Cynipoidea, Latreille, 1802

Buffington, Matthew L., Forshage, Mattias, Liljeblad, Johan, Tang, Chang-Ti & Noort, Simon van, 2020, World Cynipoidea (Hymenoptera): A Key to Higher- Level Groups, Insect Systematics and Diversity 4 (4), No. 1, pp. 1-69 : 1-32

Cynipoidea

The skeleton of this key was devised by MB, MF, and JL while teaching The Hym Course in Tovetorp, Sweden, in 2012; later drafts were updated with student feedback from each subsequent Hym Course offering. Some key characters are modifications of the Hymenoptera of the World key ( Goulet and Huber 1993). Additional characters and character state definitions presented here follow Ronquist et al. (2015) and van Noort et al. (2015). All morphological terms follow those used in Hymenoptera of the World ( Goulet and Huber 1993) and are further defined on the Hymenoptera Anatomy Ontology project (http://portal.hymao.org/ projects/32/public/ontology/). No new terminology is introduced here. Reviewers of earlier drafts of this paper helped in clarifying problematic characters and definitions. The key is illustrated using color photomicrographs of museum specimens. We are hoping this brings the user closer to the reality of working with specimens. For those interested in using a multi-entry matrix key, www.waspweb.org hosts the Lucid version of this key.

The key covers all Cynipoidea worldwide, and some of these groups are only found in certain areas or on certain plants. Some rarer taxa that may not be routinely collected worldwide include Austrocynipidae , Liopteridae , and among the cynipids, the tribes Qwaqwaini, Phanacidini , Pediaspidini , Paraulacini , and Eschatocerini ; among the figitids, Parnipinae , Thrasorinae , Pycnostigminae , Emargininae , Euceroptrinae , Plectocynipinae , and Mikeiinae . If the user arrives at any of these using the key, we suggest double-checking the characters before making a final decision.

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.

As the basic identification of many of these groups is a general impediment to taxonomic progress, this key, and the taxonomic treatments that follow, provide a point of entry into cynipoid research not previously available. We hope this publication spurs renewed interest in cynipoid systematics, biology, and evolution.

Identification Key to Families, Subfamilies, andTribes of World Cynipoidea 1. Metasomal segment four, five or six the largest (in lateral view), with two to four small segments preceding largest segment (a, Fig. 1). Wings always fully formed, with marginal cell of forewing sometimes very elongate. Often large wasps, exceeding 10 mm in length. Mesoscutum with heavy sculpture (well-developed ridges or pits; b, Fig. 1; arrows, Fig. 2) ........................................................................................................ 2 — Metasomal segment two or three the largest (in lateral view), or fused into a syntergum (arrows, Figs. 3 and 4), with at most one or two segments preceding the largest (arrows, Figs. 5 and 6). Wings usually fully formed; marginal cell of forewing usually shorter, rarely as long as 3× as long as high. Adult wasps smaller than 10 mm in length. Deep ridges in mesoscutum less common; typically microcoriaceous or smooth ........................................................................................................................................................................................................................ 3 2. Marginal cell of forewing extremely elongate (9× as long as high) (arrow, Fig. 7). Metasoma in dorsal view elongate and very laterally compressed, thin, blade-like (arrow, Fig. 8). Large, over 20 mm in length .................................................................................................. Ibaliidae — Marginal cell of forewing moderately elongate (3–4× as long as high) (a, Fig. 9). Metasoma in dorsal view rounded, ovate, subcylindrical (arrow, Fig. 10). Size varying, sometimes small, always under 20 mm ............................................................................................. Liopteridae 3. With a pterostigma (arrow, Fig. 11), always fully winged. No foveae or lateral bars on scutellum (a, Fig.12). Mesoscutum with welldeveloped transversal ridges (b, Fig. 12). Australia only, very rare ........................................................................................... Austrocynipidae — Without a pterostigma (arrows, Figs. 13 and 14) (very rarely the entire marginal cell is pigmented forming a pseudostigma; arrow, Fig. 15), rarely brachypterous/apterous. Usually with more or less developed foveae and lateral bars of scutellum (arrows, Fig. 17). Mesoscutum usually without well-developed transversal ridges ( Figs. 16 and 17). Worldwide ........................................................................................................ 4 4. Fully winged ( Figs. 18–20). Note: brachypterous/wingless forms, or specimens with obscured, tangled or damaged wings, can be identified via this route too ............................................................................................................................................................................................ 5 — Brachypterous or apterous ( Figs. 21–23) (shortcut route to groups where this feature is known) ............................................................ 33 5. Rs+M vein often indistinct or absent (arrow, Fig. 24); its proximal part, when present as a faint vein ( Fig. 26) or a fold ( Fig. 25) joins basal vein at ventral end of basal vein (a, Fig. 26). Areolet usually absent. Usually head and mesosoma shiny ( Figs. 28 and 29), rarely rugose or matte ( Fig. 27). Scutellum often complex, with differentiated structures such as, plates, spines etc ........................................................................... 6 — Rs+M starts at (or points towards) mid-length of basal vein (Rs+M, Figs. 30–35). Aerolet often present (are, Figs. 30–35). Usually large parts of head and mesosoma matte ( Figs. 36 and 39), rarely smooth/shiny ( Figs. 37 and 38). Scutellum distinct structure other than general fovea or rugosity (most of Cynipidae ) ............................................................................................................................................................ 8 6. Head, pronotum and mesoscutum shiny, more or less smooth, and usually not densely pubescent ( Figs. 40–42) (most of Figitidae ) ........ 19

