Testing species limits of Eurytomidae (Hymenoptera) associated with galls induced by Diplolepis (Hymenoptera: Cynipidae) in Canada using an integrative approach

Abstract

Studies of insect host-parasitoid relationships are often confounded by the difficulties associated with species delimitation in taxonomically challenging groups. Eurytomidae (Hymenoptera) are common parasitoids associated with galls induced by Cynipidae (Hymenoptera) and are difficult to identify due to their small size, morphological conservatism, and unreliable published host records. This study tests the species limits of eurytomids associated with galls induced by Diplolepis Geoffroy (Hymenoptera: Cynipidae) in Canada using an integrative taxonomy approach including adult morphology, the mitochondrial gene cytochrome c oxidase I, host records, and geographical range. Incongruences between morphological and molecular data were found within the Eurytoma discordans Bugbee complex, as Eurytoma discordans, Eurytoma acuta Bugbee, and Eurytoma calcarea Bugbee were shown to be new synonyms. The results also revealed the presence of cryptic species within Eurytoma spongiosa Bugbee. Furthermore, issues that have impeded ecological and biological studies of eurytomids associated with rose galls such as host specificity and sex association were resolved using DNA barcodes, providing new insights into the evolutionary history of this difficult group.

Revision of Canadian Eurytomidae (Hymenoptera, Chalcidoidea) associated with galls induced by cynipid wasps of the genus Diplolepis Geoffroy (Hymenoptera, Cynipidae) and description of a new species

“…Upon examining additional materials it was noted that the degree of infuscation on legs and scape are variable within this species and thus cannot be used as reliable distinguishing characters. The molecular evidence presented in Zhang et al (2014) also support the monophyly of this group, albeit with the highest intra-specific divergence compared to other eurytomids. Considering there are no distinct geographical or host differences that support three distinct species, E. acuta and E. calcarea along with their associated subspecies were synonymized under E. discordans pending further molecular or ecological studies.…”

“…Few consistent morphological differences were found between E. imminuta and E. spongiosa (identified in Zhang et al 2014 as E. spongiosa 1, and E. spongiosa 2, respectively) despite deep divergence in COI sequences and differences in host records (Zhang et al 2014). Considering there are examples of other members of the Eurytoma rosae species group having been identified as genetically distinct but morphologically indistinguishable (Ács et al 2002(Ács et al , Gómez et al 2011, the two species are therefore considered as distinct.…”

“…The objective of this study is to describe both male and female eurytomids associated with rose galls in Canada, as well as updating morphological characters, hosts, and distributional records following the molecular study using COI (Zhang et al 2014). Additionally, a dichotomous key is provided for both sexes of all seven species.…”

“…This species is likely a predator of inquiline Periclistus rather than the gall inducer, as they are reared from hosts that have a high rate of inquilism (Zhang et al 2014). Eurytoma iniquus is particularly abundant in Periclistus-modified galls induced by D. nodulosa, which are morphologically distinct from unmodified galls (Shorthouse 2010).…”

“…Bugbee (1951a, b) reported 12 species of Eurytoma Illiger and one species of Tenuipetiolus Bugbee known from galls of Diplolepis, and suggested that most species are monophagous. Little is known about the host specificity of eurytomids in galls of the 14 species of Diplolepis found in Canada, but all species of Diplolepis are host to at least one species of Eurytoma (Shorthouse 2010, Zhang et al 2014.…”