Thieves of thorns and thickets: Investigating the diversity of agastoparasite genus, Synophromorpha, Ashmead,1905

Gall wasps (Cynipidae, sensu lato) are a lineage of about 1400 species, most of which induce abnormal growths on plants, referred to as galls, which protect and nourish their developing larvae. Galls serve not only as habitats for the cynipid inducer but also a diverse ecosystem of associates, including arthropod parasitoids, hyperparasitoids, and inquilines. Inquilines, many of which are also cynipids, are species who cannot induce galls of their own but instead usurp pre-existing galls.

Early gall researchers hypothesized that inquiline cynipids evolved from inducers, and they lumped all inquiline species into a single tribe: Synergini. Under this assumption, Ronquist coined the term “agasto-parasites” for species that are in the same monophyletic genus, tribe, or family as their host and have evolved together in close association. Contemporary studies, using genetic data, found Synergini to be polyphyletic, which led to the inquilines being split into multiple tribes, most of them far removed from their hosts. However, there is still one lineage where the title agasto-parasite remains appropriate, the inquilines of the tribe Diastrophini in the genus Synophromorpha. These agasto-parasites attack woody galls on Rubus (Rosaceae), induced by their sister genus Diastrophus. Our preliminary data have revealed several new species of Diastrophus in the Nearctic, which have not been evaluated for the presence of inquilines. Here we revisit the host ranges of the Nearctic Synophromorpha and highlight new species awaiting description using DNA barcodes of the mitochondrial cytochrome oxidase 1(CO1) gene and morphological data from each species and host.