An integrative approach to distinguishing taxonomically challenging microhymenoptera: Eurytomidae (Hymenoptera: Chalcidoidea) associated with cynipid galls on rose.

iii Abstract Cynipid wasps of the genus Diplolepis Geoffrey induce galls exclusively on roses. These galls are susceptible to attack by various hymenopteran parasitoids, the most common of which are members of the family Eurytomidae, with 10 described species having been recorded in association with rose galls in Canada. Because of their small size, sexual dimorphism, morphological plasticity and poorly known biology, species identification of eurytomids is often uncertain. This thesis focused on identifying the eurytomids associated with the galls of the 14 native species of Diplolepis in Canada, testing species limits using a combination of morphological, mitochondrial DNA cytochrome c oxidase I (COI), ecological and geographical data. Six morphospecies were identified using morphological characters, while molecular data identified eight haplogroups. COI sequences identified one species of Tenuipetiolus Bugbee and seven species of Eurytoma Illiger, all associated with galls induced by Diplolepis in Canada. Inconsistencies were observed when compared to morphospecies, including four haplogroups within the genus Eurytoma that were overlooked by morphological studies. The morphospecies Eurytoma acuta Bugbee is a junior synonym of Eurytoma discordans Bugbee; however, the high intraspecific genetic divergences suggest the existence of a species complex. Two geographically sympatric but genetically distinct haplogroups were found within the morphospecies Eurytoma spongiosa Bugbee, “E. spongiosa 2” being a new species that was previously overlooked. An identification key along with (re)descriptions of all identified species was provided. This integrative taxonomy approach confirmed the oligophagous nature of most eurytomids, and provides new insight into the life history strategies of these parasitoids.Master of Science (M.Sc.) in Biolog