World Cynipoidea (Hymenoptera): A Key to Higher-Level Groups

Abstract While much has been learned regarding the phylogeny and evolution of cynipoid wasps, clearly illustrated diagnostic tools and identification keys have remained stagnant. So too, where keys do exist, they are often to genus or species, and there are no user-friendly keys to groups such as tribes, subfamilies, or families.This state of affairs leaves a knowledge gap for non-specialists and slows future research on the group.To address this, we provide a fully illustrated key to the higher-level groups of world Cynipoidea. We also provide summaries of all higher-level taxa with updated generic lists, biological data, distribution, and literature resources. The dichotomous key presented here is complimented with a multi-entry matrix-based key, created in Lucid, and served on www.waspweb.org with online versions of the dichotomous keys also available.

The systematic overview following the key gives a general introduction to each group, especially in terms of diversity, geographical distribution, and biology. Diagnostic characters are usually not repeated in this section, but certain morphological key factors in evolution are highlighted. We list the most relevant literature, and the included genera in each group. The genera are ordered into any valid family-level taxa, the authorship of which are given (and in a few cases in informal groups of genera). For genera, authorship, species number, and geographical distributions are given. Geographical distributions are summarized in text or by abbreviations of biogeographic regions; AT for Afrotropical, AU for Australasian or Oceanic, NA for Nearctic, NT for Neotropical, OR for Oriental, PA for Palearctic (often divided into wPA and ePA for western and eastern Palearctic).
There is no single up to date, authoritative catalog for Cynipoidea. The closest to an updated online resource is Hymenoptera Online (https://hol.osu.edu/), which contains JL's personal cynipid catalog started in the late 1990s, as well as various other cynipoid taxa added over time. It contains a large number of problematic names, and changes made and taxa described since 2008 have been somewhat haphazardly maintained in HOL, as there is no one cynipoid curator of the data in that database. MF has kept a personal catalog focused mostly on Figitidae. Parts of this catalog have been published over time in smaller regional projects (e.g., Forshage et al. 2013;van Noort et al. 2015). Charipinae have been cataloged by the Barcelona research group (Ferrer-Suay et al. 2012); however, these data are not yet present in HOL. Thus, here we have based classification and species numbers on our own lists, manually keeping track of the additions and subtractions from the last decades, referring back to HOL for comparison but including numerous changes from recent years alerted via Zoological Record and other sources, as well as making certain pragmatic considerations.
There are still a rather large number of mystery names available, linked to lost or missing type specimens. In some cases, it is not clear if a particular name even belongs in Cynipoidea, or rather Chalcidoidea, Diapriidae or dipteran Cecidomyiidae. Further, some genera (e.g., Eucoila, Ganaspis, Trybliographa, Andricus, Dryocosmus) have had a large number of species assigned to them for seemingly arbitrary reasons. Keeping all these difficult circumstances in mind, we have presented species numbers that we have found documentation for and consider meaningful as preliminaries, while these numbers may still differ significantly from actual species numbers. In genera where these numbers are particularly problematic, we have mentioned this specifically, and also to indicate where particularly large number of undescribed species belong, as well as where large numbers of clearly misclassified or insufficiently known species reside. Hopefully, the data here will pinpoint where future research is most needed.
All specimens used here, except for Qwaqwaiini, are housed at the USNM (National Museum of Natural History, Washington, DC) and were often cleaned with a minute paintbrush and mounted to achieve the necessary views for each couplet. Unique specimen identifiers, in the form of USNMENT 'barcode' numbers, link images to specimens housed at the USNM. Images were captured using a Macroscopic Solutions 'microkit' (Tolland, CT) imaging station and stacked using Zerene Stacker LLC (Richland, WA). Please contact MB for additional details of this process.
We suggest the following to get the most out of using this key: 1) high-quality optics are a necessity for observing the pronotal plate and other small features throughout the key; 2) light dispersing film (in the United States, mylar is commonly used) should be installed if using fiber optic light sources with incandescent bulbs (the glare produced by these lights will obscure details of the cuticle). Lastly, having some biological and geographic data will make using the key easier.

Figs. 66 and 67.
-Female antenna with 10 flagellomeres; last flagellomere wider than the penultimate (ant, Fig. 66); male antenna with either F2, F3 or both modified. Ventral area of gena with 5-9 vertical carinae (gen, Fig. 67). Genal carina present. Ventral part of clypeus at most slightly projecting over mandibles. Dorsolateral margin of pronotal plate strongly projecting laterad (pn, Fig. 66 Fig. 68). Hypopygium abrupt, not prolonged into a ventral spine; with a dense tuft of long setae (arrow, Fig. 69 Insect Systematics and Diversity, 2020, Vol. 4, No. 4  12. Metasomal terga 2 + 3 fused, or apparently fused, with or without a suture between terga 2 and 3; metasoma appears as one large segment 14. Pronotal plate present, defined dorsally and ventrally (pt. 15. Mesopleuron with reticulate or rugulose sculpture (msp, Fig. 88). Submedian depressions on pronotal plate effaced, shallow, and indistinct (ad, Fig. 89). Dorsal part of pronotal plate not reaching mesoscutum (pt, Fig. 89). R1 in forewing reaching anterior margin of wing (R1, -Apex of forewing rounded (arrow, Fig. 131). Propodeum variously setose to glabrous, never with densely packed setae (Fig. 132)    This monotypic family is one of the rarest within the Hymenoptera. Austrocynips mirabilis Riek, 1971 was reared from cones of hoop pine (Auracaria cunninghami Aiton ex D. Don) in Australia that were infested with oecophorid moths. Previously, cones from these trees were collected for propagation and timber production; this is now achieved through other means, and cones are not regularly collected. As these cones are difficult to access, Austrocynips has not been collected again since the original description. Riek (1971) reports that other species of Araucaria were also surveyed but yielded no Austrocynips.

