Eupelmus, Dalman, 1820

Eupelmus View in CoL ( Macroneura Walker ) is a cosmopolitan subgenus of parasitoid wasps, although the group was most likely absent from Australasia prior to human expansion because it is represented there by only two widespread species ( Bouček, 1988). The circumscription of the subgenus and its synonymy can be found in

* E-mail: lucfusu@hotmail.com

[ Version of Record published online 31 October 2017; http://zoobank.org/ urn:lsid:zoobank.org:pub:B62DEBA7-C041-49E3-BAD0-CA9BE873AD34 ]

Gibson (1995). In the Palaearctic region, the group is most specious in Southern Europe and North Africa, with 13 currently recognized species, of which seven have been recorded from Europe ( Kalina, 1981). While the Palaearctic members of Eupelmus Dalman , subgenus Eupelmus , were recently revised in a series of two papers ( Al khatib et al., 2014; Gibson & Fusu, 2016), members of the subgenus Macroneura have not yet been reassessed under an integrative taxonomic approach.

Eupelmus (Macroneura) vesicularis (Retzius) View in CoL is one of the first species of chalcid wasps ever described ( Retzius, 1783). It was named even before the general acceptance of the binomial Linnaean system, under the alternative naming system of Baron Charles de Geer, as ‘ Ichneumon View in CoL non-ailé à deux vessies mobiles’ [wingless Ichneumon View in CoL with two mobile vesicles] ( De Geer, 1771). It is worthwhile mentioning that De Geer’s observations—despite being made on a minute species in the 18th century—were so accurate that he even gave an account of the peculiar mechanics of jumping in Eupelmidae View in CoL , only explained in detail some 200 years later by Gibson (1986). De Geer described the jump of E. vesicularis View in CoL almost correctly, as driven by curving the body and pushing the ventral part with force into the ground: ‘il m’a semblé pourtant qu’il l’exécute [the jump] en courbant le ventre et en le poussant avec force contre le plan de position’ [however it seemed to me that it performs the jump by bending the middle and pushing it strongly against the plane of position] ( De Geer, 1771: 910). Eupelmus vesicularis View in CoL (s.l.) is one of the most widespread species of Eupelmidae View in CoL in Europe. It is also common in North America, but here it was accidentally introduced by European settlers prior to the 19th century ( Bouček, 1977; Gibson, 1990). It is also the only species of the subgenus in New Zealand ( Bouček, 1988), which indicates another introduction. It is considered as one of the most polyphagous chalcid wasp species ( Gahan, 1933), with at least 230 hosts from four insect orders and 43 families recorded in the literature for E. vesicularis View in CoL s.l. ( Noyes, 2015). Askew et al. (2006, 2013) and Fusu (2010) can be consulted for the latest additions to hosts in Europe. Among its economically important hosts are the Hessian fly Mayetiola destructor (Say) View in CoL and the jointworms (larvae of Tetramesa spp. ), both destructive pests of wheat ( Phillips & Poos, 1927), the cabbage seedpod weevil Ceutorhynchus obstrictus (Marsham) ( Gibson, Gates & Buntin, 2006) View in CoL , and the house fly Musca domestica Linnaeus ( Smith & Rutz, 1991) . It can also act as a hyperparasitoid and as such not always beneficial relative to control of such pests. Another intriguing biological aspect of the species is that only females are known from North America ( Graham, 1969; Gibson, 1990; Fusu, 2010) and apparently also Australasia, but both sexes occur in Europe, and for some time the situation in North America was even generalized for the whole distribution range ( Gahan, 1933; Hedqvist, 1963).

Because of biological and morphological variability, the possibility of more than one species was suspected under what historically had been interpreted as E. vesicularis View in CoL . This was recently confirmed using allozyme electrophoresis, morphometry and host preference data, which indicated the presence of two cryptic species that were informally named ‘ Eupelmus vesicularis View in CoL dark form’ and ‘ E. vesicularis View in CoL light form’ by Fusu (2010). Taxonomic changes were not proposed in the latter paper because the study of the types of taxa synonymized under E. vesicularis View in CoL was a necessary prerequisite. As discovered by the present study, neither of the two species differentiated by Fusu (2010) is in fact E. vesicularis View in CoL . In order to resolve the Eupelmus vesicularis View in CoL complex in the broader context of the European species of E. ( Macroneura View in CoL ), the present study used an integrative approach employing molecular data, cytogenetics, morphometry, morphology, wing interference pattern in males (WIP) and specimens from a broad geographic area. Many recent studies have shown the efficiency of DNA-based molecular methods in accelerating the discovery of new species ( Fernández-Triana et al., 2013, 2014; Smith et al., 2013), species recognition ( Armstrong & Ball, 2005), linking sexes in extremely sexually dimorphic species ( Fisher & Smith, 2008), sorting out species complexes and discriminating between pairs of cryptic species ( Bernardo et al., 2008; Gebiola et al., 2009; Veijalainen et al., 2011; Al khatib et al., 2014, 2015). For example, cytochrome oxidase c subunit I (COI) in combination with the 28S-D2 expansion segment was used with success to discriminate between closely related species of Eurytoma Illiger ( Delvare et al., 2014) View in CoL , Necremnus Thomson ( Gebiola et al., 2015) View in CoL and Encarsia Förster ( Gebiola et al., 2016) View in CoL . Phenotypic discontinuities that could indicate potential species are often very difficult to assess correctly because of seemingly continuous variation, but may become apparent once specimens are separated molecularly ( Gebiola et al., 2015); hence, this approach is well suited to E. ( Macroneura View in CoL ), especially the vesicularis View in CoL complex. Cytogenetics is frequently used to characterize and separate vertebrate species and insect groups such as Diptera and Orthoptera View in CoL , but can also be used to differentiate cryptic species of parasitic wasps. A good example is Gokhman, Timokhov & Fedina (1998), who showed that the name Anisopteromalus calandrae (Howard) View in CoL ( Pteromalidae View in CoL ) represented two different species that are very close morphologically, but have different karyotypes and life strategies, one of them being formally described recently by Baur et al. (2014). Gokhman (2006, 2009) reviewed the known cases of sibling species detection in parasitic Hymenoptera View in CoL using cytogenetic data. Morphometry, including principal component analysis, is another useful tool used alone or in combination with one or more of the above-mentioned techniques to discriminate cryptic species ( Bernardo et al., 2008; Peters & Baur, 2011; Popovici et al., 2011, 2013a, b; László, Baur & Tóthmérész, 2013). The recent discovery of wing interference patterns (WIPs) indicated that this could be involved in intra- and interspecific signalling (Shevtsova et al., 2011) as part of the mate recognition system, and hence potentially important for separating closely related species. There is no overwhelming evidence of this yet, but WIPs are sexually dimorphic and/or distinct between species in several species of Achrysocharoides Girault View in CoL ( Eulophidae View in CoL ) ( Hansson & Shevtsova, 2010; Shevtsova & Hansson, 2011), and in Watshamia Bouček View in CoL ( Pteromalidae View in CoL ) WIPs are distinct between males of different species ( Mitroiu, 2013).

While revising Eupelmus (Macroneura) (as a genus), Kalina recognized two subgenera: Macroneura s.s. and Euronmacra Kalina. These two names are here used without rank to designate two clades. In this paper, I recognize a species complex of morphologically very similar species ( E. vesicularis complex) that, under the currently accepted taxonomy, all fall within Eupelmus (Macroneura) vesicularis s.l. ( Fusu, 2010).