Illidops Mason 1981

Genus Illidops Mason, 1981 Illidops Mason, 1981: 56 (type species: Illidops butalidis (Marshall, 1889: 45), by subsequent designation by Mason 1981: 56) Diagnosis The genus Illidops can be defined at present by its posterior smooth band of the scutellum interrupted centrally by a sculptured area (Fig. 2A–E; although in very few species the sculpture is very weak, mostly limited to a small area on the anterior margin of the mesoscutellar bar or only consists of punctures, Fig. 2F–I); fore wing with vein R1 shorter than pterostigma (~0.3–0.9× (e.g., Figs 6G, 10F, 12F, 20F), with the exception of I. kostylevi (Kotenko, 1986) having R1 as long as the pterostigma (Fig. 25E)), although a few species in the morphologically similar genera Apanteles, Dolichogenidea and Rhygoplitis share this character; propodeum usually strongly sculptured, sculpture mostly reticulate (e.g., Figs 6E, 12D, 31D 48E, 52D; although a few species may have a median, longitudinal carina in addition to the reticulate sculpture (Figs 36A–D, 53C) and some other species may have variously reduced sculpture (e.g., Figs 10E, 25D, 26D, 38C, 56E, 58D, 61D), in extreme cases having an almost entirely smooth propodeum (Figs 19D, 22C)); hind wing with entirely setose vannal lobe (in most species, e.g., Figs 33F, 50H); eyes convergent, at times strongly (Fig. 3A–B; but many species just very slightly convergent (Fig. 3C) or with parallel eyes (Fig. 3D)); T3–T7 medially desclerotized and seemingly pushed forwards (e.g., Figs 6F, 12E, 14E, 28E; although some species do not have this feature and some species in the morphologically similar genera Apanteles, Dolichogenidea and Rhygoplitis share this character). Remarks Knowledge on the potential monophyly of Illidops or its relationship towards the morphologically similar genera Rhygoplitis, Napamus, Apanteles and Dolichogenidea is poor. Phylogenetic relationships among microgastrine genera have so far proved largely intractable both using morphology or molecular methods (or a combination of both), possibly a result of rapid ancient radiation (Banks & Whitfield 2006; Whitfield & Kjer 2008; Whitfield et al. 2018). Analyses of phylogenetic relationships of microgastrine wasps either did not include species of Illidops (Mardulyn & Whitfield 1999; Whitfield et al. 2002; Banks & Whitfield 2006) or had very limited sampling of Illidops and closely related genera (Abdoli et al. 2024). All species treated here are part of a taxon that Fernandez-Triana et al. (2020) considered the Apanteles group, an informal grouping of 26 genera that includes most, but not all of the Apantelini + Microgastrini tribes sensu Mason (1981). This Apanteles group is characterized by having mostly setose and relatively long ovipositor sheaths and the hypopygium with the ventral margin flexible and pleated. Within the Apanteles group, Illidops is part of a larger subgroup defined by the lack of a closed fore wing areolet. The genus Illidops was erected by Mason (1981) with I. butalidis (Marshall, 1889) as the type species of the genus. Mason’s concept of Illidops upon description of the genus included three described species: A. butalidis (the type), A. szaboi Papp, 1972 (currently a junior synonym of I. mutabilis (Telenga, 1955)), and A. urgo Nixon, 1965. He based his concept on Nixon’s concept of his butalidis -group; however, he did not include a large number of the species which Nixon (1965) previously had included: A. dion Nixon, 1965 (now a junior synonym of I. suevus (Reinhard, 1880)), A. electilis (Tobias, 1964), A. sophrosine (Nixon, 1976), A. contortus Tobias, 1964 (now a junior synonym of I. naso (Marshall, 1885)), A. cloelia (Nixon, 1965), and A. evander Nixon, 1965 (now a junior synonym of I. naso). This discrepancy may be explained by the limited access that Mason may have had to types and other specimens from the Palearctic, which is lamented by Tobias & Kotenko (1986), who did not accept his subdivision of Apanteles in their key. Papp (1988) later integrated more Palearctic species into Illidops by adding species which he and Nixon had previously included in their butalidis - (Nixon 1965, 1976; Papp 1981), suevus - (Papp 1984) and vipio (Papp 1981) groups. Papp himself describes his homologization of European species groups with Mason’s genera as a first step “bearing the errors and misunderstandings of a first endeavour” (Papp 1988: 146). Fernandez-Triana et al. (2014b) provided an updated diagnosis for the genus, first including the character of the “band of rugosity centrally on the posterior edge of the scutellar disc”, which was more or less repeated by Fernandez-Triana et al. (2020). Two species were subsequently transferred to other genera, but most of the species remain in Illidops. Apanteles biroicus Papp, 1973 was transferred back to Apanteles by Fernandez-Triana et al. (2020), and Napamus vipio (Reinhard, 1880) became the type of the genus Napamus, described by Papp (1993). The characters defining the genus were re-examined by