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This study describes the new species Astragalus oksutdagensis (A. sect. Eustales) from Kayseri, Turkey. The species is compared morphologically to the two similar species A. flavescens and A. vestitus, considering also pollen micromorphology. The geographical distribution of A. oksutdagensis, A. vestitus and A. flavescens is mapped. The phylogenetic relationships between the new species and other closely related species in the genus are inferred based on DNA data from the internal transcribed spacer regions (ITS) and it is shown that A. sect. Eustales is monophyletic but closely related to A. sect. Tragacantha. The new species is assessed as critically endangered (CR) following the IUCN Red List Categories and Criteria.

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The general purpose of the molecular systematic studies is to illuminate the ITS2 structure of the target populations, to determine its phylogenetic boundaries, and to clarify intra-species and inter-species relationships. Particularly, the internal transcribed spacer 2 (ITS2) region of nuclear ribosomal DNA is used in molecular systematics because of availability of conserved regions with its highly repeated in number in plant genomes. Addition to the primary sequences of ITS2, also secondary structure form of the region became a valuable feature in species divergence and became to use like a morphological character. In the current study to indicate the secondary structure form of the ITS2 region as a useful tool in systematics, different taxa from 22 genera were used. The DNA samples were collected in the field studies in 2021 and sequences were aligned using ClustalW and Kimura-2 parameter to calculate the genetic distances. Phylogenetic tree was also constructed with Maximum Likelihood method with the best suitable model at MEGA X software. The secondary structure predictions of species and ΔG (Gibbs) free energy calculations, the tools of both the ITS2 database and mFOLD web server were used. The results indicated that ITS2 secondary structure estimations represented the genetic differences visibly with its helices and motifs like a morphological character. Consequently, even if primary structure of the ITS2 region revealed as valuable marker in molecular systematic studies, also, all tested secondary structure forms of the region will be used as an ideal marker for taxonomic and phylogenetic reconstructions at all taxonomic levels.

Background ITS2 sequences can be used in systematic studies and proved to give reliable results in the distinguishing of Trichogramma species (Hymenoptera: Trichogrammatidae). Correct identification of natural enemies forms the basis of a biological control program. The present study aimed to compare sequences of rDNA-ITS2 of Trichogramma samples with those deposited in GenBank by using ITS2, as a barcode for reliable species identification and assessment of genetic diversity. Results Molecular identification methods were used to differentiate 2 Trichogramma species collected from Adana province of Turkey; Trichogramma brassicae (Bezdenko) and Trichogramma turkestanica Meyer (Hymenoptera: Trichogrammatidae). ITS2 sequences of samples ranged in size from 378 to 406 bp. The ITS2 sequences were aligned using Clustal W, genetic distances and phylogenetic tree were calculated using MEGA V7.0. rDNA-ITS2 sequences of 37 specimens of Trichogramma confirmed in GenBank in the study. Also, secondary structures of ITS2 sequences were predicted with the help of Mfold web server. All secondary structure constructions were performed at 37 °C using RNA version 2.3 default parameters. Conclusions A molecular marker can be used successfully to distinguish closely related groups if it is a rapidly evolving and highly conserved gene region. In the study, it was shown that ITS2 was a reliable molecular marker in distinguishing species. Therefore, with rDNA-ITS2 sequence analysis, Trichogramma spp., which is a very important natural enemy in biological control, has been identified.