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Keys to the Families & Subfamilies of Nearctic Chalcidoidea

 

(Derived fr. Grissell & Schauff 1990 by E. F. Legner)

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[This key is in a form commonly used in North America.    If the statement is true accept the information shown, and proceed to linked couplet if present for additional information.  If statement is false, go to "b" portion of the couplet].

 

       Chalcidoidea is a large Superfamily of important insects that have been deployed successfully in biological control worldwide.  Specialists generally agree to being aware of only a fraction of those still awaiting discovery.  Their taxonomy is often difficult as the characters used may show wide variation.  Most species are small or very tiny, some being less than 0.4 mm in long.  Chalcids occur almost everywhere, but because of their small size they are usually overlooked.  Adults occur mainly on flowers and plant foliage.  Most species are parasitoids of other insects, attacking the egg or larval stage of their hosts. Predominant hosts are Lepidoptera, Diptera, Coleoptera, and Homoptera.  Because these host groups contain many agricultural pests, it is obvious that the chalcids are a valuable group for natural control. Many species have been imported into different countries for biological control.  The larvae of  few species are phytophagous.

 

[Also illustrations may be found in <Guide> (Powerful connections use <Guide-2>)]

 

 

 

2

 1a.    Hind femur enlarged, with ventral teeth, either a few large or many small ones (saw-like); hind  tibia subequal to femur and arched; specimens usually 5-15 mm, stout bodied, rarely <1-2 mm

6

 

 1b.    Hind femur not enlarged, ventral denticles, if present, 2 or less, or ventral edge serrate; hind tibia straight (rarely half length of femur); specimens usually 1-10 mm., stout to fragile

 

3

  2a.    Prepectus reduced or fused, not readily apparent, of if so, not triangular in outline

 

5

 2b.    Prepectus apparent as a triangular plate

 

4

  3a.    Ovipositor directed horizontally [in most species not extended beyond apex of metasoma

     (gaster)]; tegula almost an oval disc; fore wing not folded longitudinally.      Chacididae

     <Habits>; <Adults> & <Juveniles>

 

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 3b.    Ovipositor curved dorsally over metasoma (gaster); tegula narrowly extended forward; fore

      wing  often folded longitudinally.     Leucospidae   <Habits>; <Adults> & <Juveniles>

 

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  4a.    Frons projects as 2 "horns" (surrounding antennae) in dorsal view      Chalcididae

             (Dirhininae)   

 

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  4b.    Frons not modified as "horns," mostly flat in dorsal view; hind tibia squarely truncate at apex; 2 hind tibial spurs          Chalcididae       (Haltichellinae)

 

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  4c.    Frons not modified as "horns," mostly flat in dorsal view; hind tibia obliquely truncate at

      apex; either 1 hind tibial spur or spur not apparent.      Chalcididae       (Chalcidinae)

 

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  5a.   Eyes diverge ventrally; antennae inserted low on face; ovipositor not exserted         Pteromalidae    (Chalcedectini:   Cleonyminae)  (part)  <Habits>; <Adults> & <Juveniles>

 

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   5b.    Eyes nearly parallel; antennae inserted near middle of face; ovipositor exserted 

     Torymidae  <Habits>; <Adults> & <Juveniles>   (Podagrionini:  Monodontomerinae)  (part)

 

7

  6a.    Antennae with 5-7 segments between pedicel and club; tarsi usually with 5 segments (if with 4, then males of  Tetracampidae (<Habits>; <Adults> & <Juveniles>),  or tiny specimens with long antennae & characteristic wings, (see Mymaridae  <Habits>; <Adults> & Juveniles>) 

 

40

6b.  Antennae with 0-4 segments between pedicel and club; tarsi with 3, 4, or 5 segments; or  specimens 0.2-1 or 2 mm. long and such characters hard to see (many tiny fragile specimens)

 

9

7a.  Hind wing without stalk, expanded as shown; forewing venation ends beyond basal 1/3rd (postmarginal present, stigmal elongated to sessile); specimens usually >2 mm.

 

8

7b.    Hind wing stalked and elongated (rarely reduced to only a short stub, hooked at tip); fore wing venation linear, ending in basal 1/3rd (postmarginal absent, stigmal rudimentary), or apparently absent; specimens usually <2 mm.   

 

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   8a.    Abdominal petiole with 2 segments; fore wing reticulate (rare in North American collections)

           Mymarommatidae     <Habits>; <Adults> &  <Juveniles>

 

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8b.    Abdominal petiole with 1 segment or none; fore wing membrane smooth (common in North American collections)      Mymaridae   <Habits>; <Adults> & <Juveniles>

 

10

   9a.    Mesopleuron concave; midtibial spur thin and like a spine.