Fernandez-Triana et al. (2014b) who noted that the lower margin of the eyes converging and metasomal terga 3–7 weakly sclerotized were absent in several species; they proposed a modified definition of Illidops that focused on the “band of rugosity centrally on the posterior edge of the scutellar disc”, shortened fore wing vein R1 and propodeum fully sculptured but without areola (instead, with a series of short carinae medially on the posterior 0.2–0.3 of the propodeum near the nucha). The previous definitions by Mason (1981) and Fernandez-Triana et al. (2014b) were more or less repeated and combined in the world checklist of microgastrine wasps (Fernandez-Triana et al. 2020: 39). For the present study, we had access to many additional specimens and species, including types and photos of types of several species which had neither been studied by Mason nor by Fernandez-Triana. Our study of those specimens suggests that the definition of Illidops is more complicated than anticipated, even if only restricted to Holarctic species. The main challenge was that we found more variation in the sculptured area interrupting the posterior smooth band of the scutellum centrally than described by previous authors and some species lacking it completely or almost completely. The degree of convergence of the lower margins of the eyes also varies amongst species of Illidops and in some the eyes do not converge. Both characters and their shortcomings are detailed more in a separate section below. Some species of Illidops are hence difficult to clearly place as they combine a set of features characteristic of other genera, e.g., Dolichogenidea (cosmopolitan), Rhygoplitis (NEA, NEO), and Napamus (PAL). The separation of these four genera can be challenging for some species. Table 1 provides a comparison between these genera. Napamus (a genus currently with only two described species) lacks most of the key characters present in Illidops and the two genera should almost always be easily distinguished (Ghafouri Moghaddam et al. 2021). Rhygoplitis has some features that resemble some species of Illidops, e.g., fore wing R1 short, sculptured area interrupting the posterior smooth band of the scutellum centrally, and propodeum coarsely sculptured and with a median, longitudinal carina (Mason 1981; Whitfield 1997). Additionally, the few DNA barcodes available for Rhygoplitis tend to cluster with sequences of Illidops in NJ analyses. Rhygoplitis has rather strongly defined notauli and the overall body sculpture very coarse; it is also a genus so far only known from the Neotropics and the Nearctic (mostly southern areas). The vast majority of species of Dolichogenidea can easily be distinguished from Illidops because all of its species have an entirely smooth band posterior to the scutellum; also the propodeum is very rarely strongly sculptured and, when sculptured, usually not in the common patterns found in Illidops. These two genera usually cluster far apart in NJ topologies of Microgastrinae (e.g., Smith et al. 2013), although the definition of Dolichogenidea is far from resolved (see Mason 1981; Fernandez-Triana et al. 2014b; 2020). However, a few species of Illidops that we have examined as part of this study have a very weak (sometimes almost absent) sculptured area interrupting the posterior smooth band of the scutellum centrally, and in those species the propodeum is also not strongly sculptured (it is either entirely to mostly smooth or at least smooth on the anterior half of the propodeum). Those few species strongly resemble Dolichogenidea – although their sequences still tend to cluster with more ‘typical’ Illidops in NJ analyses. Nevertheless, these species with an almost entirely smooth band posterior to the scutellum and smooth propodeum challenge the concept of Illidops and it may be found in the future that they are better placed in a different genus. This concerns especially I. bellicosus (Papp, 1977) and I. perseveratus (Papp, 1977). Illidops suevu s also has the posterior band of the scutellum almost entirely smooth but has a strongly sculptured propodeum. For this paper we decided to include them in Illidops based on the short vein R1, elongate mouthparts and (in the case of I. suevus) the clustering of their sequences. Shortcomings of some characters used for the identification of Illidops Mason, 1981 Area of rugosity posterior to the scutellum The character “posteriomedian band of rugosity” refers to an area of rugosity posterior to the smooth, at most punctate scutellum and was introduced for Illidops by Fernandez-Triana et al. (2020). Nixon refers to this as “posterior polished band of scutellum interrupted at middle by small patch of rugosity” (Nixon 1976: 709). After examining many species of Illidops, we prefer to refer to this as “posterior smooth band of the scutellum more or less interrupted centrally by sculptured area”. This may range from a clearly visible area of rugosity centrally po

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