SummaryThe genetic diversity of all available culture strains of the Tribonemataceae (Stramenopiles, Xanthophyceae) from Antarctica was assessed using the chloroplast-encoded psbA/rbcL spacer region sequences, a highly variable molecular marker, to test for endemism when compared with their closest temperate relatives. There was no species endemic for Antarctica, and no phylogenetic clade corresponded to a limited geographical region. However, species of the Tribonemataceae may have Antarctic populations that are distinct from those of other regions because the Antarctic strain spacer sequences were not identical to sequences from temperate regions. Spacer sequences from five new Antarctic isolates were identical to one or more previously available Antarctic strains, indicating that the Tribonemataceae diversity in Antarctic may be rather limited. Direct comparisons of the spacer sequences and phylogenetic analyses of the more conserved rbcL gene revealed that current morphospecies were inadequate to describe the actual biodiversity of the group. For example, the genus Xanthonema, as currently circumscribed, was paraphyletic. Fortunately, the presence of distinctive sequence regions within the psbA/rbcL spacer, together with differences in the rbcL phylogeny, provided significant autoapomorphic criteria to re-define the Tribonemataceae species.
The present study is focused on several species from the genus Astragalus L. with the aim to clarify the taxonomic status of Ukrainian local endemic species Astragalus borysthenicus Klokov, which is sometimes considered a synonym to A. onobrychis L. In this study, the morphological features, current taxonomy, taxonomical history, and phylogenetic analysis based on rDNA Bayesian inference, as well as comparative analysis of ITS1 and ITS2 secondary structures, were investigated. It was found that A. borysthenicus is distant from A. onobrychis according to phylogenetic analysis. Moreover, A. borysthenicus has differences from the investigated taxa in its secondary structures of ITS1 and ITS2 transcripts. These data suggest that A. borysthenicus should be treated as a separate species rather than a synonym to A. onobrychis.
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