Members of the genus Anisakis are parasitic nematodes of the family Anisakidae.
They are potential zoonotic parasites, causing anisakiasis in humans who consume raw or
undercooked seafood (fish or squid) infected with the larvae of this nematode. In the present
study, anisakid nematodes collected from the marine fish Priacanthus tayenus (Purplespotted
big-eye) caught from the Gulf of Thailand were examined morphologically and
characterized genetically by DNA sequence analysis. Sequence data from the mitochondrial
cytochrome c oxidase subunit II (mtDNA cox2) gene were used to identify these nematodes
to species level and to evaluate the phylogenetic relationship among various taxa. All the 15
third-stage larvae of Anisakis nematodes investigated in this study belonged to the same
genetic lineage as the A. typica species complex (named here as A. typica sp. T – T for
Thailand). Eight mtDNA cox2 haplotypes were revealed in the 15 isolates of this Anisakis
from Thailand. The mtDNA cox2 haplotypes of A. typica sp. T from Thailand were genetically
distinct from those of the A. typica sensu stricto. Taxonomic description of this A. typica sp.
T as a distinct species however awaits the availability of adult specimens.