Ibaliidae
Figs. 181-183 Ibaliids are generally a holarctic group with the highest species richness in North America (Liu and Nordlander 1992). These are very distinct cynipoids, often brightly colored, and several times larger in body size than any other cynipoids (some liopterids are also large). Ronquist (1995a,b) hypothesized that this group, along with liopterids and Austrocynips, composing the 'macrocynipoids', represent the most pleisiomorphic forms of cynipoids, and further suggesting that the ground-plan biology for cynipoids is parasitizing wood boring insect larvae. This argument is supported by the fact that all members of macrocynipoid families possess horizontally strigate mesoscuta, putatively an adaptation to chewing out of woody substrates where their hosts dwell. Indeed, ibaliids are known to be koinobiont endoparasitoids of siricid woodwasps (Hymenoptera: Siricidae) (Hurley et al. 2020). Species of Ibalia are typically not very rare in the eastern Nearctic Region and parts of the Palearctic Region; species in the desert southwest of the United States are more rarely encountered. Species of Heteribalia are not common in the wild, but one species is regularly intercepted from wood products entering the United States from China (Buffington, personal observation). Eileenella has not been collected since its description. Eileenella has been placed in its own monotypic subfamily Eileneellinae Kovalev, 1994, which appears not to have been formally synonymized in the literature, even though its usefulness is obviously limited and has not been commonly cited.
Distribution. Holarctic and Oriental, one genus extends into Papua New Guinea; Introduced to Australia, New Zealand, and South Africa for biological control (Hurley et al. 2020).
Relevant literature. Ronquist and Nordlander (1989) provided an exhaustive study of the morphology of Ibalia rufipes that remains the basis of all morphological studies among cynipoids; Liu and Nordlander 1994, revision;Nordlander et al. 1996, phylogeny;Ronquist 1999 As with the ibaliids, most members of this family are rather striking in appearance, often to be found outside the cynipoids in museum collections of Hymenoptera. Some are brightly colored, though most species have a dark, black, and shiny appearance. As mentioned elsewhere, liopterids are among the macrocynipoids: large in size, with horizontally strigate mesoscuta. There are no definitive host records, only anecdotal evidence that they are parasitoids of wood-boring insect larvae (Ronquist 1995a. Four subfamilies are recognized, and species/genera have been often been classified in Cynipidae and other groups. Liopterids are found worldwide except the western Palearctic Region; most species are found in the tropics and subtropics. Paramblynotus is the most speciose of all liopterid genera, with an incredible diversity of species in southeast Asia. Most liopterids are rarely encountered in the field, though Paramblynotus can be very abundant in Malaise traps during certain times of the year.
Biology. Associated with wood; presumably parasitoids of woodboring insect larvae.
Distribution. Worldwide except western Palearctic Region. Of the subfamilies, Mayrellinae has the same distribution as the entire family, whereas the other are more restricted: Dallatorrellinae: Paleotropical; Oberthuerellinae: Afrotropical; Liopterinae: Neotropical. Relevant literature. Hedicke and Kerrich (1940) and Ronquist (1995a) revised the family.  revised Paramblynotus.  revised the Oberthuerellinae; van Noort and Buffington (2013) revised Afrotropical Mayrellinae. Ronquist (1995a) provides a complete overview of the family, keys all the genera, and provides a world catalog.

