clade). The reconstructed plastid and nrDNA ITS trees showed considerable conflict in the position of several species. Biogeographical analyses indicated that sect. Acanthophace was most probably originated in western Iran.

Keywords:

• Acanthophace
• Aegacantha
• Astragalus
• biogeography
• incongruence
• nrDNA ITS
• phylogeny

Acknowledgment

Authors would like to thank the staff of herbaria MSB, W and TARI to allow studying herbarium specimens and providing leaf materials.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was carried out with the financial support of the research council of the Tarbiat Modares University.