This Systematics Association Special Volume is the result of a symposium entitled, ‘Cryptic taxa - artefact of classification or evolutionary phenomena?’ held on June 17 as part of the Association’s 10th Biennial Meeting 2019. I began to realise that the notion of cryptic species touches the heart of several major debates in biology, including, ‘what are species?’, ‘how should we recognize them?’, the notion of punctuated equilibria and that of morphological stasis in the fossil record. Also, in the midst of a biodiversity crisis the phenomenon of cryptic species suggests that there may be a greater diversity of evolutionary lineages in need of conservation than has been suggested. The chapters that emerged from the Symposium show clearly how the topic of 'species' remains central to biodiversity sciences and the subject of wide-ranging and lively debate. In almost every chapter there is a call for change, either of direction or for the inclusion of new developments and data, and their focus ranges from abandoning species altogether to highlighting the weaknesses in current taxonomic process suggesting that our representation of the biological universe is still a chaotic torso.