Molecular phylogeny of Astragalus section Anthylloidei (Fabaceae) inferred from nrDNA ITS and plastid rpl32-trnL(UAG) sequence data

Abstract

The phylogeny of Astragalus L. section Anthylloidei DC. and its interrelationship with allies were examined. The study was conducted using nrDNA ITS and plastid rpl32-trnL (UAG) sequences. Astragalus sect. Anthylloidei is nonmonophyletic, and its members are scattered across the tree in 4 well-supported clades and intermixed with members of other spiny sections. All the multispecific informal groups of the section, with the exception of A. murinus Boiss. group, are not monophyletic. Morphological character evolution was mapped on the molecular tree. Our results suggest that morphology cannot elucidate infrageneric relationships in spiny Astragalus accurately; analyzed characters have evolved several times in sect. Anthylloidei and, thus, show high levels of homoplasy. Distribution of members of the section matches, more or less, certain geographic patterns, ranging from the Zagros mountains, Northwest Iran and Eastern Turkey, Central Iran to Northeast Iran, and Turkmenistan and Afghanistan. A new taxonomic system for this group of species is needed. The present study suggests that sect. Halicacabus Bunge, which has been merged with sect. Anthylloidei, should be resurrected since 8 species, including A. halicacabus Lam; A. wagneri Bartl. ex Bunge; A. distans Fisch.; A. raswendicus Hausskn. & Bornm.; A. veiskaramii Zarre, Podlech & T.Sabaii; A. submitis Boiss. & Hohen.; and A. chardinii Boiss. (sect. Anthylloidei) as well as A. semnanensis Bornm. & Rech. f. (sect. Semnanenses Podlech & Zarre), form a distinct clade. Sect. Eriostoma Bornm. is a distinct lineage from sect. Anthylloidei.