Summary statistics for the CAOS analyses of the problematic groups at the species level.

Each of the investigated species showed intraspecific variation above 2%, suggesting that DNA barcoding may be hampered by the lack of a distinct barcoding gap. However, each of the different lineages within these species groups possesses diagnostic characters that can aid in the future identification of the lineages (no diagnostic characters where found when comparing the sequences to the entire pool of nemertean taxa; see text for discussion).