Neither molecular nor morphological data have all the answers; with an example from Macrobrachium (Decapoda: Palaemonidae) from Australia

Much controversy still seems to surround the role of molecular data in general, and DNA barcoding in particular, within the taxonomic community. This has lead to numerous “call and response” pairs of papers, most recently Ebach (2011) and Mitchell (2011), but preceded by many other pairs, such as Packer et al. (2009) and Hołyński (2010). There have been numerous calls for a more “integrative” approach to taxonomy (Mitchell 2011; Stevens et al. 2011), which itself has generated point and counterpoint papers (Dayrat 2005; Valdecasas et al. 2008). This of course is how science progresses (although Max Planck suggested that science advances “one funeral at a time”, en.wikiquote.org/wiki/Max_Planck, accessed 20 March 2011). If one looks carefully at many of these papers, there is almost always an acknowledgement of the utility of the “other” type of data, such as “We emphasize that DNA barcoding is not a substitute for conventional taxonomic approaches” (Costa et al. 2007) or “Sometimes molecular analysis may be the most convenient way to clarify the taxonomical assignments between sexes, developmental stages, castes etc.” (Hołyński 2010). Surely, eventually a point is reached when, to paraphrase U2’s Bono, “There's been a lot of talk about this, maybe too much talk” (Under a Blood Red Sky, 1983), and perhaps we should all just get on with it. It seems pretty obvious to us that both types of data are extremely useful, have their own strengths, weaknesses and purviews (with some overlap), and one would be foolish to ignore either of them out of hand. Both DNA barcoding and morphological descriptions are often the tip of the scientific iceberg and a starting point for further scientific analyses. Neither morphological characters nor DNA sequences fully define a living, breathing biological organism, any more than your passport photo fully reflects you.