Molecular and morphological identification of some oligochaete species as indicator for ecological diversity of the Hilla River in Babylon Province-Iraq

The present study was carried out in Hilla river for the identification of Oligochaetes using morphological and molecular methods. The morphological study confirms the identification of five species (Aulodrilus pigueti, Branchiura sowerbyi, Eiseniella tetraedra, Limnodrilus hoffmeisteri, Stylaria lacustris) using scanning electron microscope (SEM) technique. Out of all species, Eiseniella tetraedra received the greatest percentage of density (55.19 %). Their diversity was assessed using several indices. Value of Shannon-Wiener index ranged between 0.23-0.93 and that of, Simpson index ranged between 0.32-0.91. The results of these and other biodiversity indicate the presence of environmental stress. Mitochondrial cytochrome c oxidase subunit I (COI) region was amplified and sequenced to find the similarity and variations among species and confirm the diagnosis of species (Paranais litoralis, Paranais frici, Stylaria lacustris, Monopylephorus rubroniveus, Tubifex tubifex) and all sequence and strains matched to the complete genetic content of the samples at the NCBI to ensure the results. This study is considered the first study for the diagnosis of oligochaetes in the middle Euphrates region by using the molecular technique to confirm the identification of numerous unrecorded species that share morphological characteristics with other species, making it challenging to categorize them morphologically.