— Head, pronotum and mesoscutum matte from dense microsculpture, and more or less densely pubescent ( Figs. 43–45) ........................... 7 7. With dense pubescence on base of metasoma (arrow, Fig. 46). Usually with distinct pronotal plate (arrows, Fig. 47). Often with complex structure on scutellum (arrow, Fig. 48) (some Figitidae ) ............................................................................................................................... 19

— Usually without dense pubescence on base of metasoma ( Fig. 49) but sometimes with small lateral patch (arrow, Fig. 50). Usually without distinct pronotal plate (arrow, Fig. 51). Always with a relatively simple scutellum dominated by evenly distributed fovea or rugosity (arrow, Fig 49) (some Cynipidae ) ............................................................................................................................................................................... 8 8. Pronotum high, dorsomedially at least 1/5, usually 1/3, as long as greatest length of pronotum laterally (arrows, Figs. 52–55). The median area of pronotum with two submedian pits and often more or less sharply defined lateral demarcations. Pronotal plate present or absent ................. 9 — Pronotum low, dorsomedially short, 1/7 or less compared to length of pronotum laterally (arrows, Figs. 56–59). Median area of pronotum without well-defined structures, at most with superficial depressions. Pronotal plate always absent ............................................................. 17 9. Scutellar foveae shallow, usually faint to completely absent (oval, Fig. 60). Mesopleuron with a median longitudinal mesopleural impression, sometimes very faint (arrows, Fig. 61) or absent. Inhabiting galls on Nothofagus or inducing galls on Acer (including the genus Hymalocynips from Nepal with biology unknown). Rarely encountered ............................................................................................................................. 10 — Scutellar foveae usually well differentiated and deep, sometimes confluent and forming a transverse depression (circles, Fig. 62). Mesopleuron without a median longitudinal impression (arrow, Fig. 63) .......................................................................................................................... 11 10. Female antenna with 12 or more flagellomeres; last flagellomere not wider than the penultimate (ant, Fig. 64); male antenna without modified F1. Ventral area of gena without vertical carinae, genal carina absent. Ventral part of clypeus broadly projecting over mandibles (cly, Fig. 64). Dorsolateral margin of pronotal plate not projecting laterad (Fig. 65). Mesopleural impression absent or faint (mpi, Fig. 65). Profemur not modified. Palearctic gall-inducers on Acer or biology unknown .............................................................................................. Pediaspidini — 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). Mesopleural impression present (mpi, Fig. 67). Profemur with ventral swelling composed of 4–5 rows of sharp, closely spaced, deep costulae. Associated with Neotropical galls on Nothofagus ..................................................................................................................................................................................... Paraulacini 11. Occiput with strong and sharp occipital carina (arrows, Fig. 68). Hypopygium abrupt, not prolonged into a ventral spine; with a dense tuft of long setae (arrow, Fig. 69). South African gall-inducers on Scolopia . Rarely encountered ......................................................... Qwaqwaiini — Occiput without distinct and sharp occipital carina (arrow, Fig. 70), sometimes with some strong parallel occipital rugae. Hypopygium with more or less distinct, elongated, needle-like ventral spine, with subapical setae never forming a dense tuft (Fig. 71) .................................... 12 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 ( Figs. 72 and 73), sometimes with indistinct and continuous suture between these terga in either sex. Head and mesosoma almost always sculptured ( Figs. 74 and 75). Metasoma anteroventrally angled, relative to midline, in lateral view (mt, Fig. 72). Holarctic and Oriental inquilines in galls .......................................................................................................................................................................................................... 13 — Terga 2–7 free in most cases ( Fig. 76); if terga 2 + 3 fused in females into one large segment then head and mesosoma almost always smooth and shiny (otherwise, head and mesosoma sculptured) (Fig. 77). Metasoma usually more or less oval in lateral view (mt, Fig. 76. Holarctic gall-inducers on herbaceous plants or Rubus ................................................................................................................................................ 