Integrative characterization and phylogenetic relationships of Xiphinema rivesi and X. pachtaicum (Nematoda, Longidoridae) associated to vineyards in North Italy

The occurrence of Xiphinema species in the rhizosphere of vineyards showing general decline phenotype in North Italy was investigated. Most of the collected soil samples contained two Xiphinema species belonging to X. americanum-group, along with X. index. Using the integrative taxonomy approach, combining morphological, molecular and multivariate morphological analyses, the two populations of the X. americanum-group were identified as X. rivesi and X. pachtaicum. Furthermore, one male specimen of X. rivesi was recovered and the presence of three juvenile developmental stages was confirmed based on the scatter diagram. D2-D3 expansion domains of LSU, ITS region and partial COI were used to determine the phylogenetic relationships of the two Xiphinema species from North Italy with other species belonging to X. americanum-group. Five other Xiphinema populations from different geographical areas were included in this study and only molecularly identified as X. rivesi, X. pachtaicum and X. incertum by sequencing the ITS and D2-D3 expansion domains of LSU rDNA.