Cynipidae: Cynipinae
Note: Most commonly in recent years, authorship of family-group names based on Cynips has been quoted from Latreille (1802). However, Alonso-Zarazaga and Nieves-Aldrey (2002) corrected the authorship of the family since Latreille did not include any actual cynipids in his family, and the name was not made available until later, making 'Billberg, 1820' the correct authorship.
The current classification of the Cynipidae places all extant forms in a single subfamily, with the majority of species falling into one of four tribes: the oak gallers (Cynipini), the herb gallers (Aylacini), the rose gallers (Diplolepidini), and the inquilines (Synergini). Ceroptres, previously classified within Synergini, have recently been placed into their own tribe, the Ceroptresini. Diastrophus, gallers on rosaceous herbs, were previously classified within Aylacini, are now in their own tribe, Diastrophini, which includes some inquiline genera. Many herb galling genera, previously classified within Aylacini, have been moved to Aulacideini and Phanacidini. Rarer tribes include the Pediaspidini (maple gallers), and the Eschatocerini (gallers of Acacia and Prosopis in the Fabaceae). Lastly, two additional rare tribes have been recently described based on morphologically divergent forms from the Southern Hemisphere: Qwaqwaiini, including a single gall inducer on Scolopia (Salicaceae) in South Africa, and Paraulacini, including two genera (Paraulax and Cecinothofagus) of inquilines (or possibly parasitoids) in chalcidoid galls on Nothofagus (Nothofagaceae) in southern South America (Chile).
Nieves-Aldrey (2001) provides an overview of the Iberian fauna and provides keys to tribes. Ronquist et al. (2015) established several new tribes and provided an illustrated key. Pujade-Villar (2019) follows the same classification of Ronquist et al. (2015) and provides an alternative identification key. Unlike many other insect groups, cynipids can also be readily identified by the gall left behind after the adult wasp has emerged. Weld (1957Weld ( , 1959Weld ( , 1960a pioneered this form of identification, and summarized what was known about gall morphology and host plant records in series of privately printed pamphlets. In addition, Weld's own collection of galls are located at the USNM and have undergone recuration recently. More recently, Russo (2006) has updated much of Weld's work, and includes not only color images of galls, but also covers other galling insects of North America. Further, Coulianos and Holmåsen (1991) provide an overview of galls in Scandavia.  This recently circumscribed tribe includes many taxa formerly treated in Aylacini, many species of which are treated by Nieves-Aldrey (1994). Members moved to Aulacideini include species that are gallers on Lamiaceae and Asteraceae (Ronquist et al. 2015), but do not include the gallers of Papaveraceae (now Aylacini) or Rosaceae (now Diastrophini).

Aulacideini
Biology. Gall inducers on various herbaceous plants in Asteraceae, Lamiaceae, Valerianaceae, and some Papaveraceae (Ronquist et al. 2015). Aulacidea subterminalis have been used in the biological control of invasive weeds in North America (APHIS 2011) and New Zealand (Syrett et al. 2001).

Classification.
Aulacideini Nieves-Aldrey, Nylander and Ronquist, 2015 (the availability and authorship of this name is disputed and will hopefully be settled soon)  Figs. 193-195 Ronquist (1994) argued that this tribe, as it was circumscribed, was not monophyletic, and formed the basal lineages of Cynipidae. Following this, Liljeblad and Ronquist (1998) presented more robust data to support splitting up Aylacini, but no action was taken until Ronquist et al. (2015). We now recognize this tribe as being restricted to species galling Papaver in the Palearctic region. Several taxa previously classified in this tribe can now be found in Aulacideini, Phanacidini, and Diastrophini. These taxa all shared the trait of being gallers of herbs and other non-woody plants; Ronquist et al. (2015) concluded that these are unrelated host shifts.

Aylacini
Biology. Gall inducers on Papaver in the Palearctic Region.
Distribution. Palearctic Region. Occasionally intercepted on plants being imported to North America; possibly introduced into other regions (Buffington, personal observation).

