Key to Adults of North American Genera of the Subfamily Cecidomyiinae

1 Antenna with 13 distinct flagellomeres, the last abruptly narrowed before apex (fig. 27). Rs complete and as strong as R5 (fig. 63).......................................................................... Supertribe Stomatosematidi 2

- Antenna with 7–42 flagellomeres; if with 13, the last not abruptly narrowed before apex. Rs rarely as strong as R5, usually lacking (fig. 64) or incomplete (fig. 74)....................................................................... 3

2(1) Body yellow except for persistent dark lateral stripe along side of thorax. Male cerci, hypoproct and aedeagus diminutive, less than half length of gonocoxite (fig. 109). Female cerci two-segmented (fig. 230).................... Didactylomyia Felt Cosmopolitan, including Eocene fossils, 12 spp., 1 Nearctic and cosmopolitan, D. longimana (Felt) .

- Body fuscous. Male cerci, hypoproct and aedeagus approaching length of gonocoxite (figs 110–112). Female cerci one-segmented (fig. 231)...................................................................... Stomatosema Kieffer Cosmopolitan, including Eocene fossils, 18 spp.; 2 Nearctic.

3(1) Antenna with 7 to more than 40 flagellomeres, the number often irregular within species, regularly 12 only in Lauthia . Gonocoxite usually with conspicuous mediobasal lobe, closely juxtaposed to aedeagus (figs 104–106) (unless diminutive as in some Brachineuridi (fig. 129)); aedeagus without sensoria (figs 104–106). Female cerci usually fused to form a single soft, cylindrical or bulbous lobe (fig. 234) or occasionally part of a stiff, pigmented structure (figs 235, 248–249), but the cerci discrete in the supertribe Brachineuridi (fig. 245) and a few Lasiopteridi (fig. 236)........................................... 4

- Antenna with regularly 12 flagellomeres (except more in a few species of Caryomyia and Planetella), not counting the occasional presence of a small bud beyond twelfth flagellomere. Gonocoxite usually without mediobasal lobe (fig. 179); if present, then well separated from aedeagus (figs 172–173); aedeagus with sensoria (as circular depressions, hardly ever setose) (fig. 177) except in Asphondyliini, and then the gonostyli are short and broad and situated dorsally on the gonocoxites (fig. 167). Female cerci usually discrete (fig. 274) but may be extremely tiny, dorsoventrally flattened and closely juxtaposed (fig. 277), completely or almost completely fused with the terminus of a needlelike ovipositor (most Asphondyliini (figs 267, 270), or, rarely, fused to form a single cylindrical lobe ( Procontarinia, Taxodiomyia (fig. 272))..........Supertribe Cecidomyiidi 75

4(3) R5 half to four-fifths as long as wing, straight, closely adjacent and parallel to R1 (fig. 65). Flagellomeres foreshortened, without necks, essentially similar in both sexes (figs 5–6, 28)..................................................................................................... Supertribe Lasiopteridi (in part: tribes Alycaulini and Lasiopterini) 5

- R5 nearly or fully as long as wing (figs 63, 68) or, if significantly shorter, then bowed away from R1 (figs 67, 69–70). Flagellomeres various, usually sexually dimorphic and with necks at least in males (10, 29).......................... 18

5(4) Eversible part of ovipositor with lateral group of numerous, long, robust, flattened setae, elsewhere covered with microtrichia; protrusible part evenly microtrichose; fused cerci with dorsobasal, glabrous area with prominent hooked setae (fig. 232). Male 7th and 8th tergites with reduced sclerotization and vestiture posteriorly, setae and scales lacking or present only laterally on 7th tergite (fig. 113) (except in Isolasioptera with fully developed 7th tergite)........................................................................................................ Supertribe Lasiopteridi, Tribe Lasiopterini 6

- Eversible part of ovipositor without group of enlarged lateral setae, mostly carinate, dorsal carinae serially interrupted at midlength to form a series of teardrop-shaped bumps; protrusible part mostly microtrichose except for dorsal, ovoid glassy-smooth area; cerci fused (except in Alycaulus), without hooked setae (fig. 234). Male 7th and 8th tergites with reduced sclerotization and vestiture anteriorly, 7th tergite and occasionally 8th with setae along posterior margin (fig. 114)........................................................................................Supertribe Lasiopteridi, Tribe Alycaulini 9

6(5) Mouthparts developed into a proboscis nearly as long as eye height, labella styliform................. Ozirhincus Rondani Palearctic, 4 spp., all in achenes of Anthemideae (Asteraceae), one, O. millefolii (Wachtl) introduced into North America from Europe with seeds of its host Achillea millefolium .

- Mouthparts not developed into a proboscis, labella hemispheroid................................................ 7

7(6) R5 about four-fifths wing length (fig. 66). Male 7th tergite with complete row of posterior setae. Female 8th tergite not divided longitudinally......................................................................... Isolasioptera Möhn Neotropical (El Salvador and Mexico), 2 spp., in stems of Eupatorium (Asteraceae) . This genus is the southernmost example of the tribe Lasiopterini in the New World.

- R5 two-thirds wing length or less (fig. 65). Male 7th tergite usually reduced in size compared to 6th tergite, with at most a few posterior setae laterally (fig. 113). Female 8th tergite divided longitudinally into 2 discrete sclerites (as for fig. 234)....... 8

8(7) Female fused cerci bilaterally compressed, darkly pigmented, completely glabrous (fig. 233). Male 7th tergite nearly same size as 6th, lacking only posterior row of setae............................................. Hybolasioptera Rübsaamen Holarctic, 2 spp., in culms of Elymus (Poaceae); 1 Nearctic, H. elymi Gagné

- Female fused cerci cylindrical, with only a dorsal, saddle-shaped area glabrous, remainder microtrichose with scattered setae

(fig. 232). Male 7th tergite greatly reduced in size compared to 6th (fig. 113)........................ Lasioptera Meigen Old World and Nearctic, 126 spp., mostly in stem galls on a wide array of plants, but a few are inquilines and successor species; 31 Nearctic.

9(5) Female fused cerci styliform (fig. 235). Male 1 st through 6th tergites with scales but without posterior setae...................................................................................................... Protaplonyx Felt W Nearctic, 1 sp., P. sarcobati (Felt), in stems of Sarcobatus vermiculatus (Chenopodiaceae) .

- Female cerci fused, bulbous or bilaterally flattened, or discrete (fig. 236). Male 1 st through 6th tergites with both scales and posterior setae....................................................................................... 10

10(9) Male 6th to 8th abdominal segments retractable (figs 115–116). Protrusible part of ovipositor with raised, falcate comblike microtrichia (fig. 237).................................................................. Meunieriella Kieffer New World, 21 spp., mostly inquilines in galls of other cecidomyiids, but at least two responsible for simple leaf galls; 2 Nearctic.

- Male 6th to 8th abdominal segments not retractable (fig. 114). Protrusible part of ovipositor with two- or many-pronged, flat, comblike microtrichia (fig. 243)......................................................................... 11

11(10) Male 6th and 7th tergites with anterior margins extended ventrally, nearly reaching sternites (fig. 121). Female indistinguishable from other Alycaulini with elongate-cylindrical cerci (fig. 239), will key to Neolasioptera ......... Calamomyia Gagné Nearctic, 19 spp; all probably from culms of grasses ( Poaceae). Only seven have been associated with particular hosts, these from five tribes of Poaceae .

- Male tergites rectangular, without ventrolateral extensions (fig. 114). Female fused cerci short-bulbous to elongate-cylindrical (figs 234, 239) or bilaterally compressed (figs 240, 242)...................................................... 12

12(11) Wing margin and abdomen covered entirely with black scales. Female 7th tergite extended anterolaterally (fig. 241)............................................................................................. Astictoneura Gagné Nearctic, 1 sp., A. muhlenbergiae (Marten), from an imbricated, broomlike stem gall on a Muhlenbergia (Poaceae) .

- Wing with white scales at juncture of R5 and C, strongly contrasting with dark scales elsewhere along C; abdomen with light and dark scale color pattern. Female 7th tergite with horizontal anterior margin (fig. 243). Only female Alycaulini keyed beyond this point: males not distinguishable to genus........................................................ 13

13(12) Protrusible part of ovipositor, including cerci, rigid, bilaterally compressed (figs 240, 242)........................... 14

- Protrusible part of ovipositor pliable, cylindrical, the cerci cylindrical or ovoid (figs 239, 243)........................ 15

14(13) Eighth tergite undivided longitudinally, slightly longer than 7th (fig. 240)....................... Xipholasioptera Gagné W Nearctic, 1 sp., X. ensata Gagné, on Baccharis pteronioides ( Asteraceae).

- Eighth tergite divided longitudinally, twice as long as 7th (fig. 242).............................. Edestosperma Gagné W Nearctic, 1 sp., E. aristidae Gagné, from seeds of Aristida longiseta (Poaceae) .

15(13) Venter below 8th tergite partly sclerotized (fig. 243). From grasses............................................. 16

- Venter below 8th tergite unsclerotized (fig. 234). From plants other than grasses................................... 17

16(15) Fused cerci bulbous (as for fig. 234). Pair of trichoid sensilla present on 8th sternite (as for fig. 135)..... Edestochilus Gagné W Nearctic, 1 sp., E. allioides (Pritchard), from an onionlike, basal swelling on stems of Paspalum distichum (Poaceae) .

- Fused cerci elongate-cylindrical (fig. 243). Pair of trichoid sensilla absent from 8th sternite (cf. fig. 135)....................................................................................................... Chilophaga Gagné Nearctic, 5 spp., forming broom-shaped galls on foreshortened stems or living gregariously in culms of grasses ( Poaceae).

17(15) Palpus usually of 4 segments, occasionally 3. Sternites with anterior pair of trichoid sensilla (as for fig. 135). Female 8th tergite elongate, divided longitudinally; protrusible part of ovipositor long, rarely less than 3 times length of 7th tergite (fig. 234)......................................................................................... Neolasioptera Felt New World, 134 spp., on a wide array of plants where they form mainly stem galls, but some form petiole, leaf vein or flower galls; 56 Nearctic.

- Palpus of 1–3 segments. Sternites without anterior pair of trichoid sensilla. Female 8th tergite quadrate, not divided longitudinally; protrusible part of ovipositor no longer than twice length of 7th tergite.......................... Asteromyia Felt Nearctic, 9 spp., all on Astereae (Asteraceae) where they form blister galls on leaves and green stems.

