Minimalism is in: two new Diastrophus (Hymenoptera: Cynipidae) species inducing inconspicuous galls on cinquefoils (Rosaceae: Potentilleae), with evaluation of the extended phenotype across gall wasps

While the majority of galling insects induce visible alterations to their host plants, there are many species that induce inconspicuous galls, changing only the internal structure of the host plant. There has been no comprehensive investigation into the prevalence of this extended phenotype. We compile a list of gall wasps (Hymenoptera: Cynipidae) that induce inconspicuous galls and describe two new species–Diastrophus ertterae Davis & Nastasi sp. n. and D. moniquae Davis & Nastasi sp. n.–from galls on the cinquefoil species Potentilla gracilis in western North America and P. simplex in eastern North America (Rosaceae), respectively. These new species are supported by morphological, molecular and ecological (host plant and gall) data. We discuss the implications of these species’ discovery on the overall diversity of Diastrophini and our understanding of the evolution of the tribe. Following the discovery of these species, a literature search revealed 111 known gall wasp species that induce inconspicuous galls, a proportion that could grow with continued investigation of this life history trait. We also review terminology commonly associated with inquilines, many of which could also be considered to be inducers of inconspicuous galls. http://www.zoobank.org/urn:lsid:zoobank.org:pub:14AF8CE9-335E-4D59-91C9-0CC79B2E1F55 https://zoobank.org:act:27730460-735D-4527-A1E8-A70A676B04A5.