Classification.
Aylacini Ashmead, 1903 Aylax Hartig, 1840; 20 species PA, introduced NA Barbotinia Nieves-Aldrey, 1994; 1 species wPA Iraella Nieves-Aldrey, 1994; 3 species wPA Ceroptresini  This very small tribe was erected as the species contained here render Synergus paraphyletic. As a result of the topology recovered in Ronquist et al. (2015), Ceroptres was moved to the novel tribe Ceroptresini. generic diversity is relatively high and little work has been done on the Cynipini fauna until recently (e.g., Tang et al. 2009;Ide et al. 2010;Tang et al. 2011;Melika et al. 2011;Ide et al. 2012;Melika et al. 2013b;Ide and Abe 2015;Tang et al. 2016). New genera and new species have also been continuously discovered in the Nearctic and Neotropics (e.g., Medianero and Nieves-Aldrey 2011; Nieves-Aldrey et al. 2012;Pujade-Villar et al. 2012a, b;Pujade-Villar et al. 2013;Medianero and Nieves-Aldrey 2013), highlighting the fact that the taxonomy of Cynipini is still far from complete. Taxonomy of Cynipini has been controversial, including several species previously classified in Andricus and Callirhytis having been moved between these two genera (Burks 1979), and several Nearctic Callirhytis species transferred to newly erected genera Kinseyella Biology. The life cycle of Cynipini involves cyclical parthenogenesis (heterogony), with a sexual generation where males and females mate to produce an asexual generation of only females, that reproduce parthenogenetically and gives rise to a new bisexual generation. The two generations differ in terms of the gall phenology, galling positions, gall structure, and adult morphology and size. These biological distinctions have been led the two generations of the same species classified as different species and even as different genera in the past. Two Palaearctic genera, Andricus and Callirhytis, are host alternators (heteroecy) that their life cycles alternate between two host-plant subgroups, section Cerris and section Quercus sensu stricto in the genus Quercus. Although in some species, the two alternating generations have been associated, for many species they have not yet been matched. Field observation is a firm approach to associate the two generations, however, DNA barcoding is another useful tool to pair the two generations (e.g., Ács et al. 2007, Melika et al. 2013a). There are only three exceptions in Cynipini known to reproduce purely parthenogenetically. The first case is the global pest, the chestnut gallwasp Dryocosmus kuriphilus Yasumatsu (Aebi et al. 2006). This species has one generation per year and has been introduced into Europe, North America, and some countries in Asia outside its native region in China. The other two species, Andricus targionii Kieffer and A. pseudoflos (Monzen), from Japan, Korea, China and Far East of Russia, are derived from their cyclically parthenogenetic ancestors A. mukaigawae (Mukaigawa) and A. kashiwaphilus Abe through the deletion of sexual generation (Abe 2007). Oak gallwasps have been very conservative on their host-plant choices, and host switches were extremely rare in the evolution of oak gallwasps   (Weld 1952). Stone et al. (2002) and Csóka et al. (2005) reviewed the general biology, ecology, and evolution of Cynipini, and Abe et al. (2007) reviewed species richness, host-plant diversity, and background on the hypotheses of geographic origin of Cynipini. The Western Palaearctic fauna of Cynipini is reviewed in Melika (2006) Ronquist et al. (2015), contains the gallers Diastrophus and Xestophanes, formerly included in the tribe Aylacini, and the inquilines Periclistus and Synophromorpha, formerly included in the Synergini. Both the gallers and the inquilines are associated with host plants in the family Rosaceae. With respect to the inquilines, this appears to be a case of agastoparasitism, where the inquiline of a gall inducer is a close relative. Hence, including these inquilines in Synergini rendered that tribe paraphyletic.
Distribution. Holarctic, transgressing into the Neotropics. Ronquist et al. (2015). Ronquist (1994) first investigated the group phylogenetically and recognized the Aylacini where these genera previously were classified) as paraphyletic. Ritchie and Shorthouse (1987)  The wide variety of galls produced by these species, and the relative ease of locating them in the field, has led to a rather extensive literature on the biology and ecology of these wasps. A very thorough review by Shorthouse (1993) describes in detail the research on the diplolepidine wasps, including gall induction, larval feeding, life cycle aspects, and parasitoids. As hybridzation among rose species can be common, confusing the taxonomy of the group, rose gallers seem to have adapted to intermediate species, much in the same way oak gallers in the Cynipini seem to have 'specialized' on intermediate oak species.

Relevant literature. Tribe is circumscribed and diagnosed in
Morphologically, these wasps all share a rather unique hypopygium that extends ventrally, and has been described as 'plough-share shaped' in literature. Phylogenetically, Liljeblad and Ronquist (1998)  low support. More recently, Ronquist et al. (2015) found the group sister to Pediaspini and Eschatocerini.
Distribution. Holarctic. Could be moved into non-native areas with horticultural products.

Figs. 211-213
This monotypic tribe may feel unsatisfactory for taxonomy, but its erection is based on phylogeny (Ronquist et al. 2015). This unusual group can be readily collected when host plants are located; otherwise, the taxon is rarely collected.
Biology. Species are gall inducers on Prosopis spp. and Acacia spp. (Fabaceae) in South America.
Distribution. Arid regions of the Neotropics.
Relevant literature. Nieves-Aldrey and San Blas (2015) revised the tribe and described the biology in depth; Ronquist (1995b) and Ronquist et al. (2015) studied the phylogenetic placement of the group.

Figs. 217 and 218
The name has been rendered alternately as Pediaspini and Pediaspidini in literature. Pediaspidini is the linguistically correct, and there is no prevailing usage that speaks for the other option. This tribe of Palearctic species gall Acer spp. Himalocynips (biology unknown) was originally described in its own family (Yoshimoto 1970).
Relevant literature. Ronquist (1995b) suggested the inclusion of Himalocynips within Pediaspidini, and has been followed since.
Biology. Mostly stem gall inducers on Asteraceae, with a few species on Lamiaceae and Apiaceae.
Distribution. Palearctic Region, most species in arid Southwest & Central Asia. Phanacis recorded from Kenya presumably introduced; intentionally introduced into Australia and South Africa for weed biological control.
Relevant literature. Ronquist et al. (2015) is the most recent treatment of the group; Ronquist (1995bRonquist ( , 1999 discusses issues with the placement of genera now found in this tribe.

Figs. 227-232
The traditional composition of this tribe turned out to be polyphyletic, and included any cynipid that was known or presumed to be an inquiline. However, Ronquist et al. (2015) demonstrated that inquilinism has evolved numerous times, and as a result, some members of Synergini s.l. were moved to other tribes (see Ceroptresini, Diastrophini, above). Synergus is readily identified by the presence of a syntergum on the metasoma, and is by far the most readily collected and speciose genus in the tribe. closely allied to S. itoensis from Japan, which lead to Ide et al. (2018) arguing that the Synergini gall inducers have independently arisen from other inquilines. Rhoophilus is wholly unique being an inquiline forming secondary cells in galls induced by Scyrotis moths (Cecidosidae) on Searsia (formerly Rhus) (Anacardiaceae) shrubs and trees. Larval cells expand into the hollow interior of the host gall resulting in death of the gall-inducing moth larva ).
Distribution. Mostly Holarctic, but single taxa present in all regions; Rhoophilus endemic to South Africa.

