Genetic relationships among species of Contracaecum Railliet & Henry, 1912 and Phocascaris Host, 1932 (Nematoda: Anisakidae) from pinnipeds based on mitochondrial cox2 sequences, and congruence with allozyme data

The genetic relationships among 11 taxa, belonging to the genus Contracaecum (C. osculatum A, C. osculatum, B, C. osculatum (s.s.), C. osculatum D, C. osculatum E, C. osculatum baicalensis, C. miroungo, C. radiatum, C. ogmorhini (s.s.), C. morgolisi) and Phocoscaris (Phocascaris cystophoroe), parasites as adults of seals, were inferred from sequence analysis (5 19 bp) of the mitochondrial cytochrome c oxidase subunit 11 (mtDNA cox2) gene. Phylogenetic analyses obtained from Parsimony (MP) and Neighbour-joining (NJ) K2P distance values generated similar topologies, each well supported at major nodes. All analyses delineated two main clades: the first encompassing the parasites of the phocid seals, i.e. the C. osculatum species complex, C. osculatum baicalensis, C. miroungo and C. radiatum, with the latter two species forming a separate subclade, the second including the parasites of otarids, i.e. C. ogmorhini (s.s.) and C. margolisi. An overall high congruence between mtDNA inferred tree topologies and those produced from nuclear data sets (20 allozyme loci) was observed. Comparison of the phylogenetic hypothesis here produced for Contracaecum slap. plus Phocascaris with those currently available for their definitive hosts (pinnipeds) suggests parallelism between hosts and parasite phylogenetic tree topologies.