شناسایی ریخت‌شناختی و مولکولی گونه‌های Sectonema heynsi،Sectonema demani و Epacrolaimus declinatoaculeatus از استان آذربایجان شرقی

During 2016 and 2017, for identification of species diversity of the two genera, several soil samples were collected from the vegetation rhizosphere soil of East Azarbaijan province. The extraction of the nematodes, killing, fixing and microscopic slides preparation were carried out using the nematology techniques. The extracted nematodes were identified based on morphological and morphometric characteristics. In the molecular section, DNA of the nematodes was extracted and D2-D3 segment of 28S rDNA amplified. The amplified fragment was sent for sequencing and phylogenetic tree was drawn by MrModel test 2.3 and Mrbayes softwares. As the results, three species, S. heynsi , S. demani and Epacrolaimus declinatoaculeatus were identified. The two former species are new reports for nematode fauna of Iran. This is also the first record of the males of the two species of Sectonema. These two species are very similar in terms of morphometric data and their distinct difference is the presence of setae-like structures around the oral opening of the S. heynsi and absence in S. demani. Also, the number of ventromedian supplements and the length and width of the spicules can be considered as the most important distinctive factors of these species. Sectonema heynsi is differentiated from S. demani, by the number of supplements (7-13 vs. 4-5), spicules length (145-160 vs. 120-125 μm) and width (46-44 vs. 31-33 μm). Epacrolaimus declinatoaculeatus differs from E. imperator in terms of more curving of the dorsal part of odontostyle and shorter odontostyle, stronger vagina and different arrangment of the supplements. The analysis of molecular data confirmed the identification results based on morphological and morphometrical data and showed that the two species of the genus Sectonema, are located along with other known species of this genus. Also, the genus Epacrolaimus has a closely phylogenetic relationship with the genus Sectonema and they are located in the closest relationship in the obtained phylogenetic tree. The sequence of amplified gene section D2-D3 28S rDNA by primers in S. heynsi and E. declinatoaculeatus is recorded for the first time and deposited in the Gene bank.