bioRxiv preprint doi: https://doi.org/10.1101/274431; this version posted March 22, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 1 Quantifying the unquantifiable: 2 why Hymenoptera – not Coleoptera – is the most speciose animal order 3 4 Andrew A. Forbes, Robin K. Bagley, Marc A. Beer, Alaine C. Hippee, & Heather A. Widmayer 5 University of Iowa, Department of Biology, 434 Biology Building, Iowa City, IA 52242 6 7 Corresponding author: 8 Andrew Forbes 9 10 Email address:
[email protected] 11 12 13 1 bioRxiv preprint doi: https://doi.org/10.1101/274431; this version posted March 22, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 14 Abstract 15 Background. We challenge the oft-repeated claim that the beetles (Coleoptera) are the most 16 species-rich order of animals. Instead, we assert that another order of insects, the Hymenoptera, 17 are more speciose, due in large part to the massively diverse but relatively poorly known 18 parasitoid wasps. The idea that the beetles have more species than other orders is primarily based 19 on their respective collection histories and the relative availability of taxonomic resources, which 20 both disfavor parasitoid wasps. Though it is unreasonable to directly compare numbers of 21 described species in each order, the ecology of parasitic wasps – specifically, their intimate 22 interactions with their hosts – allows for estimation of relative richness.