18(4) Flagellomeres foreshortened, without necks, barely longer than wide and essentially similar in both sexes (as for figs 5–6, 28). R5 less than 3/4 wing length, usually appreciably less (figs 7, 67)...............................................................................................Supertribe Lasiopteridi, tribes Trotteriini and Camptoneuromyiini 19

- Flagellomeres appreciably longer than wide, usually with necks and sexually dimorphic (figs 10–11). R5 usually joining C near, at, or behind wing apex (figs 64, 68); if much shorter than wing, M4 absent (fig. 69)........................... 20

19(4) Mid- and hindfemora successively broader than forefemur (fig. 7).....................Tribe Trotteriini, Trotteria Kieffer Cosmopolitan, 23 spp., inquilines in galls of other cecidomyiids, chiefly Asphondyliini; 2 Nearctic.

- All femora of approximately equal width............................Tribe Camptoneuromyiini, Camptoneuromyia Felt New World, mainly tropical, 15 spp., 6 Nearctic. Many appear to be inquilines in galls of other cecidomyiids.

20(18) Claws curved near midlength, at least foreclaws with basal tooth in most genera, the tooth long, thin (fig. 83). Antenna with regularly 8–9, 10, or 12 flagellomeres. Male 8th and usually also 7th tergites reduced to foreshortened, often darkly pigmented, horizontal sclerites, their only vestiture a pair of short, trichoid sensilla (figs 122, 135). Ovipositor with posteroventral notch (fig. 244), not protrusible except in Ledomyia (fig. 246); cerci discrete.......................Supertribe Brachineuridi 21

- Claws various, most often curved closer to apex than to base, with or without basal tooth or teeth, teeth short if present (figs 81–82). Antenna with 7–42 flagellomeres, the number nearly always irregular within a species. Male 7th and 8th tergites not reduced to uniformly short, dark, horizontal sclerites and usually at least 7th tergite with vestiture in addition to pair of trichoid sensilla (as for fig. 107). Ovipositor without posteroventral notch, usually elongate-protrusible; cerci rarely discrete, usually fused into a single soft, bulbous or cylindrical lobe (figs 7, 9, 247), and further modified in some genera, sometimes united with protrusible part of ovipositor to form a hard, piercing organ (figs 248–249).............................................................................................. remaining Lasiopteridi, not separated by tribes here 27

21(20) Scutum and abdomen evenly and thickly covered with scales, without setae. Flagellomeres lacking setae, node partly or wholly covered with dense scales (fig. 30)....................................................................... 22

- Scutum and abdomen with mixed setae and scales, scutum with 2 prominent, dorsocentral rows of setae. Flagellomeres with setae (fig. 31)........................................................................................ 23

22(21) Gonocoxite with apicoventral lobe (fig. 124); aedeagus bulbous at base, strongly recurved (fig. 125); female not separable in this couplet................................................................................. Epimyia Felt Holarctic, 2 spp.; 1 Nearctic, E. carolina Felt, associated with mushrooms.

- Gonocoxite without apicoventral lobe (fig. 126); aedeagus cylindrical, only slightly curved (fig. 127).. Brachineura Rondani Cosmopolitan, 28 spp., including Eocene fossils, associated with fungi and decaying vegetable matter; 3 Nearctic.

23(21) Antenna with 10 flagellomeres. Gonocoxal mediobasal lobe diminutive, glabrous, set apart from aedeagus (fig. 129)...... 24

- Antenna with 8–9, 10 or 12 flagellomeres. Gonocoxal mediobasal lobe large, at least partly microtrichose, closely juxtaposed to aedeagus (fig. 134)................................................................................. 26

24(23) R5 about two-thirds or less wing length (fig. 69). Male with only 8th tergite reduced to thin horizontal sclerite.................................................................................................. Chrybaneura Gagné Widespread New World, 1 sp., C. harrisoni Gagné, associated with spider egg shells and remains of dead insects.

- R5 as long as wing or slightly shorter (figs 68, 70). Male with both 7th and 8th tergites reduced to thin horizontal sclerites (as for fig. 122)......................................................................................... 25

25(24) M4 present, forming a fork with CuA (as for fig. 64). Claws with basal tooth (fig. 83). Male hypoproct with ventral spine (fig. 131).................................................................................. Rhizomyia Kieffer Holarctic, Oriental, 30 spp.; 8 Nearctic.

- M4 absent (fig. 68). Claws without basal tooth. Male hypoproct without apicoventral spine.............. Coccidomyia Felt Nearctic, 1 sp., C. pennsylvanica Felt, associated with insect remains.

26(23) Antenna with 8–9 or 10 flagellomeres. Gonostylus foreshortened, enlarged at tooth (figs 132–133) Ovipositor elongate-protrusible (fig. 246)........................................................................ Ledomyia Kieffer Cosmopolitan, also Eocene fossils, 27 spp.; 7 Nearctic, several from xylem vessels of fresh-cut logs.

- Antenna with 10 or 12 flagellomeres. Gonostylus elongate, widest at base, tapered to tooth (fig. 130). Ovipositor barely protrusible.................................................................................. Lauthia Kieffer Cosmopolitan, 28 spp.; 7 Nearctic, larvae of some living in xylem vessels of fresh-cut logs, others from rotting vegetable matter and fungi.

27(20) C not interrupted immediately posterior to juncture with R5 (fig. 71); if condition questionable, assume C is not interrupted...................................................................................................... 28

- C clearly interrupted immediately posterior to juncture with R5 (figs. 64, 66, 68)................................... 55

28(27) Claws with basal tooth or teeth, at least on some legs (fig. 81)................................................. 29

- Claws simple, without basal tooth (fig. 82)................................................................ 39

29(28) Palpus of 1–3 segments................................................................................ 30

- Palpus of 4 segments.................................................................................. 32

30(29) Pulvilli as long as claws; empodia narrow, barely wider than pulvilli (fig. 84)...................... Psectrosema Kieffer Palearctic, 26 spp., all on Tamarix ( Tamaricaceae). Some may eventually be introduced into SW North America for control of tamarix.

- Pulvilli usually much shorter than claws (as for fig. 81); if approaching full length of claws, empodia padlike, much wider than pulvilli (fig. 85)...................................................................................... 31

31(30) Pulvilli diminutive, less than one-third length of claws (fig. 81). Aedeagus appreciably shorter than gonocoxite (figs 1 37–138). Female cerci fused (fig. 250).................................................. Rhopalomyia Rübsaamen (in part) Cosmopolitan, 267 spp., associated almost exclusively with galls on Asteraceae; 84 Nearctic.

- Pulvilli more than half length of claws. Aedeagus nearly as long as gonocoxite (figs 139–140). Female cerci discrete (fig. 25 1)....................................................................................... Lonicerae Gagné W Nearctic, 2 spp., in bud galls on Lonicera (Caprifoliaceae) .

32(29) Tergites without scales (fig. 252). Pulvilli as long as claws (fig. 85). Male flagellomere necks somewhat longer than nodes (fig. 33).................................................................................... Primavera Gagné E Nearctic, 1 sp., P. porrecta (Felt), in samaras of Ulmus americana (Ulmaceae) .

- Tergites with scales. Pulvilli less than one-third as long as claws (fig. 81). Male flagellomere necks somewhat shorter than nodes (as for fig. 29).................................................................................. 33

33(32) Protrusible part of ovipositor, including fused cerci, bilaterally flattened, rigid (fig. 253). Male hypoproct with sharply acute apical lobes (fig. 141)............................................................ Procystiphora Felt (in part) Holarctic, 5 spp., in culms of Cyperaceae, Juncaceae and Poaceae; 2 Nearctic.

- Protrusible part of ovipositor and cerci cylindrical, flexible (as for fig. 254). Male hypoproct entire or with rounded apical lobes (figs 104, 136).................................................................................. 34

34(33) Claws polymorphic, some legs of same individual with 1-3 points on basal tooth (fig. 86), some lacking basal tooth...... 35

- Claws with single basal tooth on all legs (fig. 81)............................................................ 36

35(34) Claws of some legs with 1-2 points apically and 1-3 points on basal tooth (fig. 86), of others with single point apically and with single or no basal tooth. Protrusible part of ovipositor with lateral sclerites (as for fig. 254).............. Peracecis Gagné Nearctic, 1 sp., P. fugitiva Gagné, in leaf galls on Celtis (Cannabaceae) .

- Claws with any basal teeth single-pointed. Protrusible part of ovipositor without lateral sclerites (as for fig. 262)................................................................................................. Gliaspilota Gagné Nearctic, 1 sp., G. glutinosa Gagné, in slight leaf depressions of Carya spp. ( Juglandaceae).

36(34) Tergites without lateral setae (fig. 152).................................................................... 37

- Tergites with lateral setae (as for fig. 107)................................................................. 38

37(34) Gonocoxal apodeme united (as for fig. 163). Protrusible part of ovipositor with solid lateral sclerites (fig. 254)........................................................................................... Vitisiella Fedotova (in part) Holarctic, 3spp., leaf gall makers on grape, Vitis spp. ( Vitaceae); 1 E Nearctic, V. brevicauda (Felt) .

- Gonocoxal apodeme divided (as for fig. 145). Protrusible part of ovipositor with lateral sclerites composed of closely-set, parallel, slanted lines (as for fig. 250)............................................... " Rabdophaga ” cephalanthi Felt Nearctic, 1 sp., “ R. ” cephalanthi Felt, from stems of buttonbush, Cephalanthus occidentalis (Rubiaceae) . This species does not properly fit into any known genus of Lasiopteridi.

38(36) Katepisternum with scales. Claws with robust basal tooth (fig. 87). Gonostylus partially glabrous and carinate on dorsum (as for fig. 163). Protrusible part of ovipositor with prominent lateral sclerite along its length (as for fig. 255)........................................................................................... Rabdophaga Westwood (in part) Holarctic, 77 spp.; 29 Nearctic, most from galls on Salix, one from Populus (Salicaceae) . The species that form bud galls will run to this couplet; those in stem galls may key elsewhere.

- Katepisternum without scales. Claws with fine basal tooth (fig. 88). Gonostylus completely microtrichose, without carinae (fig. 144). Protrusible part of ovipositor without apparent lateral sclerites along its length (fig. 257)....... Mayetiola Kieffer Mostly Palearctic, 29 spp., all in culms of Poaceae; 2 Nearctic: M. destructor (Say), an immigrant pest of Triticum spp. and occasionally other grasses, and the Atlantic coast native, M. ammophila Gagné, on Ammophila breviligulata.