Figitidae
This family is the most speciose group within the Cynipoidea. Members of this family are, when biology is known, internal parasitoids of other holometabolan insects, and in at least one group, hyperparasitoids.  reviewed all the host records of the family and summarized the reliable host records. With some 157 genera and more than 1,700 species, subfamilies and tribes have been erected to bring some order to this diversity. In fact, it is typically easier to identify the lower groups of Figitidae than the family itself, and this is reflected in the key here. In terms of biology, the subfamilies fall into three categories: some are parasitoids of muscomorphan Diptera (Eucoilinae, Figitinae); some are inquilines or parasitoids inside galls (Euceroptrinae, Mikeiinae, Parnipinae, Plectocynipinae, Thrasorinae: all species-poor); some are parasitoids of various insects attacking aphids (Anacharitinae, Aspicerinae, Charipinae). Finally, hosts are unknown for Emargininae and Pycnostigminae.

Figs. 233-236
The moderately diverse anacharitines are often among the more easily recognizable wasps within the cynipoids. They tend to be elongate, with a subtriangular head (in anterior view). In fact, the head is frequently the widest part of the animal (when viewed dorsally. The narrow petiole, so characteristic of the common Anacharis, in conjunction with a very short ovipositor, is hypothesized to be an adaptation for 'quick strike' oviposition into predatory Neuroptera (Buffington 2007). The narrow petiole allows for maximum flexibility in directing the ovipositor tip; the short ovipositor requires the slightest insertion into the larval body to deposit an egg. Together, this allows the wasp to successfully oviposit before the host can mount a counter-attack. The limits of some genera are poorly circumscribed.
Distribution. Main genera are widespread but mostly Holarctic, while the Neotropical region has several endemic genera and the Afrotropics one (Acanthaegilopsis). Anacharis is the most widespread with at least one species common in Australia. reviewed the Afrotropical species of the subfamily.  provided phylogenetic data on the group. Classification.

Figs. 237-242
With respect to general morphology, Aspicerinae are among the most spectacular of all figitids. They are typically stout with very little in the way of sexual dimorphism. While a majority of figitids are shiny black, several species of Aspicera, Callaspidia and Anacharoides are bright orange to red in color. Their wings are glabrous and shimmer in the right light. Several genera, including Aspicera, Prosaspicera, and Paraspicera have well-developed scutellar spines. Most aspicerines have stout hind legs and an extremely petiolate metasoma. Like the anacharitines, aspicerines are quick-strike parasitoids, attacking syrphid larva that themselves provide a significant threat to the wasp during oviposition.
A very short ovipositor, coupled with a highly flexible metasoma and strong hind legs, allow the wasp to attack the host before the host can mount a counter attack (Buffington 2007). Melanips is taxonomically problematic with respect to Figitinae and Aspicerinae. Melanips lacks morphological characters that can positively associate the genus with either subfamily; however, species of Melanips have been reared from Chamaemyiidae larvae predating on aphids, and this biology coincides with Aspicerinae. Further,  recovered Melanips as sister-group to the remaining Aspicerinae, and suggested moving Melanips to that subfamily. The group is currently being evaluated as its own subfamily (Mata-Casanova et al. personal communication). Despite recent revisions, several species remain undescribed and some regional faunas largely unexplored. This is an extremely diverse group known exclusively as hyperparasitoids in aphid and psyllid systems. While not particularly diverse at the genus level, the species diversity in Alloxysta is remarkable, and it is possible numerous cryptic species complexes are present in the genus. The small size and smooth cuticle of charipines make them easily recognized at the subfamily level. While genera are relatively approachable with respect to identification, species limits are still being addressed, and in some cases, species-level identification is difficult if not impossible. The research group at the University of Barcelona (Pujade-Villar Lab) is the most active in the world and has produced the most recent research on the group, spearheaded by Mar Ferrer-Suay. The volume of papers and new taxa in recent years is remarkable, and has been particularly valuable in making the types accessible. Up to a point, nomenclatural issues, as well as distribution knowledge and practical identification have benefitted significantly from this. But this is not definitive since species circumscriptions are still often uncertain, as revisions have usually been made on the basis of rather small numbers of specimens and a set of preferred morphological characters, not considering biological or molecular evidence nor phylogenetic considerations. Particularly troublesome was the erection of all wingless forms into separate species.
Distribution. Worldwide, but with the largest number of species in the Holarctic, while two unusual groups (Dilapothor and Thoreauana) are from Australia.
Relevant literature. Menke and Evenhuis (1991)  This unusual group of diminutive wasps has been variously classified, often as eucoilines. Ronquist (1999) clarified the circumscription of the group and recognized them as their own subfamily (reviewed by Pujade-Villar 2019). While typically rare in most parts of the world, they are a dominant figitid group in Madagascar . Several genera have been described, but all have been synonymized under Thoreauella Girault; considering that, nothing less than a world-wide revision would be able to find phylogenetically meaningful groups.
Biology. Host unknown, but adults have been collected from formicid refuse piles (Weld 1960b).
Distribution. Pantropical and transgressing into Eastern Palearctic, but rarely collected outside Madagascar.
Relevant literature. Ronquist (1999) circumscribed the group; Weld (1960b) suggested species are ant associates. Van Noort et al. (2015) reviewed the Afrotropical species and moved all species into Thoreauella.