 

36

   9b.    Mesopleuron convex (bulging); midtibial spur relatively thick.

 

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10a.    Head projects forward, female mandible with rasplike appendage; at least hind tibia shorter than femur; male wingless (much modified); collected from fig fruits Agaonidae      <Habits>; <Adults> & <Juveniles>

 

11

10b.    Head projects downward, female without appendage on mandible; hind tibia at least as long as femur, usually longer; male similar to female

 

13

11a.    Antennal insertion definitely more than one torulus diameter above free margin of clypeus; if doubtful, then  either eyes diverge ventrally or side of head ("cheeks") carinate

 

12

11b.    Antennal insertion less than one torulus diameter above free margin of clypeus; if doubtful, side of head without carinae

 

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12a.    Antennae arise at side and below free margin of clypeus; abdominal petiole longer than wide (common in North American collections)..... Pteromalidae     (Spalangiinae)

     <Habits>; <Adults> & <Juveniles>

 

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12b.    Antennae arise slightly above free margin of clypeus; abdominal petiole not visible (rare in North American collections)....... Pteromalidae (Ceinae)  [also see Asaphinae & Eunotinae]. <Habits>; <Adults> & <Juveniles>

 

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  13a.    Fore wing stigma enlarged, longer than stigmal vein, and projects toward hind margin of

        wing; ovipositor sheaths always exserted; antennae with 7 funicle segments  Torymidae

       (Megastigminae).

 

14

13b.    Fore wing stigma not enlarged, shorter than stigmal vein (stigma at times surrounded by pigmented stainlike area); ovipositor and antenna variable

 

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14a.    Scutellum with submedian grooves that meet prescutal sutures and delimit media rectangular area (ra) or stigmal vein long and almost at right angle to marginal vein (rare in collections from fig fruits in Florida)       Torymidae    (Sycophaginae)

 

15

14b.    Scutellum without submedian grooves, prescutal sutures separated from scutellum by axilla (ax); either stigmal vein ling and angled off of marginal vein or short (common & widespread in North America)

 

16

15a.    Hind coxa much longer and winder than forecoxa by 2-3 times; if doubtful, then prescutal sutures absent or weak and female with exserted ovipositor.

 

18

15b.    Hind coxa nearly same size as fore coxa; if doubtful, then prescutal sutures well developed and female ovipositor not exserted.

 

17

16a.    Ovipositor definitely exserted; both sexes: abdomen without pits; propodeum postero-laterally angled and does not project over hind coxa (dorsal view); cerci of last tergum elongated and with long setae (not as apparent in male as female); prepectus subequal to tegula; hind tibial spurs thin.     Torymidae   ...   (Subfamilies:

 

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16b.    Ovipositor not exserted; both sexes:  abdomen with pits; propodeum postero-laterally rounded and projects over hind coxa (dorsal view); cerci of last tergum like a disk; prepectus much smaller than tegula; hind tibial spurs thickened. ........... Ormyridae    <Habits>; <Adults> & <Juveniles>

 

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   17a.    Metapleuron with straight anterior margin............ Torymidae  (Monodontomerinae)

 

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   17b.    Metapleuron with anterior margin angulate or protruding forward ............ Torymidae 

                   (Toryminae)

 

19

18a.    Pronotum rectangular in dorsal view, about as wide as scutum, sides parallel and flat laterally; body black, yellow, or mixed black & yellow, but rarely faintly metallic; abdomen usually oval in crossview and compressed laterally ...... Eurytomidae.   <Habits>; <Adults> & <Juveniles> 

      (Subfamilies:   19)

 

1

18b.    Pronotum in dorsal view narrowed to a transverse strip, or not visible (if elongated, then narrower at base than apex and sides concave to accomodate front femora (rare, some Cleonyminae); body often metallic blue or green, rarely black; abdomen usually keel-shaped (triangular in cross view) and somewhat compressed dorsally.

 

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   19a.    Prepectus (p) as large or larger than tegula.      Eurytomidae       (Eurytominae)

 

20

   19b.    Prepectus smaller than tegula.

 

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   20a.    Scutellum with projection; tegula sculptured.      Eurytomidae      (Heimbrinae)

 

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   20b.    Scutellum without projection; tegula smooth.     Eurytomidae      (Rileyinae)

 

22

21a.    Pronotum not visible in dorsal view, covered by distinctly arched scutum; abdomen like a rudder, on long petiole ....  Eucharitidae.   <Habits>; <Adults> &  <Juveniles>..(Subfamilies:   22)

 

23

21b.    Pronotum visible in dorsal view, scutum not heavily arched; abdomen usually elongated and petiole usually not visible (petiolate forms occur).