39(28) Palpus of 1–3 segments................................................................................ 40

- Palpus of 4 segments................................................................................. 48

40(39) Sternites appreciably longer than wide. Tergites with lateral group of setae closer to anterior than to posterior margin of sclerite..................................................................................... Chiosperma Gagné W. Nearctic, 1 sp., C. turgidum, bud gall maker on Symphoricarpos albus (Caprifoliaceae) .

- Sternites shorter than wide. Tergites with lateral group of setae situated at midlength of sclerites...................... 41

41(40) Empodia appreciably longer than claws (figs 89–90)......................................................... 42

- Empodia not appreciably longer than claws when both seen on same plane (as for fig. 81)........................... 44

42(41) Tergites with many lateral setae (as for fig. 107)................................................. Walshomyia Felt W Nearctic, 5 spp., all on Cupressaceae .

- Tergites without lateral setae............................................................................ 43

43(42) Eyes broadly joined at vertex (as for fig. 16). Empodia about one and a half times as long as claws (fig. 89). Female cerci fused...................................................................................... Semudobia Kieffer Holarctic, 7 spp.; all from bracts or fruit of Betula (Betulaceae); 5 Nearctic, 2 of them immigrants.

- Eyes not joined at vertex (as for fig. 17). Empodia about twice as long as claws (fig. 90). Female cerci usually fused, but discrete on at least O. betheli Felt. ......................................................... Oligotrophus Latreille Holarctic, 10 spp., all on Cupressaceae; 3 Nearctic.

44(43) Ovipositor bilaterally flattened, the protrusible part rigid (fig. 248). Gonocoxite with narrow, glabrous mediobasal lobes (as for fig. 157)................................................................................ Lygocecis Gagné Holarctic, 4 spp., all in stems of Salix (Salicaceae); 2 Nearctic.

- Ovipositor cylindrical, flexible, the fused cerci spheroidal (as for fig. 250). Gonocoxite with broadly rounded, longmicrotrichose mediobasal lobes (as for figs 105–106)........................................................ 45

45(44) Palpus of 3 segments. Gonostylus partly glabrous dorsally (as for figs 163–164). Protrusible part of ovipositor with solid lateral sclerites (as for fig. 254)................................................................. Iteomyia Kieffer Holarctic, 5 spp., all in leaf galls on Salix (Salicaceae); 2 Nearctic.

- Palpus of 1–2 segments. Gonostylus entirely microtrichose (as for fig. 144). Protrusible part of ovipositor with lateral sclerites either absent or composed of closely-set, parallel, slanted lines (fig. 250)............... Rhopalomyia Rübsaamen (in part) Cosmopolitan, 267 spp., associated almost exclusively with galls on Asteraceae; 84 Nearctic.

46(39) Tergites without scales (fig. 258)........................................................................ 47

- Tergites with scales (fig. 257).......................................................................... 48

47(46) Female cerci discrete (fig. 256). Gonocoxal apodeme divided (figs 145–146)......................... Acericecis Gagné Holarctic; 5 species, all from leaf galls of maple ( Acer spp.; Aceraceae); 2 Nearctic, one of them a Miocene fossil. The extant American species, A. ocellaris (Osten Sacken), lives in a glutinous substance in a slight circular depression on the underside of leaves.

- Female cerci fused, slender, rigid, dorsally recurved (fig. 258). Gonocoxal apodeme undivided (fig. 147)..... Ribesia Gagné Nearctic, 1 sp., R. sarae Gagné, in leaf blisters of Ribes (Saxifragaceae) .

48(46) Empodia appreciably longer than claws (as for fig. 89)........................................... Piceacecis Gagné Holarctic, 2 spp., in shoot galls on Picea (Pinaceae); one each Nearctic and Palearctic, the latter a recent arrival in E Nearctic.

- Empodia not appreciably longer than claws when both seen on same plane (fig. 81)................................ 49

49(48) Katepisternum with scales. Tergites, at least on 4th through 7th segments, with posterior setae in several horizontal rows and discontinuous medially............................................................. Rabdophaga Westwood (in part) Holarctic, 77 spp., 29 Nearctic. All form galls on Salix except one on Populus (Salicaceae) . Only R. rigidae (Osten Sacken) will end at this couplet; other Rabdophaga spp. will key elsewhere.

- Katepisternum without scales. Tergites with posterior setae in one or more horizontal rows, not discontinuous medially.... 50

50(49) Lateral setae numerous on all tergites (fig. 107)............................................... Helianthecis Gagné Nearctic, 1 sp., H. capitum Gagné, in heads of Helianthus spp. ( Asteraceae).

- Lateral setae absent on at least 1 st through 6th tergites (as for fig. 237).......................................... 51

51 (50) Gonostylus completely microtrichose (as for fig. 144). Female fused cerci wedge–shaped in dorsal view (fig. 260)....... 52

- Gonostylus carinate and glabrous on at least apical third of dorsal surface (as for figs 163–164). Female fused cerci bulbous or cylindrical (fig. 257).................................................................................. 53

52(51) Gonostylus widest near base (as for fig. 163). Ovipositor short, protrusible part less than twice length of 7th tergite, covered with dense, decumbent microtrichia; fused cerci only twice as long as hypoproct (fig. 260)............ Craneiobia Kieffer Holarctic, 2 spp., in tubelike galls on leaves of Cornus (Cornaceae); 1 Nearctic, C. tuba (Stebbins) .

- Gonostylus widest near midlength (as for fig. 145). Ovipositor long, protrusible part three times length of 7th tergite, covered with discrete, erect microtrichia; fused cerci three times as long as hypoproct (fig. 255)........ " Mayetiola " californica Felt Nearctic, 1 sp., “ M. ” californica Felt, from unspecified gall on Ribes menziesii (Grossulariaceae) in California. This species does not properly fit into any known genus of Lasiopteridi.

53(51) Sternites with scales covering area between posterior and middle rows of setae............ Rabdophaga Westwood (in part) Holarctic, 77 spp., all gallformers on Salix except two on Populus (Salicaceae); 29 Nearctic. Only four of our species without scales on katepisternum and with simple claws will end at this couplet.

- Sternites without scales between posterior and middle rows of setae.............................................. 54

54(53) Mediobasal lobes of gonocoxite tapered apically, aedeagus tapered to pointed apex (fig. 154). Lateral sclerites of protrusible part of ovipositor strongly apparent, widest anteriorly (fig. 254)............................ Vitisiella Fedotova (in part) Holarctic, 3spp., leaf gall makers on grape, Vitis spp. ( Vitaceae); 1 Nearctic, V. brevicauda (Felt) .

- Mediobasal lobes of gonocoxite blunt, aedeagus cylindrical, blunt at apex (fig. 156) Lateral sclerites of protrusible part of ovipositor, if apparent, of equal width throughout (as for fig. 255)..................................... Celticecis Gagné Holarctic; 23 spp, all forming complex, dehiscent leaf and stem galls on hackberries, Celtis spp. ( Cannabaceae); 21 Nearctic.

55(27) Claws without basal tooth (fig. 82)....................................................................... 56

- Claws with basal tooth (fig. 81)......................................................................... 61

56(55) Empodia appreciably longer than claws (as for fig. 89) (if only barely longer, follow alternative)...................... 57

- Empodia not longer than or barely exceeding claws (fig. 81).................................................. 58

57(56) Male 2nd to 6th tergites with posterior row of setae interrupted medially. Female 8th tergite three times longer than 7th, divided into 2 separate longitudinal sclerites (fig. 261)........................................... Strobilotia Gagné Nearctic, 1 species, S. carpophaga (Tripp), in cones of Picea glauca (Pinaceae) .

- Male 2nd to 6th tergites with posterior row of setae continuous across entire sclerite. Female 8th tergite barely longer than 7th, undivided (fig. 262)...................................................................... Cupressatia Gagné W Nearctic, 2 spp., in seeds of Cupressaceae, one of them accidentally introduced into Europe with its American host.

58(56) Palpus of 4 segments.................................................................................. 59

- Palpus of 1–3 segments................................................................................ 60

59(58) Male flagellomeres without necks (fig. 32). Male tarsi inflated, appreciably wider than femora and tibiae (fig. 80). Female with 10 or fewer flagellomeres.......................................................... Arnoldiola Strand (in part) Holarctic, 16 spp., most associated with Quercus and Castanea; 5 Nearctic.

- Male flagellomeres with necks (as for fig. 29). Male tarsi no wider than tibiae. Female with 12 or more flagellomeres.............................................................................................. Janetiella Kieffer Holarctic, 22 spp., a diverse assemblage on a wide array of plants; 5 Nearctic.

60(58) Ovipositor gradually tapered to bulbous fused cerci; 7th and 8th tergites and 7th sternite well delineated, with setae and scales (as for fig. 263). Gonocoxal mediobasal lobes broad, entirely microtrichose (as for fig. 105).................................................................................................... Rhopalomyia Rübsaamen (in part) Cosmopolitan, 267 spp., associated almost exclusively with galls on Asteraceae; 84 Nearctic.

- Ovipositor abruptly narrowed beyond 8th tergite, slender, rigid, dorsally recurved; 7th and 8th tergites and 7th sternite not delineated, vestiture of each reduced to anterior pair of trichoid sensilla (fig. 249). Gonocoxal mediobasal lobes slender, glabrous, no wider than aedeagus (fig. 157).......................................................... Sackenomyia Felt (in part) Holarctic, 5 spp., in simple leaf blister galls on Viburnum (Caprifoliaceae); 3 Nearctic.

61(55) Empodia appreciably longer than claws (as for fig. 89)....................................................... 62

- Empodia not or barely longer than claws (fig. 81)........................................................... 63

62(61) Palpus of 1–4 short segments, if more than one, all subequal in length. Gonostylus completely microtrichose (as for fig. 104)........................................................................................ Cembrotia Gagné W Nearctic, 1 sp., C. coloradensis (Felt), and at least 2 more undescribed; all responsible for needle galls on Pinus edulis (Pinaceae) .

- Palpus of 4 segments, the last two appreciably longer than the first two. Gonostylus glabrous and carinate on distal half (as for figs 163–164)...................................................................... Kaltenbachiola Hedicke Holarctic, 3 spp., all in cones of Picea (Pinaceae); 2 Nearctic.