Figs. 251 and 252
This small group has been variously classified, most frequently as cynipids. Species are gall associates, presumably gall wasp parasitoids. Ronquist (1999) grouped them as members of the 'figitoid inquilines', but Buffington and Liljeblad (2008) revised the genus and recognized the group as a distinct subfamily;  phylogenetically recovered the group outside of the other gall-associated figitids.

Classification.
Euceroptrinae Buffington and Liljeblad, 2008 Euceroptres Ashmead, 1896; 4 species NA Plate 19. Emargininae. Fig. 249, Thoreauella sp., USNMENT01022106. Fig. 250 Eucoilinae  Within the Figitidae, the vast majority of both species diversity, and abundance, occurs within Eucoilinae. Eucoilines can be collected very easily on all continents (they are even found on Antarctic islands), and many species do very well in the suburban to urban environments, as well as around farms. Unlike most other cynipoids, the eucoilines are immediately recognizable by a single morphological feature: the scutellar plate. This feature is a structure holding up a glandular release pit the function of which is currently unknown. The feature is often referred to as a cup, a plate, a teardrop, or a disk. Because of their commonness, and being immediately recognizable from all other cynipoids, many species have been more or less haphazardly described. As a result, this large group became an impenetrable taxonomic morass for decades until Nordlander's work in the late 70s and early 80s began to make some sense of the diversity. Nordlander (1982b) summarized his work and generated generic groups that remained relevant well into the 2000s. Fontal-Cazalla et al. (2002) ignited renewed interest in the phylogeny of the group, and set the stage for an expanded analysis at the core of . The resulting phylogenies and recognition of phylogenetically informative characters have helped motivate addressing the taxonomy of larger Plate 21. Eucoilinae. Fig. 253, Ganaspis brasiliensis (Ihering, 1905), USNMENT01520001. Fig. 254, Odonteucoila sp., USNMENT01231882. Fig. 255, Kleidotoma sp., USNMENT01525865. Fig. 256, Gronotoma sp., USNMENT01231843. Fig. 257, Trybliographa melanoptera, USNMENT01231838. Fig. 258, Striatovertex sp., USNMENT01231830.
groups of eucoilines, including the Diglyphosematini (Buffington 2011), Zaeucoilini (Buffington 2009) and Eucoilini (Forshage 2009). The most comprehensive regional treatment of the Eucoilinae was published by van Noort et al. (2015) and establishes a format for future projects on eucoilines at other regional scales. In order to make sense of the genera within the group, tribes have recently been established. However, this is very much a work in progress and many genera currently lack tribal placement.
In all regions, the majority of species remain undescribed, and the described species are very often in completely wrong genera (due to the mentioned earlier lack of knowledge of phylogenetically informative characters). The latter problem (but not the former) has been addressed and largely rectified for some regions (Europe, North America, the Afrotropics) but remains at large elsewhere (the Oriental, Oceanic, and Neotropical regions all have a majority of described species still misplaced).
Eucoilines are parasitoids of cyclorraphous flies , with most host associations still unknown but spanning over a wide diversity of flies (Ronquist 1999, Buffington 2007. Drosophila parasitoids in the genera Ganaspis and Leptopilina have been used in lab studies since the 1960s. Their biology has thus been studied in remarkable detail, and they are currently being considered for use in the biocontrol of Drosophila suzukii ("SWD"). Other eucoilines that have been used in the biological control of pest flies include: Aganaspis species on tephritids; Trybliographa species on onion maggot; Banacuniculus; and Ganaspidium species on leafminers.
Biology. Koinobiont endoparasitoids of cyclorrhaphous flies. Early instar maggots are parasitized; and then after the host fly forms a puparium, the wasp kills the host, and completes its own pupation within the host puparium. Abe (2009) documented Gronotoma micromorpha as an egg-larval parasitoid of Liriomyza trifolii; it is not know how widespread this type of biology is among Eucoilinae. Hosts are unknown for most species, and the records we have are very often anecdotal, but several preliminary patterns can be observed. First, that almost all reliable host records are indeed of muscomorphan (cyclorrhaphous) flies; some exceptional records of Kleidotoma on Sciaridae appears to us to be correct, whereas numerous, unisolated host records from Mycetophilidae are probably all erroneous. Second, that probably at least half of the Eucoilinae species attack saprophagous flies in more or less ephemeral habitats (dung, carrion, compost, debris, fermenting fruit and mushrooms) whereas another good portion attack phytophagous flies (leaf miners etc.). Thus, Diglyphosematini and Zaeucoilini are mostly but not exclusively on leafmining Agromyzidae, while Kleidotomini and Eucoilini are mostly but not exclusively on various saprophagous flies. Third, a "rule of thumb" that has been used among workers in the group for decades is to expect any genus of Eucoiline wasp to attack one particular family of flies. This is not valid in any strict sense but a mere pragmatic guidance, but with our limited data it works in a large number of cases. Large eucoiline genera tend to include exceptions (host switches), and two large genera (Kleidotoma and Hexacola) are known to have a wide range of hosts. The fly families attracting the largest number of eucoiline genera are Drosophilidae and Agromyzidae. Very little is known about host specificity of individual eucoiline species.
