New distribution and molecular diversity of the reniform nematode Rotylenchulus macrosoma Dasgupta, Raski and Sher, 1968 (Nematoda: Rotylenchulinae) in Europe.

Reniform nematodes of the genus Rotylenchulus are semiendoparasites of numerous herbaceous and woody plant roots and occur largely in regions with temperate, subtropical and tropical climates. In this study, we provide new records of the nematode R. macrosoma in eight European countries (Czech Republic, France, Germany, Hungary, Italy, Romania, Serbia and Portugal), in addition to the six Mediterranean countries (Greece, Israel, Jordan, Spain, Syria, and Turkey) where it has previously been reported. Four new host species (corn, pea, wheat and an almond-peach hybrid rootstock) are added to the recorded host species (bean, chickpea, hazelnut, peanut, soybean, wild and cultivated olive). Molecular analyses based on the coxI and D2-D3 segments of 28S RNA markers showed high diversity and pronounced genetic structure of populations of R. macrosoma. However, the complexity of phylogeographic patterns in plant-parasitic nematodes may be related to the intrinsic heterogeneity in the distribution of soil organisms, a rare occurrence of a species, or the potential human impact associated with agricultural practices.