 

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   22a.    Prepectus fused to pronotum.      Eucharitidae      (Eucharitinae)

 

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     22b.    Prepectus not fused to pronotum.      Eucharitidae      (Oraseminae)

 

24

23a.    Abdomen covered by first two terga (or seemingly covered by single tergum); body short

and squat; head with well-defined clypeus and at least 1 mandible with 2 teeth .    Perilampidae

      <Habits>; <Adults> & <Juveniles>       (Subfamilies:   24)

 

25

23b.    Abdomen with 3 or more readily visible terga; body usually elongated; head variable but usually with inconspicuous clypeus and small mandibles with 3-4 teeth      Pteromalidae

       Habits>; <Adults> & <Juveniles>     (Subfamilies:   25)

 

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     24a.    Prepectus not fused to pronotum; suture clearly visible....   Perilampidae

                   (Chrysolampinae)

 

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     24b.    Prepectus fused to pronotum (suture absent or faint) ........ . Perilampidae

                  (Perilampinae)

 

26

     25a.    Axillae (ax) advanced far forward of scutellum or cuts a distinct angle into side lobe of

                  scutum.

 

28

 25b.    Axillae not extended forward of scutellum, or if slightly advanced, does not cut a distinct angle into side lobe of scutum.

 

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 26a.    Axillae enlarged, nearly meeting medially; body covered with white, scale-like setae

           Pteromalidae     (Eutrichosomatinae)     <Habits>; <Adults> & <Juveniles>

 

27

     26b.    Axillae not enlarged, not close medially; body without white, scale-like seta.

 

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 27a.    Scutellum posterior without triangular "projection" and with parallel dorsal grooves

          Pteromalidae     (Colotrechninae)     <Habits>; <Adults> & <Juveniles>

 

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 27b.    Scutellum posterior with triangular "projection" (is part of metanotum) and without apparent dorsal grooves...... Pteromalidae     (Macromesinae)     Habits>; <Adults> & <Juveniles>

 

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    28a.    Head in dorsal view with posterior ocelli touching sharp occipital edge      Pteromalidae 

                 (Eunotinae)     <Habits>; <Adults> & <Juveniles>

 

9

28b.    Head in dorsal view with posterior ocelli distant from rounded occipital margin; if doubtful, then head with curved black spines.

 

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29a.    Head with projection between antennae, visible both from above and side (antennae notshown)    Pteromalidae  (Cerocephalinae)     <Habits>; <Adults> & <Juveniles>

 

30

   29b.    Head without interantennal projection.

 

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30a.    Head and thorax dorsally with black, curved spines; hind coxae with find transverse

      carinae       Pteromalidae      (Diparinae)     <Habits>; <Adults> & <Juveniles>

 

31

30b.    Head and thorax may have setae, but not black spines; hind coxae sculptured or smooth, without transverse carinae

 

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31a.    Body typically elongated (1-2 cm.); head with ridged, raised areas between eye and scrobal basin.  (Very rare in North America).      Pteromalidae      (Leptofoeninae)

 

32

31b.    Body less elongated (usually less than 1 cm.); head without ridged, raised area between eye and scrobal basin (commonly collected in North America)

 

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32a.    Eyes divergent ventrally, parallel dorsally; pronotum often, though not always, longer than wide         Pteromalidae       (Cleonyminae)       <Habits>; <Adults> & <Juveniles>

 

33

   32b.    Eye margins mostly parallel; pronotum always wider than long.

 

34

33a.    Either eyes, head, and thorax densely covered with setae, or scutellum largely polished and with only 2 pairs of bristles (rare in North American collections) 

 

35

33b.    Eyes not densely covered with setae, head and thorax occasionally so; scutellum rarely with paired bristles, but if so there are 3 or more pairs and they are inconspicuous.

 

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    34a.    Eyes, head and thorax densely covered with setae,     Pteromalidae     (Herbertinae)

                 <Habits>; <Adults> & <Juveniles>

 

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34b.    Eyes not covered with setae; scutellum largely polished and with 2 pairs of prominent

 bristles,        Tetracampidae     <Habits>; <Adults> & <Juveniles>

 

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   35a.    Sides of head ("cheeks") laterally carinate.       Pteromalidae      (Asaphinae)

                 <Habits>; <Adults> & <Juveniles>

 

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   35b.    Sides of head rounded laterally.      Pteromalidae      (Pteromalinae / 

                Miscogasterinae)     <Habits>; <Adults> & <Juveniles>

 

37

36a.    Cercus at apex of gaster; fore and midcoxae separated (midcoxa posterior to midpoint of mesopleuron); axillae (ax) do not meet medially (if so, at least as long as wide); marginal vein longer than stigmal or postmarginal.