Distribution. Worldwide. Particularly speciose in the Neotropical Region.
Relevant literature. Weld (1952) remained dominant until the publications of Nordlander established a new standard of thoroughness and phylogenetic thinking in eucoiline research (Nordlander, 1976, 1980, 1981, 1982a, summarized in Nordlander [1982b). Van Lenteran et al. (1998) and van Alphen et al. (1991) investigated biology and host use. Forshage and Nordlander (2008) provided basic circumscription of tribes and keyed western Palearctic genera, Buffington revised Diglyphosematini (Buffington 2011) and the new tribe Zaeucoilini (Buffington 2009). Forshage (2009) summarized global overview of the subfamily and especially Eucoilini. Van Noort et al. (2015) provided a substantial overview of the Afrotropical fauna, and Forshage et al. (2013) cataloged Nearctic taxa. A combination of the Afrotropical key and the European key Forshage andNordlander 2008) will allow generic recognition of most Eucoilinae worldwide, except in the utterly diverse Neotropics (cf Buffington et al. 2006) and highly aberrant Pacific islands (cf Beardsley 1989). Species-level identification is very often not possible, but many common European species can still be keyed with Quinlan (1978) even though taxonomy is obsolete, and odd taxa globally can be recognized using Weld (1952). Useful generic treatments are available for Ganaspidium (Buffington 2010a), Banacuniculus (Buffington 2010b), Zaeucoila (Buffington et al. 2018), European Rhoptromeris (Nordlander 1978, Costa Baião and, Leptopilina in different regions (Nordlander 1980, Allemand et al. 2002, Novkovic et al. 2011, Lue et al. 2016, and several genera in Taiwan (Lin 1987(Lin , 1988, as well as for several lesser, recently described genera or regional assemblies thereof, while many recent studies still await publication. Fontal-Cazalla et al. (2002) and    Weld, 1962; 2 species AT Bothrochacis Cameron, 1904; 8 species currently in genus but a few more belong here, mostly AT but also OR and Hawaii Eucoila Westwood, 1833; only 3 described species currently are classified as Eucoila in a meaningful sense, while many need to be removed elsewhere and yet a few others need to be moved in or described as new, PA, NAPA, NA Leptopilina Förster, 1869; 41 described species currently in the genus in a meaningful sense but more are currently being described and still ca 12 need to be moved in from other genera, worldwide Linaspis Lin, 1988; 1 species ePA Linoeucoila Lin, 1988; 11 species, OR but undescribed species also AT Maacynips Yoshimoto, 1963; 3 described species and numerous undescribed in Australia and throughout the Pacific and East Asia Quasimodoana Forshage, Nordlander & Ronquist, 2008; 2 species PA, NA Trybliographa Förster, 1869; 43 described species currently in the genus in a meaningful sense but some 20 more need to be moved in from other genera and far more described as new, worldwide but mainly Holarctic Ganaspini Belizin, 1961 Acantheucoela Ashmead, 1900; 6 species NT Aganaspis Lin, 1987; 7 described species currently in the genus in a meaningful sense but ca 10 more need to be moved in and more described as new; worldwide but mainly Oriental and Neotropic Areaspis Lin, 1988; 2 species but 2 more need to be moved in and additional ones described as new, OR, AT Aspidogyrus Yoshimoto, 1962;4 species Hawaii Caleucoela Kieffer, 1909; 1 species NT Chrestosema Förster, 1869; 3 described species currently in the genus in a meaningful sense but more will soon be moved in, and described as new, while remaining others will be moved out; mainly OR, PA Coneucoela Kieffer, 1909; 1 species NT Didyctium Riley, 1879; 12 described species currently in the genus in a meaningful sense but ca 10 need to be moved in and many more described as new; worldwide Dieucoila Ashmead, 1903; 7 described species currently in the genus in a meaningful sense but ca 10 need to be moved in and more described as new; NT, NA Discaspis Lin, 1988;1 species OR Ditanyomeria Yoshimoto, 1963;4 nominal species AU, to be synonymized Endecameris Yoshimoto, 1963; currently 2 species but many undescribed, PA, OR, AT, AU Epicoela Borgmeier, 1935; 2 species NT Epochresta Lin, 1988; 1 species OR Euxestophaga Gallardo, 2017; 1 species NT Fontaliella Pujade-Villar, 2013; 1 species NT Ganaspis Förster, 1869; 25 described species currently in the genus in a meaningful sense, but ca. 40 more need to be moved in and yet more described as new; worldwide Gastraspis Lin, 1988; 2 species