63(61) Palpus of 1–3 segments................................................................................ 64

- Palpus of 4 segments.................................................................................. 66

64(63) Antenna with more than 25 flagellomeres, necks present in both sexes. First tarsomere with pointed ventroapical extension. Female fused cerci flexible, elongate, microtrichose. Gonocoxite with elongate ventroapical lobe........... Ficiomyia Felt SE Nearctic, Neotropical; 1 sp., F. perarticulata Felt, in fruit of Ficus (Moraceae) .

- Antennae with fewer than 15 flagellomeres, necks not prominent in females. First tarsomere without pointed ventroapical extension. Female cerci fused into a stiff, short, narrow, glabrous structure (figs 249, 264). Gonocoxite without elongate ventroapical lobe........................................................................................ 65

65(64) Female 7th tergite and 7th sternite not delineated, defined only by their anterior trichoid sensilla (fig. 249). Gonocoxal mediobasal lobes slender and glabrous throughout; gonostylus partly glabrous (fig. 157)......... Sackenomyia Felt (in part) Holarctic, 5 spp., larvae in simple leaf blister galls on Viburnum (Caprifoliaceae);.3 Nearctic.

- Female 7th tergite and 7th sternite well defined and setose (figs 264). Gonocoxal mediobasal lobes broad and microtrichose; gonostylus completely microtrichose (fig. 158)................................................ Cystiphora Kieffer Holarctic, 7 spp., all in blister galls in stems and leaves of Cichorieae (Asteraceae); 4 Nearctic, 3 of them introduced from Europe.

66(63) Protrusible part of ovipositor and fused cerci somewhat bilaterally flattened, rigid, glabrous (figs 253, 266). Gonocoxal mediobasal lobe broadly rounded, apical setae not elevated atop enlarged bases (figs 165–166)...................... 67

- Ovipositor cylindrical, cerci flexible, microtrichose (as for fig. 247). Gonocoxal mediobasal lobe tapered, apical setae atop enlarged bases (as for figs 105–106)...................................................................... 69

67(66) Female fused cerci with minute, longitudinal carinae on surface (fig. 253). Gonostylus completely microtrichose (as for fig. 144).................................................................................. Procystiphora Felt (in part) Holarctic, 5 spp., in culms of Cyperaceae, Juncaceae and Poaceae; 2 Nearctic.

- Female fused cerci with glabrous or microtrichose surface, without carinae (fig. 266). Gonostylus glabrous and carinate apically and on most of venter (fig. 165)............................................................................ 68

68(67) Female fused cerci with long, evenly distributed setae. Gonostylus tapered to a point but without definite tooth..................................................................................................... Coniophora Nijveldt Holarctic, 5 species; 1 Nearctic, the introduced C. graminicola Nijveldt on Phalaris arundinacea ( Poaceae).

- Female fused cerci mostly bare, with cluster of short setae near apex (fig. 266). Gonostylus with definite tooth at apex (fig. 165)................................................................................... Gephyraulus Rübsaamen Palearctic, Oriental, 13 spp., 11 on Brassicaceae, 2 on mango ( Anacardiaceae); one sp., G. mangiferae (Felt), a pest of mango introduced into the West Indies, not yet known from North America.

69(66) Sternites without anterior pair of trichoid sensilla (cf. fig. 135). Female cerci discrete (fig. 265)........... Rhizocecis Gagné Nearctic, 1 sp., R. rhois (Coquillett), on aerial root galls of Toxicodendron (Anacardiaceae) .

- Sternites 2nd through 7th with anterior pair of closely placed trichoid sensilla (fig. 135). Female cerci fused (as for fig. 247). Only males keyed beyond this point...................................................................... 70

70(69) Tarsi inflated, appreciably wider than tibiae (fig. 80)..................................... Arnoldiola Strand (in part) Holarctic, 16 spp., most associated with Quercus and Castanea; 5 Nearctic.

- Tarsi not wider than tibiae (as for figs 8–9)................................................................ 71

71(70) Gonostylus completely microtrichose (as for fig. 144)........................................................ 72

- Gonostylus microtrichose at base, glabrous and carinate beyond (as for figs 163–164).............................. 73

72(71) Eighth sternite mostly bare anteriad of posterior setal row. Gonocoxite with posteromedial bulge (fig. 159).... Spurgia Gagné Palearctic, 8 spp., on Euphorbia (Euphorbiaceae); 2 introduced into W North America from Europe for biocontrol of leafy spurge.

- Eighth sternite densely and completely covered with setae and scales. Gonocoxite not expanded posteromedially (figs 163–164).................................................................... Giraudiella Rübsaamen, Dasineura Rondani Giraudiella: Palearctic, 2 spp., one each in culms of Cyperaceae and Poaceae; the one on Poaceae, G. inclusa (Frauenfeld), an immigrant in E North America on the European form of Phragmites australis .

Dasineura: Cosmopolitan, a catchall genus of 478 species; 99 of them in North America, some accidentally introduced from Europe. Only 3 Nearctic species, evidently unrelated to one another, key here because of their fully microtrichose gonostyli: D. radifolii Felt, D. swainei (Felt) and D. toweri Felt.

73(71) Flagellomeres without necks. Gonocoxites greatly inflated, subspheroidal (fig. 161).................. Macrolabis Kieffer Holarctic, 61 Palearctic, mostly inquilinous in galls of other gall midges; 1 Nearctic, M. americana Dorchin on Solidago spp. ( Asteraceae).

- Flagellomeres with necks (except in Dasineura rhodophaga (Coquillett)) . Gonocoxites not greatly inflated along entire length, cylindrical (fig. 163)..................................................................................... 74

74(73) Gonocoxite in dorsoventral view with apicomedial bulge (fig. 162).............................. Jaapiella Rübsaamen Palearctic, 72 European and and western Asian species, on a diverse arrray of plants; J. gibsoni (Felt), was described from North America on the alien Cirsium arvense (Asteraceae) but is possibly a synonym of Jaapiella cirsiicola (Rübsaamen) . Two species have been introduced into W North America for the control of alien weeds: J. cirsiicola Rübsaamen from Cirsium spp. and J. ivannikovi Fedotova from Acroptilon repens (Asteraceae) .

- Gonocoxite in dorsoventral view cylindrical, without apicomedial bulge (fig. 163–164)............... Dasineura Rondani Cosmopolitan, a catchall genus of 478 species, 99 of them in North America, some accidentally introduced from Europe.

75(3) Male flagellomeres evenly cylindrical (figs 12, 34–35) except in Bruggmannia (fig. 36), circumfila usually anastomozing and closely juxtaposed to node (figs 34–36), never in 2 or 3 discrete horizontal series of loops. Gonostylus short and broad, situated dorsoventrally on gonocoxite (figs 167–170). Aedeagus without apparent sensoria. Female 7th sternite at least 1.5 times as long as 6th (figs 13, 267)................................................................... Asphondyliini 76

- Male flagellomeres usually with 2 distinct nodes, the circumfila in 2-3 series of loops (figs 37–38); if cylindrical (and similar in shape to those of female), usually with only 2 horizontal bands of appresssed circumfila connected by 2 vertical strands (fig. 39), rarely with numerous anastomozing strands (fig. 40). Gonostylus usually elongate. tapered, situated at apex of gonocoxite (fig. 171). Aedeagus with sensoria. Female 7th sternite not appreciably longer than 6th (fig. 15).remaining Cecidomyiidi (not separated by tribes here)............................................................................... 85 76(75) Palpus of 4 segments.................................................................................. 77

- Palpus of 1–3 segments................................................................................ 79

77(76) Gonocoxite short, stout, barely longer than wide (fig. 168). Female flagellomeres with anastomozing circumfila (fig. 60). Protrusible part of ovipositor stout, its setae pliable, much longer than cerci (fig. 269).................... Polystepha Kieffer Holarctic, Neotropical, 24 spp., all forming leaf galls on Quercus (Fagaceae); 18 Nearctic.

- Gonocoxite appreciably longer than wide (fig. 170). Female flagellomeres with simple circumfila (fig. 53). Protrusible part of ovipositor extremely attenuate, its setae not or barely detectable (fig. 270)........................................ 78

78(77) Gonostylar tooth extending across most of broad apical margin (fig. 170). Female cerci tiny but apparent (fig. 270).............................................................................................. Schizomyia Kieffer Cosmopolitan, 56 spp., mostly bud gall formers of a wide variety of plant families; 16 Nearctic.

- Gonostylar tooth extending over no more than half of apical margin, remaining margin occupied by a separate setose lobe. Female cerci undefined, subsumed into ovipositor shaft........................................ Burseramyia Möhn New World, 2 Neotropical spp. in flowers of Burseraceae; 1 undescribed E Nearctic, in flowers of Lamiaceae .

79(76) Legs with pointed, ventroapical extension of first tarsomeres (fig. 13)........................................... 80

- Legs without ventroapical extension of first tarsomeres....................................................... 83

80(79) Claws swollen near midlength (fig. 91)................................................. Hemiasphondylia Möhn Neotropical, 2 spp., from bud galls of Mimosoideae (Fabaceae); not yet known from tropical Mexico but presumably occurs there.

- Claws not swollen near midlength (fig. 92)................................................................ 81

81(80) Gonostylar tooth completely divided mesally (fig. 169)..................................... Bruggmanniella Tavares Nearctic, Neotropical, Oriental; 11 spp., found on a diverse array of plant families; 1 sp., B. bumeliae (Felt), from southern USA.

- Gonostylar tooth notched in middle but entire (fig. 167)...................................................... 82

82(81) Female antenna with last 5 flagellomeres progressively and conspicuously shortened (fig. 54)........... Asphondylia Loew Cosmopolitan, 299 species, all gall formers of a great number of plant families, a few species with alternate or multiple hosts; 75 Nearctic.................................................................................................

- Female antenna with only last 3 flagellomeres conspicuously shortened (fig. 55)................... Perasphondylia Möhn Neotropical, incl. Mexico, 2 spp., from bud galls on Eupatorieae ( Asteraceae).

83(79) Palpus of 1–2 segments. Protrusible part of ovipositor covered dorsally with many long setae (fig. 268).. Stephomyia Tavares Neotropical, Nearctic, 7 spp., all in leaf galls of Myrtaceae; 1 SE Nearctic, S. eugeniae (Felt) .

