Occurrence of Xiphinema santos Lamberti, Lemos, Agostinelli & D’Addabo 1993 (Nematoda: Longidoridae), a X. americanum-group member in Iran

Abstract

A population of Xiphinema americanum-group was recovered in association with stone fruit trees in Isfahan province, center of Iran. A reverse taxonomic approach based upon the large subunit ribosomal DNA (LSU rDNA D2-D3) and the mitochondrial cytochrome c oxidase subunit I (COI mtDNA) gene sequences in integration with morphological studies, revealed that the recovered population belongs to Xiphinema santos. The Iranian population was mainly characterized by 1240–1868 μm long females with 60–84 μm long odontostyle, a = 37.2–51.9 and c = 42.8–54.6. It is further characterized by a lip region having a depression in junction with the body, presence of visible endosymbiont bacteria in ovaries under light microscope, dorsally convex and ventrally slightly concave conical tail with a blunt tip and three juvenile developmental stages. This population was similar to the type population in its morphology; however overlapped and extended morphometric data ranges, as well as differences in some indexes were observed. Compared to a Spanish population of this species, the Iranian population had a close morphology, similar morphometric data ranges and identical LSU and COI sequences. In LSU phylogeny, the relationship between the present and some previously sequenced isolates of the species and some isolates of three species X. georgianum, X. laevistriatum and X. citricolum was not resolved. In COI phylogeny, the clade of the Iranian and Spanish populations appeared as an independent lineage inside an unsupported clade including several species. The comparison with other populations of the species was reported and discussed. A second species, X. primum, that is native to Iran, was recovered from a new locality and characterized molecularly.