14 13. Metasomal T2 separated from T3 by suture; T2 much smaller than T3 ( Fig. 78); first tergum hardly visible ( Fig. 78). Depression present ventral of torulus (arrows, Fig. 79). Upper face, mesopleuron and vertex smooth. Metasoma hair patch often present. Pronotal plate complete ....................................................................................................................................................................................................... Ceroptresini — Second and third tergum of metasoma fused into syntergum (T2 + 3, Fig. 80); no suture present between T2 and T3; first tergum relatively large, ring-like, longitudinally sulcate (arrow, Fig. 80). Depression absent ventral of torulus (though striae frequently present) (Fig. 81). Upper face, mesopleuron and vertex with various degrees of sculpture, not smooth. Pronotal plate incomplete dorsally .............................. Synergini 14. Pronotal plate present, defined dorsally and ventrally (pt. Fig. 82). Mesopleuron and mesosoma smooth (msp, Fig. 83). Most females with 10 flagellomeres in antenna. Metatarsal claws with distinct lobe. Gallers and inquilines on Rosaceae , or host unknown .............. Diastrophini — Pronotal plate incomplete, not defined dorsally (pt, Figs. 84 and 85). Mesopleuron and mesosoma sculptured to various degrees (msp, Figs. 86 and 87). Most females with more than 10 flagellomeres in antenna. Metatarsal claws simple. Gallers on various herbaceous plants ................. 15 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). R 1 in forewing reaching anterior margin of wing (R1, Fig. 90), and marginal cell at least partially closed ( Fig. 90). Gallers on Asteraceae , rarely on other plants .................................... Phanacidini — Mesopleuron longitudinally striate, striate-reticulate, or smooth, never rugulose (msp, Figs. 91 and 92). Submedian depressions of pronotal plate present, typically separated (ad, Fig. 93). Dorsal part of pronotal plate typically reaching mesoscutum. R1 of forewing reaching or not reaching wing margin (R1, Fig. 94). Marginal cell open or closed ( Fig. 94)................................................................................................... 16 16. Mesopleuron striate-reticulate or reticulate (msp, Fig. 95); female antenna with 12 flagellomeres; pronotum (in dorsal view) short, about 1/5 as long as greatest length of outer margin (pt, Fig. 96); admedian depressions narrowly separated and strongly transverse (ad, Fig. 96); gallers on Papaver (Papaveraceae) ........................................................................................................................................................ Aylacini — Mesopleuron longitudinally striate (msp, Figs. 97 and 98); female antenna with 10–11 flagellomeres; pronotum (in dorsal view) longer, about 1/3 to 1/4 as long as greatest length of outer margin (pt, Figs. 99 and 100); admedian depressions oval or round, usually more widely separated (ad, Fig. 100); gallers on Asteraceae , Lamiaceae , Valerianaceae , and Papaveraceae ......................................................... Aulacideini 17. Frons between antennal toruli with strong longitudinal carina (arrow, Fig. 101); notauli and scutellar foveae absent ( Fig. 102); mesoscutum bulging above pronotum (arrow, Fig. 103); Rs+M and R1 of forewing inconspicuous, marginal cell with Rs separate from anterior wing margin; basal vein absent ( Fig. 104); Neotropical gall-inducers on Acacia or Prosopis ............................................................... Eschatocerini — Frons usually without median carina ( Fig. 105); if present, (some Plagiotrochus ) then it is not so strong and cannot be readily differentiated from Fig. 101. Notauli complete, incomplete or absent ( Fig. 106). Scutellar foveae present or confluent, forming shallow transverse depression in lateral view. Mesoscutum not bulging above pronotum (arrow, Fig. 107); Rs+M and R1 of forewing usually present and visible, Rs reaching or almost reaching anterior wing margin. Basal vein present ( Fig. 108) in forewing. Gall-inducers on Fagaceae or Rosa .............................. 18 18. Mesopleuron with a broad, crenulate mesopleural impression (arrow, Fig. 111). Usually with a combination of the following character states: hypopygium plough-shaped (arrow, Fig. 109); lateral propodeal carinae indistinct; scutellar foveae faint or absent ( Fig. 112); 2r of forewing with a median vein stump projecting distad (arrow, Fig. 110); Holarctic gall-inducers on Rosa .......................................... Diplolepidini — Mesopleuron usually without a mesopleural impression ( Fig. 113; arrow, Fig. 115). Without other characters combined ( Figs. 113–116). Holarctic and Oriental gall-inducers on Fagaceae , mainly Quercus ..................................................................................................... Cynipini 19. Marginal cell sclerotized into a pseudostigma (arrows, Figs. 117 and 118). Afrotropical and southeastern Palearctic/Middle East .................................................................................................................................................................................................. Pycnostigminae