- Palpus of 3 segments. Protrusible part of ovipositor without long dorsal setae (fig. 271)............................. 84

84(83) Ovipositor elongate, pigmented, rigid, its setae, if apparent, extremely tiny and stiff. Male flagellomere nodes evenly cylindrical................................................................................... Pisoniamyia Möhn Neotropical, 3 spp., all on Pisonia (Nyctaginaceae), two from El Salvador, one from Mexico.

- Ovipositor not much longer than 7th sternite, flexible, with elongate, pliable ventral setae (fig. 271). Male flagellomere nodes usually constricted near basal third (fig.36)................................................ Bruggmannia Tavares Neotropical, 19 spp., from complex leaf galls, mostly on Nyctaginaceae; not yet known from Nearctic.

85(75) Head with occipital protuberance, bearing two prominent, anteriorly-directed setae (setae often lost in preparations but sockets remain prominent) (figs 18–19)......................................................................... 86

- Head lacking occipital protuberance (figs 21–23).......................................................... 147

86(85) Claws with basal tooth or teeth, at least on foreleg........................................................... 87

- Claws without basal tooth............................................................................. 103

87(86) Claws evenly bowed from base to apex or bent at or beyond midlength (figs 93, 98)................................ 88

- Claws strongly bent near basal third (figs 95, 103)........................................................... 93

88(87) Male flagellomeres bearing 1 circumfilum on each node (as for fig. 37). Female cerci fused into a single lobe (figs 272–273)........................................................................... Procontarinia Kieffer & Cecconi Oriental, 15 spp., all associated with mango, Mangifera indica (Anacardiaceae); an immigrant, P. mangiferae (Felt), known from the West Indies and Brazil, is not yet known from North America.

- Male flagellomeres bearing 1 circumfilum on proximal node, 2 on distal node. (fig. 38). Female cerci discrete (fig. 274) but may be contiguous (as for fig. 277)....................................................................... 89

89(88) Male cerci each conspicuously bilobed, hypoproct deeply incised (fig. 171). Female 8th tergite distinct, pigmented (fig. 278)..................................................................................... Lophodiplosis Gagné Australian, 5 spp, all on Melaleuca (Myrtaceae); one of them, L. trifida Gagné, introduced into Florida for biocontrol of paperbark, M. quinquenervia .

- Male cerci convex, hypoproct entire or only slightly concave apically (fig. 172). Female 8th tergite indistinct, not pigmented (fig. 279)........................................................................................... 90

90(89) Abdominal tergites with many lateral setae (as for fig. 174). Male flagellomeres with loops greatly uneven in length on basal and distal circumfila and loops of equal length on middle circumfilum (fig. 44)...................... Aphidoletes Kieffer Nearly cosmopolitan, possibly through commerce, 4 spp., all external feeders on Aphidoidea, all occurring in North America.

- Abdominal tergites without lateral setae (as for fig. 113). Male flagellomeres with circumfilar loops subequal in length (fig. 37–38) or, if greatly unequal, middle circumfilum either uneven (fig. 43) or appressed to node (fig. 47)................ 91

91(90) Claws dilated beyond bend (as for fig. 97). Gynandromorphic, with male antennae and female abdomen, its cerci cylindrical, at least four times as long as high........................................................... Tanaodiplosis Gagné Nearctic, 1 sp, T. androgynes (Felt), presumably a predator, known from one hermaphroditic specimen with male antennae and female abdomen.

- Claws not dilated beyond bend (as for fig. 93). Female cerci bilaterally flattened, ovoid, no more than twice as long as high (fig. 278)........................................................................................... 92

92(91) Male flagellomeres with loops of basal and middle circumfila greatly uneven (fig. 43). Female 9th tergum nearly bare, with only 4–6 setae (fig. 280)................................................................. Tingidoletes Gagné Nearctic, 1 sp., T. praelonga Gagné, predator of the avocado lace bug ( Heteroptera: Tingidae) in Florida.

- Male flagellomeres with circumfilar loops nearly equal in length (fig. 42). Female 9th tergum covered with many setae (fig. 279)................................................................................ Feltiella Rübsaamen Cosmopolitan, 10 spp., predators of mites, almost exclusively red spider mites (Acarina: Tetranychidae); 6 Nearctic.

93(87) Rs situated closer to R1 than to arculus (as for fig. 72). Gonocoxal mediobasal lobe and hypoproct with spinose microtrichia (fig. 177). Female cerci circular, medial surface entirely and densely covered with short setae (as for fig. 281) Youngomyia Felt Nearctic, Neotropical and Oriental, 6 spp., two of them Nearctic, one of which is widespread and inquilinous or predaceous in galls made by other gall midges, especially Schizomyia spp., on a variety of plant hosts.

- Rs or its stub appreciably closer to arculus than to end of R1 (fig. 73) or not apparent (fig. 78). Gonocoxal mediobasal lobe, if present, and hypoproct with fine microtrichia. Female cerci ellipsoid, any densely placed short setae along ventral margin, not fully covering medial surface........................................................................... 94

94(93) Abdominal tergites of 2nd through 6th segments transversely divided laterally (fig. 283)................ Karshomyia Felt Nearly cosmopolitan, 49 spp., some reared from mushrooms, others from decaying plant matter; 15 Nearctic.

- Abdominal tergites of 2nd through 6th segments entire (as for fig. 285).......................................... 95

95(94) Claws each with several teeth, pectinate (fig. 99). Male flagellomeres cylindrical, gynecoid (fig. 48)... Ctenodactylomyia Felt Neotropical, 2 spp., from hard blister galls on leaves of Coccoloba spp. ( Polygonaceae) in Florida and West Indies; 1 SE Nearctic, C. watsoni Felt.

- Claws with no more than single tooth (fig. 103). Male flagellomeres each with 2 nodes, with discrete, looped circumfila (figs 37–38)............................................................................................. 96

96(95) Male flagellomeres with 1 circumfilum on distal node (fig. 37). Females keyed elsewhere, if known................... 97

- Male flagellomeres with 2 circumfila on distal node (fig. 38). All females........................................ 98

97(96) Flagellomeres with 1 circumfilum on basal node (as for fig. 37). Gonocoxites parallel, with long, pointed, glabrous medial lobe (figs 175–176)....................................................................... Plectrodiplosis Gagné Nearctic, 1 sp., P. fascipennis Gagné, its biology unknown.

- Flagellomeres with 2 circumfila on basal node, one of them with much shorter loops than the other (fig. 45). Gonocoxites splayed, with rounded, microtrichose mediobasal lobe (fig. 180)..................... Mycodiplosis Rübsaamen (in part) Cosmopolitan, 46 spp., larvae of most species feed on rust or mildew fungi; 7 Nearctic spp. The one sp. keying to this couplet, M. rubida (Felt), is widespread in the Neotropics and has been introduced into Hawaii, but is not yet known from the Nearctic.

98(96) Male flagellomeres with middle circumfilum closely appressed to flagellomere (as for fig. 47). Female cerci with dense group of short setae medially (fig. 281)............................................................. Bremia Rondani Cosmopolitan, 21 spp., their biology mostly unknown, but one African species is predaceous on dragonfly eggs; 8 Nearctic spp.

- Male flagellomeres with middle circumfilum bearing loops (as for fig. 46). Female cerci without dense group of short setae medially............................................................................................ 99

99(98) Gonocoxite cylindrical, without mediobasal lobe (fig. 181). Ovipositor elongate, protrusible part at least four times longer than 7th tergite (as for fig. 286)................................................................. Resseliella Seitner Cosmopolitan, 55 spp., on diverse hosts, found under bark, in flower heads or simple galls; 17 Nearctic spp.

- Gonocoxite angular mediobasally or with definite mediobasal lobe (figs 178–180, 183). Ovipositor shorter, protrusible part not appreciably longer than twice length of 7th tergite.......................................................... 100

100(99) Aedeagus bifurcate or foliaceous (figs 182–185), often pigmented. Female last ventral abdominal segment with posteroventral notch (fig. 284)........................................................................................ 101

- Aedeagus cylindrical, not pigmented (figs 178–180). Female last ventral abdominal segment without posteroventral notch (as for fig. 285)........................................................................................ 102

101(100) Aedeagus foliaceous (figs 183–185), not pigmented. Female 8th tergite well delineated, pigmented... Glenodiplosis Gagné Nearctic, 1 sp., G. callipus Gagné, its biology unknown.

- Aedeagus bifurcate, often pigmented (fig. 182). Female 8th tergite undefined except for presence of vestiture................................................................................................. Coquillettomyia Felt Cosmopolitan, 42 spp, some associated with fungi or decaying vegetable matter;.4 Nearctic.

102(100) Male cerci broadly to narrowly elliptical (fig. 180). Female flagellomere necks microtrichose (as for fig. 59)...................................................................................... Mycodiplosis Rübsaamen (in part) Cosmopolitan, 46 spp., larvae of most species feed on rust or mildew fungi; 7 Nearctic spp.

- Male cerci angular, the posterior margin horizontal, oblique or concave (fig. 178). Female flagellomere necks not microtrichose (as for fig. 58)...................................................... Clinodiplosis Kieffer (in part) Cosmopolitan, 107 spp., some presumably mycophagous or secondary feeders in galls, others primary plant-feeders, some of them gall-formers; 42 Nearctic.

103(86) Claws curved or bent near basal third (fig. 100)........................................................... 104

- Claws curved or bent beyond midlength (fig. 94).......................................................... 112

104(103) Abdominal 2nd through 6th tergites transversely divided laterally (fig. 283).................................... 105

- Abdominal 2nd through 6th tergites entire (fig. 277)........................................................ 106

105(104) Aedeagus subdivided, often strongly curved; gonocoxite and/or gonostylus variously lobed (figs 188–189). Female abdomen barely protrusible, with posteroventral notch (fig. 284).................................... Karshomyia Felt (in part) Nearly cosmopolitan, 49 spp., some reared from mushrooms, others from decaying plant matter; 15 Nearctic.

- Aedeagus cylindrical, straight; gonocoxite and gonostylus without apical lobes (as for figs 178–179). Female abdomen somewhat protrusible, tapering, without posteroventral notch (as for fig. 285)............ Parallelodiplosis Rübsaamen (in part) Holarctic, Oriental, Oceanian, 19 spp., hosts unknown for most but some are inquilines with gall makers of various insect orders, others directly herbivorous; 12 Nearctic.