 

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36b.    Cercus anterior to apex of gaster; fore & mid coxae nearly touching (mid coxa anterior to middle of mesopleuron); axillae (ax) meet medially; marginal vein usually shorter than stigmal or postmarginal.     Encyrtidae     <Habits>; <Adults-1> & <Adults-2>; &  <Juveniles>

 

38

    37a.    Prescutal sutures rarely visible, do not meet; prepectus flat, not projected     Eupelmidae

              <Habits>; <Adults> & <Juveniles>     (Subfamilies:   38)

 

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    37b.    Prescutal sutures meet medially; prepectus inflated and projected forward.

                        Tanaostigmatidae     <Habits>; <Adults> & <Juveniles>

 

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    38a.    Lack membranous area anterior to mid coxal insertion.     Eupelmidae

                     (Metapelmatinae)

 

39

    38b.    With membranous area (m) anterior to midcoxal insertion

 

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    39a.    Scutum wider than pronotum, with anterolateral shoulders produced.      Eupelmidae

                 (Calosotinae)

 

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    39b.    Scutum not much wider than pronotum, with anterolateral shoulders indistinct .... 

                   Eupelmidae       (Eupelminae)

 

41

40a.    Usually 1 mm. or longer; body often metallic or dark in color; abdomen narrowly joined at propodeum (petiole may or may not be apparent); tarsi always with 4 segments; postmarginal vein present or absent.

 

45

40b.    Usually 1 mm or less in length; body mostly pale yellow to white, sometimes with dark markings or wholly dark, but not metallic; abdomen broadly joined to propodeum; postmarginal vein absent; tarsi usually with 3-5 segments (if 4 segments, then club large and undivided or wing fringed with long setae, or middle tarsi with only 4 segments).

 

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41a.    Hind coxa greatly enlarged; posterior scutellum with triangular, usually translucent flap overhanging propodeum; hind tibia with irregular, linear, or diamond-shaped patterns of setae; habitus as shown. .......  Elasmidae     <Habits>; <Adults> & <Juveniles>

 

42

41b.    Hind coxa not greatly enlarged (normal); posterior scutellum without overhanging triangular flap; hind tibia without irregular setal patterns ... Eulophidae     <Habits>; <Adults> &

<Juveniles>     (Subfamilies: 42  )

 

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42a.    Scutellum with 1 pair of setae; submarginal vein with 2 setae; face usually with scrobal and facial grooves.       Eulophidae      (Entedoninae)

 

43

42b.    Scutellum with 2 pairs of setae (rarely 3 or more); submarginal with 3 or more setae (rarely with 1 or 2); face usually without distinct grooves

 

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43a.    Fore wing with bare area posterior to marginal vein with single row of setae; usually with 2-3  "lines of setae" radiating from stigmal vein.       Eulophidae      (Euderinae)

 

44

43b.    Fore wing usually evenly setose posterior to marginal vein without row of setae; rarely with any "lines of setae" radiating from stigmal, when present, usually only

 

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44a.    Postmarginal vein usually absent; scutellum often with paired submedian grooves that divide the scutellum  into 3 distinct pieces.       Eulophidae      (Tetrastichinae)

 

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44b.    Postmarginal vein present; scutellum without submedian grooves, rarely with lateral grooves, when present at extreme lateral margins.      Eulophidae      (Eulophinae)

 

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45a.    Tarsi with 3 segments; setae on wings usually arranged in rows; stigmal vein usually

elongated; antennae short and with few discernible funiculars, male with elongated antennal

     "setae.".          Trichogrammatidae     <Habits>; <Adults> & <Juveniles>

 

46

45b.    Tarsi with 4-5 segments; setae on wings largely absent, evenly covering wings, orwith only a few bare spots or rows present; stigmal vein short and not obviously divergent from wing margin; antennae variable, but usually with discernible funicles (if not, then with large undivided club)

 

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46a.    Propodeum without median triangular area; scutellum (sc) not transverse (anterior, posterior sides not parallel), axillae (ax) distinct from scutellum, rarely meeting medially; club of antenna almost always segmented (a few species here have antennae like Signiphordae).  Axillae (ax) do not meet medially, generally widely separated; prescutal sutures (n) present; (antennal club in Eretmocerus large and undivided, tarsi with 4 segments).     Aphelinidae     <Habits>; <Adults> & <Juveniles>

 

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46b.    Propodeum with triangular median area (ma); scutellum (sc) transverse (sides parallel), axillae either united with scutellum or widely separated; club of antenna elongated and not

segmented        Signiphoridae     <Habits>; <Adults> & <Juveniles>

 

REFERENCES:

 

Grissell, E. E. & M. E. Schauff.  1990.  A Handbook of the Families of Nearctic Chalcidoidea (Hymenoptera).

     Publ. Ent. Soc. Wash..  Cushing-Malloy, Ann Arbor, MI.  85 p.