Evidence for extensive cryptic speciation in trematodes of butterflyfishes (Chaetodontidae) of the tropical Indo-West Pacific

- Sixteen morphospecies were analysed from six Indo-Pacific sites using cox1 and ITS2 DNA.
- All morphospecies were distinguished by cox1 and ITS2 data.
- Intraspecific variation between localities was found in eight species.
- Intraspecific variation was sometimes greater than interspecific variation.
- Overall there is a continuum of genetic variation within and between species.