106(104) Rs stub closer to end of R1 than to arculus (fig. 72)........................................... Lopesia Rübsaamen Neotropical, SE Nearctic, Afrotropical, Australian, 24 spp., gall makers of many families of plants; 1 Nearctic sp., L. licaniae Gagné, from Licania michauxii (Chrysobalanaceae) in Florida.

- Rs, often barely apparent, closer to arculus than to end of R1 (fig. 74)........................................... 107

107(106) Gonocoxite bent at right angle near midlength, gonostylus strongly curved, completely glabrous, without setae on basal twothirds (figs 190–191). Female hypopharynx dentate (fig. 20).................................... Trogodiplosis Gagné Holarctic, 2 spp.; 1 Nearctic, T. flexuosa Gagné, associated with xylem vessels of fresh-cut wood.

- Gonocoxite and gonostylus straight or weakly curved, gonostylus with microtrichia basally and setae scattered throughout. Female hypopharynx with long microtrichia only (as for fig. 18).............................................. 108

108(107) Gonocoxite cylindrical or bulbous, without angular or rounded mediobasal lobe (fig. 192). Ovipositor as long as remainder of abdomen or not at all protrusible; if not protrusible, cerci abruptly decumbent ventrally at 90 degrees (fig. 287)....... 109

- Gonocoxite angular or lobed mediobasally (figs 178–179, 186). Ovipositor much shorter than abdomen and cerci not ventrally decumbent......................................................................................... 110

109(108) Aedeagus straight; hypoproct with apical setae (figs 192–193). Ovipositor as long as remainder of abdomen (fig. 286).......................................................................................... Xylodiplosis Kieffer Holarctic, Oriental, 5 spp., larvae in xylem vessels of fresh-cut wood; 1 Nearctic.

- Aedeagus recurved ventrally; hypoproct with microtrichia only. Ovipositor barely protrusible, cerci abruptly decumbent at 90 degrees (fig. 287)......................................................................... Horidiplosis Felt Oriental, 7 spp., all on Ficus (Moraceae); one sp., H. ficifolii Harris, found in Florida with imported fig plants intended for the bonsai trade.

110(108) Male cerci tapered to pointed apex; hypoproct narrower than aedeagus (fig. 186). Ovipositor with posteroventral notch (fig. 292)............................................................................ Dichodiplosis Rübsaamen Holarctic, Neotropical, 3 spp.; the one Nearctic species, D. triangularis (Felt) extends also to South America and has been reared from mushrooms and decaying organic matter.

- Male cerci with broad, convex or angular posterior margin; hypoproct appreciably wider than aedeagus (figs 178, 180). Ovipositor without posteroventral notch (fig. 285)............................................................. 111

111(110) Male cerci broadly to narrowly elliptical (fig. 180). Female flagellomere necks microtrichose (as for fig. 59)...................................................................................... Mycodiplosis Rübsaamen (in part) Cosmopolitan, 46 spp., larvae of most feed on rust or mildew fungi; 7 Nearctic.

- Male cerci concave or angular posteriorly (fig. 178). Female flagellomere necks not microtrichose (as for fig. 58)....................................................................................... Clinodiplosis Kieffer (in part) Cosmopolitan, 107 spp., some presumably mycophagous or secondary feeders in galls, others primary plant-feeders, some of them gall-formers; 42 Nearctic.

112(103) Head lacking eye facets at midheight for considerable distance, giving the appearance of 1 dorsal and 2 lateral eyes (fig. 23).................................................................................................. 113

- Head with eye facets continuous laterally or nearly so (fig. 16)................................................ 116

113(112) Abdominal 2nd through 6th tergites membranous, anterior pair of trichoid sensilla and single posterior row of setae the only vestiture. Gonostylar tooth pectinate (fig. 198)................................................ Tropidiplosis Gagné Nearctic, 1 sp., T. pectinata Gagné, presumably a predator; only ♂ known.

- Abdominal 2nd through 6th tergites sclerotized, with lateral setae and scales among other vestiture (as for fig. 174). Gonostylar tooth solid (as for fig. 197)............................................................................ 114

114(113) Palpus of 3 segments....................................................................... Adiplosis Felt Nearctic, 1 sp., A. toxicodendri (Felt), presumably a predator; only ♂ known.

- Palpus of 4 segments................................................................................. 115

115(114) Venter of male hypoproct enlarged into spinose, pigmented, coxcomb-like ventral projection (fig. 197). Female cerci cylindrical, about four times as long as high...................................................... Odontodiplosis Felt Holarctic, Oriental, 14 spp, presumably predaceous; 3 Nearctic.

- Venter of male hypoproct with or without projection; if one present, microtrichia hairlike (as for fig. 195). Female cerci elliptical in side view, about twice as long as high.................................................... Trisopsis Kieffer Cosmopolitan, 25 spp., all presumably predaceous; 4 Nearctic.

116(112) Abdominal 2nd through 6th tergites horizontally divided laterally (as for fig. 283)... Parallelodiplosis Rübsaamen (in part) Holarctic, Oriental, Oceanian, 19 spp., hosts of most unknown but some associated with gall makers of various insect orders, others directly herbivorous; 12 Nearctic.

- Abdominal 2nd through 6th tergites entire, undivided laterally (as for fig. 278)................................... 117

117(116) Females.......................................................................................... 118

- Males............................................................................................. 125

118(117) Ovipositor elongate, nearly as long to longer than abdomen; cerci tiny, dorsoventrally flattened and closely juxtaposed medially (figs 277, 294)...................................... Contarinia Rondani (in part) and Prodiplosis Felt (in part) Contarinia: Cosmopolitan, 301 spp., phytophagous, mostly gregarious in flower heads or leaf roll galls; 60 Nearctic. Not all species of this genus will key to this couplet because many lack an occipital protuberance.

Prodiplosis: Holarctic, Neotropical, 12 species, all from simple galls, a few with broad host ranges; 9 Nearctic, two of them farranging in both North and South America.

- Ovipositor short, not appreciably longer than 6th and 7th tergites combined; cerci large, separate, bilaterally flattened (fig. 279).................................................................................................. 119

119(118) Cerci with dense group of peglike apicoventral setae on venter (figs 274–275)................................. 120

- Cerci without group of closely approximated peglike setae on venter (fig. 279)................................... 121

120(119) Cerci each with no more than 10 closely set, peglike setae on venter (fig. 297)..................................................................................................... Cartodiplosis Gagné and Pectinodiplosis Felt Cartodiplosis: Nearctic, 1 sp., C. nyssaecola (Beutenmüller), a predator of a phylloxerid ( Hemiptera).

Pectinodiplosis: Nearctic and Neotropical, 1 sp., P. erratica (Felt), a predator of various insects.

- Cerci each with 25 or more ventral, closely set, peglike setae (figs 275–276)........................................................................................ Dentifibula Felt, Lestodiplosis Kieffer, and Thripsobremia Barnes Dentifibula: Cosmopolitan; 8 spp., all presumably predaceous, two known to feed on scale insects; 1 Nearctic, D. viburni (Felt) . Lestodiplosis: Cosmopolitan, 185 spp., predators of insects and mites and common inhabitants of flower heads and leafy cecidomyiid galls; 48 Nearctic spp.

Thripsobremia: Nearctic, Neotropical, 3 spp., predators of thrips (Thysanoptera) and psyllids ( Hemiptera).

121(119) R5 joining C anterior to wing apex (figs 75–76).......................................................... 122

- R5 joining C at or posterior to wing apex (figs 74, 78)....................................................... 123

122(121) R5 curved anteriorly near apex (figs 75). Ovipositor as long as 6th tergite and without definite ventral sclerite............................................................................................ Arthrocnodax Rübsaamen Cosmopolitan, 49 species, nearly all predators of Eriophyidae (Acarina), but three have been associated with other Cecidomyiidae; 4 Nearctic, two associated with eriophyids, two caught in flight.

- R5 nearly straight (fig. 76).Ovipositor much shorter than 6th tergite and with well-defined ventral sclerite (figs 298–299)........................................................................................... Endaphis Kieffer Holarctic, Oriental, 8 spp., internal parasitoids of aphids and other Hemiptera; 2 Nearctic.

123(121) Claws bent at nearly right angle, dilated beyond bend (fig. 97)................... Giardomyia Felt, Hyperdiplosis Felt Giardomyia: Holarctic, Oriental, Oceanian, a catchall category, 13 spp., 2 of them reared from plant galls but role unknown; 6 Nearctic.

Hyperdiplosis: Holarctic, Oriental, a catchall category, 11 spp.; 5 Nearctic.

- Claws gradually curved, not or weakly dilated beyond bend (fig. 94).......................................... 124

124(123) Flagellomere necks with microtrichia (fig. 49)............................................. Anthodiplosis Kieffer Holarctic, 2 spp.; 1 Nearctic, A. eutrochii Gagné, bud gall-maker on Eutrochium spp. ( Asteraceae).

- Flagellomere necks without microtrichia (as for figs 57-58) Ametrodiplosis Rübsaamen, Clinodiplosis Kieffer, Schismatodiplosis Rübsaamen, Sitodiplosis Kieffer

Ametrodiplosis: Holarctic, 20 spp. from diverse hosts of many plant families; 1 Nearctic, A. dulichii (Felt), reared from seeds of Dulichium arundinaceum (Cyperaceae) .

Clinodiplosis: Cosmopolitan, 107 spp., some presumably mycophagous or secondary feeders in galls, others primary plant-feeders, some of them gall-formers; 42 Nearctic.

Schismatodiplosis: Neotropical, 1 sp., S. lantanae (Rübsaamen), from Mexico S to Brazil, gall maker on L antana ( Verbenaceae). Sitodiplosis: Palearctic, 3 spp., one of them, S. mosellana (Géhin), an important pest of wheat introduced into North America.

125(117) Flagellomeres all gynecoid, the single node cylindrical with interconnected circumfila (as for fig. 39)................. 126

- Flagellomeres, at least on basal half of antenna, with 2 nodes and discrete circumfila (as for figs 37–38)............... 127

126(125) Hind tarsus enlarged, three times tibial diameter. Aedeagus somewhat longer than hypoproct, conspicuously recurved dorsally............................................................................... Gongrodiplosis Gagné Nearctic, 1 sp., G. latipes (Felt), female and biology unknown.