OR, AT Glauraspidia Thomson, 1862; 3 described species currently in the genus in a meaningful sense, but a few more are being moved in or described as new; PA, rare in NA, NT Hexacola Förster, 1869; 43 described species currently in the genus in a meaningful sense but ca 25 more need to be moved in and many more described as new; worldwide Humboldteria Buffington 2017; 4 species NT Hydrelliaeucoila Díaz & Gallardo, 2009; 1 species NT Hypodiranchis Ashmead, 1901; 9 described species currently in the genus in a meaningful sense but a few more need to be moved in or described as new: Pacific and East Asian Lispothyreus Yoshimoto, 1962;2 species Hawaii Mirandicola Belizin, 1968; 8 described species currently in the genus in a meaningful sense but some more are currently being described and many remain undescribed, OR, PA Nesodiranchis Perkins, 1910; 6 species Hawaii Nordlandiella Díaz, 1982; 2 species but 3 more need to be moved in and some described as new; NT, NA Odonteucoila Ashmead, 1903;8 species NT Odontosema Kieffer, 1909; 1 species NT Paraganaspis Díaz & Gallardo, 1996; 2 species but 6 more need to be moved in and some described as new; NT, NA Pentamerocera Ashmead, 1896; 1 species but very poorly known; NT Perischus Weld, 1931; 2 species NT Promiomera Ashmead, 1903 gall wasps, but also not recognizably eucoilines, anacharitines, or aspicerines, have been placed here. Hence, Figitinae has been a classic 'dustbin' concept. The phylogenetic research started by Ronquist (1999), and carried on by , recovered a core group of 'obvious' figitine genera (vis. Neralsia, Xyalophora, Figites), demonstrating that at least at a basic level, the group may be monophyletic. These core genera are some of the largest of all species of figitids, and are typically glabrous except for some stout setae, also having glabrous wings (apparently an adaptation to their often sticky host habitats, i.e., dung and carcasses). More peripheral genera, such as Melanips and Lonchidia, have been much more difficult to confine to Figitinae; this is reflected in this very paper, where these two taxa come out at the end of the figitid key to groups. Some figitines can be quite common, especially in Malaise traps and in sweepnet samples of pastureland.
Biology. Figitinae are parasitoids of muscomorphan Diptera, but for most taxa there are no known host associations. The available records show a similar pattern as in Eucoilinae, a dominance for attacking saprophagous flies in ephemeral habitats (dung, carrion, compost), but several attacking phytophagous flies. The speciesrich and more common genera are all focused on large, quickdeveloping calyptrate flies, while some notable forms parasitize, i.e., Anthomyiidae in conifer cones. While they have been included in surveys for natural enemies of species such as horn fly and face fly (Muscidae) in the United States, the parasitism rate has been too low for actual impact. Similarly, in Europe and Asia, Amphithectus (under very varying names) have been studied searching for natural enemies of cone seed predators, but no practical application has been developed.
Distribution. Worldwide. Some species of Neralsia and Xyalophora move with muscoid flies associated with livestock.  (2008a, 2008b, 2008c) North American Neralsia. Forshage and Nordlander (2018) clarified the circumscription and biology of the Amphithectus group.    (2008) This monotypic subfamily has been the focus of a great deal of research on the evolution of Figitidae and Cynipidae. Originally classified as a cynipid, Parnips was later elevated to its own subfamily of Figitidae, and has been hypothesized as being the sister-group to the rest of Figitidae (Ronquist and Nieves-Aldrey 2001;). This unusual genus are parastoids of gall wasps (Aylacini) in Papaver (Papaveraceae) flowers in the Mediterranean. While usually rare in collections, Parnips can be readily obtained from Barbotiniainfested Papaver flowers.
Biology. Primary parasitoid of Aylacine gall wasps in Papaver.

Figs. 269-273
This is another small group of gall-associated Figitidae that were considered members of the informal 'figitoid inquiline' group of Ronquist (1994;1999). Ros-Farré and Pujade-Villar (2007)  The majority of genera that have been previously treated by Ronquist (1994Ronquist ( , 1999 as 'figitoid inquilines' are now members of this small subfamily. All members of this group are associated with galls; however, the species are from various regions, and in some cases, details of their biology is unknown. In most cases, very few specimens of these species are in collections. The outlier here is Myrtopsen, which can readily be reared from tanaostigmatids on Fabaceae in the Nearctic and Neotropical Regions. Phylogenetically, the group is relatively plesiomorphic within Figitidae and forms a grade along with Euceroptrinae and Plectocynipinae ).
Biology. In most cases, unknown but presumably associated with galls. Myrtopsen is a primary parasitoid of Tanaostigmatidae (Chalcidoidea) on Malvaceae and Fabaceae   Ronquist (1999) discussed the so-called figitoid inquilines.  investigated the phylogeny of the group. Classification.