Novel polymorphic microsatellite loci in Anisakis pegreffii and A. simplex (s. s.) (Nematoda: Anisakidae). Implications for species recognition and population genetic analysis

The species of Anisakis constitute one the most widespread groups of ascaridoid nematodes in the marine ecosystem. Three closely related taxa are recognized in the A. simplex (s. l.) complex, i.e. A. pegreffii, A. simplex (s. s.) and A. berlandi. They are distributed in populations of their intermediate/paratenic (fish and squids) and definitive (cetaceans) hosts. A panel of seven microsatellites loci (Anisl 05784, Anisl 08059, Anisl 00875, Anisl 07132, Anisl 00314, Anisl 10535, Anisl 00185), were developed and validated on a total of N= 943 specimens of A. pegreffii and A. simplex (s. s.), collected in fish and cetacean hosts from allopatric areas within the range of distribution of these parasite species. In addition, the locus Anisl 7, previously detected in those Anisakis spp., was investigated. The parasites were first identified by sequence analysis of the EF1 α-1 nDNA. The panel of the microsatellites loci here developed have allowed to: i) detect diagnostic microsatellite loci between the two species; ii) identify specimens of the two species A. pegreffii, A. simplex (s. s.) in a multi-marker nuclear genotyping approach; iii) discover two sexlinked loci in both Anisakis species; iv) estimate levels of genetic differentiation at both the interand intra-specific level.