- Hind tarsus of same approximate diameter as tibia. Aedeagus approximately same length as hypoproct, straight (fig. 211)....................................................................................... Contarinia Rondani (in part) Cosmopolitan, 301 spp., phytophagous, mostly gregarious in flower heads or leaf roll galls; 60 Nearctic. Only C. fraxini (Felt) keys to this couplet.

127(125) All flagellomeres with 2 discrete circumfila (as for fig. 37)................................................. 128

- At least first 5 flagellomeres each with 3 discrete circumfila (as for fig. 38), usually all 3 with loops, but 1 may be closely appressed to flagellomere............................................................................. 136

128(127) Gonocoxites ovoid, not extended mesally or apically (as for fig. 211)......................................... 129

- Gonocoxites with angular mesal lobe or apical lobe extending beyond base of gonostylus (as for figs 202, 205, 229)..... 1 30

129(128) Scutum without scales outside bounds of medial and lateral rows of setae. Aedeagus tapered, not appreciably longer than hypoproct (Fig. 211).................................................................... Contarinia (in part) Cosmopolitan, 301 spp., phytophagous, mostly gregarious in flower heads or leaf roll galls; 60 Nearctic. Most species of this genus will key here.

- Scutum mostly covered with scales between medial and lateral rows of setae. Aedeagus cylindrical, somewhat longer than hypoproct (figs 207–208)........................................................... Endaphis Kieffer (in part) Holarctic, Oriental, 8 spp., internal parasitoids of aphids and other Hemiptera; 2 Nearctic.

130(128) Tergites with lateral setae (as for fig. 174); cerci angular at apex (as for fig. 199)................................ 131

- Tergites without lateral setae; cerci broadly rounded at apex (as for fig. 204)..................................... 133

131(130) C swollen at basal fourth to several times greater than remainder of vein.................. Ametrodiplosis Rübsaamen Holarctic, 20 spp. from diverse hosts of many plant families; 1 Nearctic, A. dulichii (Felt), reared from seeds of Dulichium arundinaceum (Cyperaceae) .

- C not swollen on basal fourth.......................................................................... 132

132(131) Flagellomere internodes and necks without microtrichia (as for fig. 50). Gonocoxites not splayed...... Sitodiplosis Kieffer Palearctic, 3 spp., one of them, S. mosellana (Géhin), an important pest of wheat introduced into North America.

- Flagellomere internodes and necks with microtrichia (49). Gonocoxites somewhat splayed (fig. 199)... Anthodiplosis Kieffer Holarctic, 2 spp.; 1 Nearctic, A. eutrochii Gagné, bud gall-maker on Eutrochium spp. ( Asteraceae).

133(130) Tergites membranous except along row of setae on posterior margin.......................................... 134

- Tergites well-sclerotized, with vestiture on posterior margin and elsewhere..................................... 135

134(133) Terminalia nearly half as long as abdomen; gonocoxal apicomedial angle elongated and thickly covered with stout setae; gonostylus tapering to pointed apex (figs 202–203)......................................... Thaumadiplosis Gagné Nearctic, 1 sp., T. magnicauda Gagné, presumably predaceous.

- Terminalia less than one-fourth as long as abdomen; gonocoxite not elongated apicomedially, the setae uniform in size; gonostylus widest apically (fig. 204).............................................................. Cordylodiplosis Gagné Nearctic, 1 sp., C. molliterga Gagné, presumably predaceous.

135(133) Gonocoxite with conspicuous, tapered apicoventral extension; gonostylus with solid apical tooth. (fig. 205)... Dentifibula Felt Cosmopolitan; 8 spp., all presumably predaceous; 1 Nearctic.

- Gonocoxite without apicoventral extension; gonostylus with broad, comblike apical tooth (fig. 206).............................................................................................. Pectinodiplosis Felt (figs 194, 206) Nearctic and Neotropical, 1 sp., P. erratica (Felt), a predator of various insects.

136(127) Gonocoxite and gonostylus articulated dorsoventrally (figs 209–210)........................ Prodiplosis Felt (in part) Holarctic, Neotropical, 12 species, all from simple galls; 9 Nearctic, two of them wide-ranging in both North and South America.

- Gonocoxite and gonostylus articulated mediolaterally (figs 207–208).......................................... 137

137(136) R5 curved anteriorly near its apex (fig. 75)............................................ Arthrocnodax Rübsaamen Cosmopolitan, 49 species, most of them known to prey on Eriophyidae (Acarina); 4 Nearctic.

- R5 straight, well-separated from C (as for fig. 76).......................................................... 138

138(137) Scutum mostly covered with scales between medial and lateral rows of setae................. Endaphis Kieffer (in part) Holarctic, Oriental, 8 spp., internal parasitoids of aphids and other Hemiptera; 2 Nearctic.

- Scutum without scales outside bounds of medial and lateral rows of setae....................................... 139

139(138) First through fifth flagellomeres each with 3 circumfila, the middle one appressed to flagellomere and without loops (fig. 47); 6th to 12th flagellomeres with only 2 circumfila, the middle one lost................. Thripsobremia Gagné (in part) New World, 3 spp., predators of thrips (Thysanoptera) and psyllids ( Hemiptera); 2 Nearctic.

- All flagellomeres with 3 circumfila, each with loops (as for fig. 46)............................................ 140

140(139) Gonocoxite with prominent, narrow, dorsoapical extension (fig. 212)............................... Epidiplosis Felt Holarctic, Oriental, 14 spp., one a predator of coccoids ( Hemiptera), the remainder caught in flight, including the one Nearctic sp., E. sayi Felt.

- Gonocoxite without conspicuous dorsoapical extension (fig. 212)............................................. 141

141(140) Aedeagus pigmented, dorsoventrally flattened, serrate laterally and as wide as combined cerci (figs 213–215)................................................................................................. Platydiplosis Gagné Nearctic, 1 sp., nigricauda Gagné, biology unknown.

- Aedeagus not pigmented, cylindrical, not serrate, no wider than one cercus (fig. 204)................................ 142

142(141)R5 vein ending near wing apex, at most slightly curved (fig. 77).............................................. 143

- R5 vein ending posterior to wing apex, curved apically (fig. 78)............................................... 144

143(142) Hypoproct divided and splayed apically, appreciably wider than aedeagus (fig. 216)........ Cartodiplosis Gagné (in part) Nearctic, 1 sp., C. nyssaecola (Beutenmüller), a predator of a phylloxerid ( Hemiptera).

- Hypoproct parallel-sided, convex apically, not much wider than aedeagus (figs 194–196)...... Lestodiplosis Kieffer (in part) Cosmopolitan, 185 spp., predators of insects and mites and common inhabitants of flower heads and leafy cecidomyiid galls; 48 Nearctic spp.

144(142) Claws gently curved (as for fig. 94).................................................................... 145

- Claws strongly bent, forming almost a right angle (fig. 97)................................................... 146

145(144) Cerci convex apically (fig. 211)................................................... Contarinia Rondani (in part) Cosmopolitan, 301 spp., phytophagous, mostly gregarious in flower heads or leaf roll galls; 60 Nearctic. Only Contarinia catalpae (Comstock) will key here; all others have one circumfilum on each node of the flagellomeres.

- Cerci angled, concave on apical margin (fig. 229)..................................... Schismatodiplosis Rübsaamen Neotropical, 1 sp., S. lantanae (Rübsaamen), from Mexico S to Brazil, gall maker on Lantana (Verbenaceae) .

146(144) Hypoproct simple, convex apically or deeply lobed, resulting lobes long, pointed, and splayed (fig. 217)...................................................................................................... Hyperdiplosis Felt Holarctic, Oriental, a catchall category, 11 spp.; 5 Nearctic.

- Hypoproct narrow apically, triangularly emarginate (fig. 218)...................................... Giardomyia Felt Holarctic, Oriental, Oceanian, a catchall category, 13 spp., 2 of them reared from plant galls but role unknown; 6 Nearctic.

147(85) C not interrupted immediately posterior to juncture with R5 (fig. 79); if condition unclear, proceed as if C is not interrupted.................................................................................................... 148

- C interrupted beyond juncture with R5 (as for fig. 75)....................................................... 160 148(147) Rs stub closer to end of R1 than to arculus (fig. 79)....................................................... 149

- Rs stub closer to arculus than to end of R1 (as for fig. 73), or stub not apparent (fig. 78)............................ 152

149(148) Thorax produced anteriorly over the head. Claws broadly curved, empodia diminutive (fig. 101)..... Planetella Westwood Holarctic, 52 spp., the reared species associated with Carex (Cyperaceae); 23 Nearctic.

- Thorax not produced anteriorly over the head. Claws curved beyond midlength, empodia reaching bend in claws (fig. 94)...................................................................................................... 150

150(149) Tergites without scales or lateral setae (fig. 293). Male hypoproct expanded ventrally to bracket aedeagus (figs 219–220). Female flagellomeres with 3 interconnected circumfila (fig. 61). Female cerci with about 5 long, peglike setae apically (fig. 293)............................................................................... Vaccinidiplosis Gagné Nearctic, 1 sp., from leaf galls on Vaccinium spp. ( Ericaceae).

- Tergites with lateral setae and some scales in addition to posterior setae. Male hypoproct flat, not expanded ventrally (113–114). Female flagellomeres with 2 interconnected or 3 discrete circumfila. Female cerci with about 30 closely set, short, peglike setae ventrally................................................................................ 151

151(150) Palpus of 3 segments. Frons without setae. Female flagellomeres with 3 discrete horizontal circumfila. Aedeagus stout, bulbous apically (figs 222–223)............................................................ Blaesodiplosis Gagné Nearctic, 4 spp., from leaf galls on Amelanchier, Crataegus and Rosa ( Rosaceae).

- Palpus of 4 segments. Frons with setae. Female flagellomeres with 2 interconnected horizontal circumfila. Aedeagus tapered to narrow apex (fig. 221).................................................................... Putoniella Kieffer Holarctic, 2 spp., on Prunus (Rosaceae); 1 Nearctic, P. gracilis Gagné on leaves of Prunus (Rosaceae) .

152(148) Palpus of 1–2 segments............................................................................. 153

- Palpus of 3–4 segments............................................................................... 155

153(152) Claws strongly and evenly tapered from base to apex (fig. 102). Female cerci fused, cultriform, stiff and glabrous (fig. 289)............................................................................. Monarthropalpus Rübsaamen Palearctic, 1 sp., M. flavus (Schrank), accidentally introduced into North America with its host Buxus sempervirens (Buxaceae) .

