Table 1 A brief introduction to the challenge of leech taxonomy

The relative phylogenetic relationships of the genus Haemadipsa that result from maximum likelihood analysis of combined cox1 and cox3 mitochondrial data (Fig. 2) reveal a variety of challenges associated with the use of iDNA. The proper identification of species in the family Haemadipsidae relies both on internal sexual characteristics [72, 76, 77] and on external patterns in color, annulation and eyespot arrangements [20, 73, 74]. Consequently, field collection with rapid assessment are limited to the designation of morphospecies; aggregations of specimens that look, but are not necessarily genetically, alike. Species assignments and delimitations on the basis of DNA barcodes necessarily are predicated on the accuracy and precision of the information available in public databases [75, 80]. Both of these desiderata are undermined by incomplete coverage across taxonomic groups of interest, by the persistence of misidentified isolates in public databases, by the existence of undiscovered diversity and by cryptic species.