Figure 1 from: Oliveira I, Read V, Mayer G (2012) A world checklist of Onychophora (velvet worms), with notes on nomenclature and status of names. ZooKeys 211: 1-70. https://doi.org/10.3897/zookeys.211.3463

Figure 1 - Diagram illustrating the number of species descriptions of Onychophora per year since the very first description of an onychophoran species by Guilding (1826). Note the numerous gaps in the taxonomical work.