Without abundant material it were ridiculous to attempt a wide revision of these insects; and ... a mass of this material causes one's courage to sink at the sight of so uniform and apparently characterless a group.
Claude Morley, 1912
Back in 1912, three species of the parasitic wasp genus Ophion were described by two different entomologists, one of them was Claude Morley. This increased the number of known species in North America to eleven. Since then no new species was described although it has long been known that the actual diversity must be much higher. Everyone simply assumed that Ophion are just too difficult to tell apart and therefore didn't bother to face the challenge of sorting them out.
However, with the advent of new taxonomic tools, it is no longer necessary to rely solely on the challenging morphology of the group. In a newly published study two Canadian colleagues used a combination of molecular and morphometric methods to define a new species group within Ophion, and to delimit and describe six new species within this group. The molecular work involved the analysis of three different genetic markers (ITS2, COI, and 28S D2-D3), while the morphometric analyses included both an analysis of wing venation and a more traditional approach of measuring various body parts.
All the different methods used provided remarkably congruent results, which gave the authors a lot of confidence in the new species they described. This also reemphasizes the point that all these new methods are essentially a new toolkit for studying species in morphogically-challenging groups. Not a very surprising new message for the hard-core DNA Barcoding researcher but good news nevertheless.
... we have shown that by using an iterative analysis of morphology, molecular analysis and morphometrics, we can delimit and describe species within a genus that is so morphologically challenging that no new species have been described in North America for more than a hundred years. Furthermore, molecular and morphological recognition of this species group will now allow more targeted specimen collection and museum research, supporting a global revision of the species group in its entirety.
We are only at the beginning of understanding the real diversity of parasitic wasps and there are already researchers who think that we might need to change our perception of the beetles and butterflies being the most diverse insect groups. Actually, the order hymenoptera might be much larger than both of them. One indication of that is the recent flood of new species described as the result of studies utilizing new tools such as DNA Barcoding to delineate them.