- Claws weakly tapered (as for fig. 94). Female cerci discrete, flexible, setose and microtrichose (fig. 288).............. 154

154(153) Tergites with lateral setae, scales or both (as for fig. 296). Surface of protrusible part of ovipositor obscured by long white setae................................................................................ Halodiplosis Kieffer Holarctic, 99 spp, all bud gall formers on Chenopodiaceae; 1 W Nearctic, sp., H. sarcobati (Felt) .

- Tergites without scales and lateral setae (fig. 288). Protrusible part of ovipositor with scattered short setae only, dorsal surface with obvious dorsal, narrow sclerite (fig. 288)............................................ Caryomyia Felt (in part) E Nearctic, 56 spp., all from complex leaf galls on Carya (Juglandaceae) . Only C. spherica keys to this couplet.

155(152) Tergites without scales and lateral setae (fig. 288)........................................................ 156

- Tergites with lateral setae or scales or both (as for fig. 285)................................................... 157

156(155) Sternites with anterior pair of trichoid sensilla (as for fig. 293)................................ Apagodiplosis Gagné Nearctic, 1 sp., A. papyriferae (Gagné), from buds of Betula papyrifera (Betulaceae) .

- Sternites without anterior trichoid sensilla (as for fig. 288).................................. Caryomyia Felt (in part) E Nearctic; 56 spp., all from complex leaf galls on Carya (Juglandaceae) .

157(155) Abdominal tergites without scales. Protrusible part of ovipositor more than four times as long as 7th tergite.................................................................................................... Paradiplosis Felt Holarctic, 4 spp., in galls on needles of Abies and Picea (Pinaceae); 2 Nearctic.

- Abdominal tergites with scales (as for fig. 285). Protrusible part of ovipositor less than twice as long as 7th tergite....... 158

158(157) Gonostylar tooth narrow, pointed (figs 224–225). Female flagellomeres with 3 circumfila............. Pilodiplosis Gagné Nearctic, 1 sp., P. helianthibulla (Walsh), leaf gall maker on Helianthus (Asteraceae) .

- Gonostylar tooth broad, comblike (as for fig. 223). Female flagellomeres with 2 circumfila......................... 159

159(158) Male flagellomeres with 2 circumfila (as for 37). Protrusible part of ovipositor without dorsal sclerite.. Lobopteromyia Felt E Nearctic, 1 sp., host unknown.

- Male flagellomeres with 3 circumfila (as for fig. 38). Protrusible part of ovipositor with dorsal sclerite (as for fig. 288).......................................................................................... Caryadiplosis Gagné E Nearctic, 2 spp. in simple leaf galls on hickories, Carya (Juglandaceae) .

160(147) Palpus of 1–2 segments............................................................................. 161

- Palpus of 3–4 segments............................................................................... 163

161(160) Abdominal terga without lateral setae.................................................... Stenodiplosis Reuter Cosmopolitan, 11 spp., all in florets of grasses ( Poaceae); 5 Nearctic, 3 of them introduced from Eurasia or Africa.

- Abdominal terga with lateral setae (as for fig. 174)......................................................... 162

162(161) Male flagellomeres with 2 circumfila. Female flagellomeres with 2 interconnected, looped circumfila. Protrusible part of ovipositor short, barely longer than 6th tergite, cerci tapering to a point (figs 290–291)................... Pinyonia Gagné W Nearctic, 1 sp., P. edulicola, on Pinus edulis (Pinaceae) .

- Male flagellomeres with 3 circumfila. Female flagellomeres with several interconnected, appressed circumfila. Protrusible part of ovipositor several times longer than 6th tergite, the cerci rounded at apex (as for fig. 286............ Olpodiplosis Gagné Nearctic, 1. sp., O. helianthi (Brodie), on Helianthus spp. ( Asteraceae).

163 (160) Claws, at least those of foretarsus, with basal tooth....................................................... 164

- Claws without basal tooth............................................................................. 167

164(163) Claws evenly bowed or curved beyond midlength (fig. 94)................................................. 165

- Claws bent near basal third (fig. 100).................................................................... 166 165(164) Gonocoxites somewhat splayed, with mediobasal lobe (fig. 226). Ovipositor barely protrusible...... Dicrodiplosis Kieffer Cosmopolitan, 12 spp., the 7 spp. with known hosts are predators of Coccoidea; 4 Nearctic.

- Gonocoxites parallel, without mediobasal lobe (fig. 227). Ovipositor elongate-protrusible (fig. 301)................................................................................................ Harmandiola Skuhravá (in part) Holarctic, 14 spp., from galls on Populus (Salicaceae), Castanea (Fagaceae) and Carya (Juglandaceae); 6 Nearctic.

166(164) Occiput without prominent dorsal pair of setae. Eye facets farther apart at midheight than elsewhere (fig. 21). Rs not apparent (fig. 78).............................................................................. Diadiplosis Felt Cosmopolitan, chiefly tropical, 32 spp., their larvae predaceous on whiteflies and scale insects, chiefly Pseudococcidae (Hemiptera); 6 Nearctic.

- Occiput with prominent dorsal pair of setae. Eye facets uniformly close (as for fig. 22). Rs present as stub (as for fig. 72).......................................................................................... Pitydiplosis Gagné Holarctic, 2 spp.; 1 Nearctic, P. packardi (Felt) associated with Pinus strobus (Pinaceae) .

167(163) Rs stub closer to end of R1 than to arculus (as for fig. 72). Gonostylus longer than gonocoxite......... Obolodiplosis Felt Nearctic, 1 sp., O. robiniae (Haldeman) in leaf galls of Robinia (Fabaceae) . This species was accidentally introduced into Eurasia where it is now widespread.

- Rs stub closer to arculus than to end of R1 (as for fig. 79) or not apparent. Gonostylus appreciably shorter than gonocoxite..................................................................................................... 168

168(167) Claws bowed near basal third (fig. 98)................................................................. 169

- Claws strongly bowed beyond midlength (fig. 94)......................................................... 171

169(168) Occiput with 2 exceptionally large setae (indicated by large sockets if setae lost) immediately behind eyes. Abdominal tergites with only the posterior marginal setae and pair of anterior trichoid sensilla as vestiture............ Silvestriola Skuhravá Cosmopolitan, 14 spp., presumably all predaceous; 1 Nearctic, S. cincta (Felt), a widespread predator of various insects and mites.

- Occiput without pair of exceptionally large setae (or sockets) immediately behind eyes. Abdominal tergites with lateral setae and scales in addition to posterior setae and pair of anterior trichoid sensilla (as for fig. 285)........................ 170

170(169) Eye bridge about 5 facets long. Female cerci fused (as for fig. 272–273). Male flagellomeres with 2 or 3 circumfila............................................................................................ Taxodiomyia Gagné E Nearctic, 3 spp., several more undescribed, all from leaf galls on Taxodium (Taxodiaceae) .

- Eye bridge about 10 facets long. Female cerci discrete. Male flagellomeres with 3 circumfila........... Sequoiomyia Möhn Holarctic, 2 spp., one a European fossil in Sequoia cones, the other a Nearctic sp., S. taxodii (Felt) in cones of Taxodium distichum (Taxodiaceae) .

171(168) First and second flagellomeres separate, not fused (fig. 51)............................. Cecidomyia Meigen (in part) Holarctic, 19 spp., all associated with resin of Coniferae; 10 Nearctic.

- First and second flagellomeres fused (fig. 52)............................................................. 172

172(171) Gonocoxite and gonostylus articulated dorsoventrally (figs 209–210). Females keyed elsewhere ... Prodiplosis Felt (in part) Holarctic, Neotropical, 12 species, all from simple bud or flower galls; 9 Nearctic, of which only the male of P. falcata Gagné runs to this couplet.

- Gonocoxite and gonostylus articulated lateromedially (fig. 210). All females.................................... 173

173(172) Palpus of 3 segments, the third joined subapically to second.................................. Zeuxidiplosis Kieffer Palearctic, 1 sp., Z giardi (Kieffer), introduced into California and elsewhere for control of Hypericum perforatum (Hypericaceae) .

- Palpus of 4 segments, disposed end to end................................................................ 174

174(173) Male flagellomeres with 2 circumfila. Female cerci closely juxtaposed, dorsoventrally flattened (figs 277, 294–295)... 175

- Male flagellomeres with 3 circumfila. Female cerci well-separated, not dorsoventrally flattened (fig. 296)............. 177

175(174) Abdominal tergites without lateral setae.................................................. Stenodiplosis Reuter Cosmopolitan, 11 spp., all in florets of grasses, 5 Nearctic, 3 of them introduced from Eurasia or Africa.

- Abdominal tergites with lateral setae (as for fig. 296)........................................................................................ Chamaediplosis Gagné (in part), Contarinia Rondani (in part), Prodiplosis Felt (in part) Chamaediposis: W Nearctic, 2 spp. forming galls on shoot tips of Cupressus spp. ( Cupressaceae). Males are not distinguishable from Contarinia; females key to genus at another couplet.

Contarinia: Cosmopolitan, 301 spp., phytophagous, mostly gregarious in flower heads or leaf roll galls; 60 Nearctic. Most species of this genus will come out at this point.

Prodiplosis: Holarctic, Neotropical, 12 species, all from simple galls; 9 Nearctic, of which only the female of P. falcata Gagné runs to this couplet.

176(174) Female cerci tapering evenly to apex, triangular; hypoproct bilobed (fig. 296)........... Chamaediplosis Gagné (in part) W Nearctic, 2 spp. forming galls on shoot tips of Cupressus spp. ( Cupressaceae). Only the females key here; males are not distinguishable from Contarinia .

- Female cerci rounded at apex, ovoid; hypoproct not divided apically (fig. 301)................................... 177

177(176) Male circumfilar loops uneven in length. Aedeagus evenly cylindrical, broadly rounded apically (Fig. 227). Female ninth segment without dorsal sclerite (fig. 301).......................................... Harmandiola Skuhravá (in part) Holarctic, 14 spp., from galls on Populus (Salicaceae), Castanea (Fagaceae) and Carya (Juglandaceae); 6 Nearctic.

- Male circumfilar loops of equal length. Aedeagus tapered from base to narrow apex (fig. 228). Female ninth segment with dorsal sclerite on apical third (as for fig. 288)................................................. Macrodiplosis Kieffer Holarctic, 13 spp., all leaf gall makers on leaves of Quercus (Fagaceae); 9 Nearctic.