— Marginal cell not sclerotized (arrow, Fig. 119) ......................................................................................................................................... 20 20. Scutellum with an elevated scutellar plate (a, Fig. 120); with a glandular release pit (b, Figs. 121 and 122) ............................... Eucoilinae

— Structure of scutellum variable, posterior surface relatively flat or evenly convex, never with a distinct elevated plate and associated posterior release pit ( Figs. 123–128) .................................................................................................................................................................. 21 21. Apex of forewing deeply bilobed (arrow, Fig. 129). Often raised median area on scutellum. Densely packed (foamy) setae present on propodeum (arrow, Fig. 130). Typically 1.5 mm in length ............................................................................................................ Emargininae — Apex of forewing rounded (arrow, Fig. 131). Propodeum variously setose to glabrous, never with densely packed setae (Fig. 132) ......... 22 22. Areolet present (arrow, Fig. 133); base of metasoma setose or glabrous ( Fig. 134) ................................................................................. 23

— Areolet absent (arrow, Fig. 135); base of metasoma glabrous ( Fig. 136) .................................................................................................. 25 23. Head and mesoscutum generally coriaceous to foveate, and frequently setose ( Fig. 137) ........................................................................ 24

— Head and mesoscutum generally smooth, lacking dense setal patterns, but some stout setae present (Fig. 138) .....................some Figitinae 24. Mesopleuron striate, with no indication of distinct mesopleural furrow (arrow, Fig. 139). Lateral pronotal carina absent. Mediterranean, on Papaver ...................................................................................................................................................................................... Parnipinae

— Mesopleuron dorsally smooth, ventrally striate along the distinct mesopleural furrow (arrow, Fig. 140). Lateral pronotal carina present. Nearctic, on Quercus ................................................................................................................................................................. Euceroptrinae 25. Head generally triangular in anterior view; mouth small, with broadly overlapping mandibles ( Fig. 141). Petiole often long (arrow, Fig. 142). First metasomal tergum subequal in length to second, sometimes longer .................................................................... Anacharitinae

