This is an interesting topic, because organisms can be heavily studied in one context and under-represented in another. For example, a taxon may be well-studied by taxonomists but only weakly represented in a DNA barcode library. Or, the opposite may be true -- a molecular biodiversity survey may reveal many possible cryptic species long before morphological taxonomists can determine whether there is independent support for formally identifying new species. Also, unrecognized under-representation might even contribute to identification errors. Whether we're building phylogenetic trees from molecular data or analyzing informative morphological differences, we can miss sources of diversity when we can't compare enough specimens or populations to be sure of the discontinuities.