More taxonomists describing significantly fewer species per unit effort may indicate that most species have been discovered

Recent studies show that there are more taxonomists describing species in recent decades than before. However, whether the rate of increase in number of taxonomists is greater than the rate of new species description has been questioned. We found a statistically significant decline in the proportion of species being described per number of taxonomists (i.e. authors of recent species descriptions) during the past century for (a) families of insects that had been stated not to show this trend, and (b) a sample of over 0.5 million marine, terrestrial and freshwater species. We suggest that this decreased ‘catch’ of species per taxonomic effort, despite scientists’ greater ability to explore and sample habitats, means it is getting harder to discover new species, and supports recent studies suggesting that two-thirds of all species have been named.