— Head oval to round in anterior view ( Figs. 143 and 144); mouth region broadened, mandibles larger and not extensively overlapping. Petiole typically not elongate ........................................................................................................................................................................ 26 26. Scutellum evenly convex, rounded, smooth (arrows, Figs. 145 and 146). Usually tiny, very often pale in color ( Fig. 147). Mesoscutum usually shiny and smooth ( Figs. 145–147), rarely matte ........................................................................................................................ Charipinae

— Scutellum flat or weakly convex, and sculptured ( Figs. 148–150). Usually darker, typically black. Mesoscutum usually with transverse ridges or distinct microsculpture ( Figs. 148–150) ................................................................................................................................................... 27 27. Metatibial spur remarkably long, more than half the length of basal tarsomere (arrows, Figs. 151–153). Neotropical; associated with Nothofagus forests. Rarely encountered ................................................................................................................................... Plectocynipinae

— Metatibial spur not remarkably long, at most a quarter of length of first tarsomere (arrow, Fig. 154) ..................................................... 28 28. Facial impression present (arrow, Fig. 155). First metasomal tergum saddle-like with concave posterolateral margin and more or less linguiform median part (arrows, Fig. 157). Often relatively large, with a well sculptured body, often red color, and wings with strongly reduced pubescence and accessory veins ...............................................................................................................................................core Aspicerinae

— Facial impression absent (arrow, Fig. 156). First metasomal tergum rounded, usually with a convex margin (arrows, Fig. 158). Size varying from relatively large to very small ................................................................................................................................................................ 29 29. Short petiole, no flange or collar (arrow, Fig. 159). Inquilines, mostly in Australia and Neotropical region, very rare in Nearctic and East Palearctic regions. Rarely encountered .......................................................................................................................................................... 30

— Longer petiolar region, with a reduced basal metasomal tergum forming a collar or sheath over petiole (arrow, Fig. 160) ...................... 31 30. With a circumtorular impression (an impression above antennal insertion) (cti, Figs. 161 and 162). Often with a well-developed pronotal plate (pt, Fig. 162) ......................................................................................................................................................................... Thrasorinae

— Without a circumtorular impression (arrow, Fig. 163). Without a well-developed pronotal plate, just visible laterally (pt, Fig. 163). Australia only .................................................................................................................................................................................................. Mikeiinae 31. Without a metasomal hairpatch (arrow, Fig. 164). Eyes commonly setose (arrow, Fig 166) ................................................... core Figitinae

— With a metasomal hair patch (arrow, Fig 165). Eyes typically glabrous (arrow, Fig. 167) ........................................................................ 32 32. Mesoscutum typically shining, lacking microsculpture ( Fig. 168), frequently with long setae present ................................ several Figitinae

— Mesoscutum matte and leathery with dense microsculpture (Fig. 169) ..................................................................... Melanips (Aspicerinae) 33. Scutellum simple, without a distinct scutellar plate (arrows, Figs. 170 and 171) ..................................................................................... 34

— Scutellum surmounted by distinct scutellar plate (arrows, Figs. 172 and 173) ............................................................................. Eucoilinae 34. Metasoma about the size of the mesosoma ( Figs. 174 and 175); brachyptery ( Figs. 174 and 175) more common than aptery. Color variable but very often pale. Mesosoma usually not strikingly narrow. Scutellum evenly convex. Mainly in summer in the Holarctic Region ......................................................................................................................................................................................................... Charipinae

— Metasoma at least twice the size of mesosoma ( Figs. 176 and 177), both segments the same size; apterous ( Figs. 176 and 177) to brachypterous. Color from pale to dark brown. Mesosoma usually strikingly narrow. Scutellum rather flat. Mainly in the winter half of the year in the Holarctic Region.................................................................................................... Cynipini (alternate generation of winged forms)