News Finding: New paper in Science estimates that for every mammal species in a rainforest, there are 300 arthropod species. 
Paper Finding: Reassuringly, our wellresolved estimates of tropical arthropod species richness are of the same order of magnitude as prior estimates (table S3) , adding credence to recent estimates of tropical arthropod diversity (5, 21) .
News Context: New paper in Science estimates that for every mammal species in a rainforest, there are 300 arthropod species. 
Paper Context: Because this study targeted the full spectrum of arthropods, it offers a comprehensive test of previous estimates of species richness based only on selected guilds or taxa. Reassuringly, our wellresolved estimates of tropical arthropod species richness are of the same order of magnitude as prior estimates (table S3) , adding credence to recent estimates of tropical arthropod diversity (5, 21) . Although the scope for direct comparison is limited because of regional differences in sampling effort, lowland tropical forest in Panama seems to support 2.1 to 8.4 times as many arthropod species as observed in temperate forests (table S3) .