The Taxonomic Position and Phylogenetic Relationship between Digramma interrupta and Ligula intestinalis Based on Morphological and Molecular Diagnosis

The position of remains disputable as it was raised by Cholodkovsky from . This study aimed to survey the evolutionary relationships and the taxonomic position of and . It also intended to support or reject the validity of as an independent genus and its correlation with on the basis of their morphological characteristics and a study on molecular data. Overall, 1301 fish varieties, including 883 and 418 , were collected from north and north-western parts of Iran. samples were obtained from fresh water sources of the Maragheh dam (northwest) and the Ramesar Lake (north). Moreover, samples of were captured from the Aras Dam (northwest) and the Bandar-e-Anzali lagoon (north). PCR was used to generate a fragment spanning two independent ITS-inclusive parts: ITS1-5.8S and ITS2 with two pairs of primers. Nucleotide variation between and samples amounts to about 3% to 7%. Between samples of and GenBank data, and also between specimens and GenBank data, the diversity was seen for about 1% to 3%. Moreover, about 1% to 4% nucleotide variation was seen only in samples caught from the same host, which could be supplementary to the presence of a species and/or strains in this genus. Maybe was just a rare diplogonadic form of the species, not a different genus and not synonymous with the genus, but only another species of the genus.