Practical Key to Family Group Taxa Based on Females

Because the key to families (Sec. 33) depends heavily on characters that are difficult to see in dry specimens with the mouthparts in repose, a key based on more readily observable characters seems worthwhile. This key does not usually lead to families, but rather directs the user to tribes or subfamilies. It is based on females; for males, it is best to make the necessary examinations of mouthparts and use the key to families, Section 33.

The tibial hairs of Pararhophites (Megachilidae) look like a scopa but may not function for pollen carrying. For the purposes of this key, they are considered to be a scopa (see couplet 1).

Users of the key will find that both Xylocopinae and Apinae run to Apidae, couplet 11. See Section 85 for distinctions between the two.

Ancyla (Ancylini) and the Ctenoplectrini are apids that would run to Melittidae (couplet 11) on the basis of the palpal character. Ancyla, from xeric palearctic areas, is a genus of nondescript small anthophoriform bees hard to characterize without examination of the mouthparts. The Ctenoplectrini, from paleotropical and oriental areas, are easily recognized in the female by the broad, finely comblike inner hind tibial spur and the long oil-collecting hairs on the metasomal sterna, the hairs reduced but nonetheless evident in the parasitic genus Ctenoplectrina.

The specification "cleptoparasites and social parasites within Apinae" in couplet 23 means the tribes Ericro-cidini, Isepeolini, Melectini, Osirini, Protepeolini, Rha-thymini, and parts of Tetrapediini, Euglossini, and Bombini. See the key in Section 85.

Key to the Family-Group Taxa of Bees, Based on Adult Females

1. Scopa, consisting of hairs for carrying pollen, present

2(1). Scopa consisting of erect branched hairs, longest on S2, shorter on S1 and S3 (Fig. 46-1b), scopal hairs often present also on hind legs [body hylaeiform; submarginal cells two, second much smaller than first (Fig. 46-1)]

neotropics) Xeromelissinae (Colletidae) (Sec. 46)

—. Scopa variable, but hairs not erect, not longest, and branched on S2 3

3(2). Scopa well developed on metasomal sterna (Fig. 8-7b) but absent on hind legs [submarginal cells two, usually about equal in length (Figs. 76-1a, 80-1, 81-1, 82-1, 832, 84-1), except three in Fideliini, which have long hairs on hind legs that are not used in carrying pollen]

Megachilidae (Sec. 75)

—. Scopa on hind legs (Figs. 6-4, 8-5b, 10-11a), sometimes also on sterna 4

4(3). Scopa (sometimes as a tibial corbicula) on hind tibia and usually basitarsus, elsewhere not well developed, tibial scopa thus looking considerably larger than that of femur (Figs. 6-4, 10-11a) 5

—. Scopa on hind femur (Fig. 8-5b), where a ventral cor-

bicula is usually evident, scopal hairs usually also present on trochanter, tibia, and basitarsus and sometimes on metasomal sterna 12

5(4). Facial fovea rather small but well defined (Fig. 59-1); two subantennal sutures well separated on clypeal margin below each antenna (Fig. 33-2c) [apex of marginal cell truncate or sometimes obliquely cut off (Figs. 50-1f, 53-1, 53-2, 54-1, 56-1, 58-1, 58-2, 59-2) and thus pointed, but apex well separated from wing margin] 6

—. Facial fovea absent or vaguely defined; one subantennal suture below each antenna (Fig. 33-2d) or if two, then the two nearly meeting on clypeal margin 7

6(5). Facial fovea deep, with conspicuous hairs (Fig. 50-1a, b) (Peru) Alocandreninae (Andrenidae) (Sec. 50)

—. Facial fovea shallow, hairless, shining

Panurginae (Andrenidae) (Sec. 52)

7(5). Two subantennal sutures below each antenna, the two nearly meeting at clypeal margin (Chile)

Andreninae (Andrenidae) (Sec. 51)

—. One subantennal suture below each antenna (Fig. 332d) 8

8(7). Body largely yellow; labrum with basolateral angles strongly developed, thus broadest at extreme base where articulated to clypeus (as in Fig. 33-2a); subantennal suture short, directed toward outer margin of antennal socket (pygidial and prepygidial fimbriae absent)

(Palearctic deserts)

Pararhophitini (Megachilidae) (Sec. 77)

—. Body usually exhibiting little or no yellow; labrum with basolateral angles little developed, thus not broadest at extreme base and articulation with clypeus shorter (as in Fig. 33-2b); subantennal suture usually directed toward middle or inner margins of antennal socket 9

9(8). Episternal groove extending below scrobal groove (as in Fig. 20-5b) although frequently shallow (antennae arising below middle of face)

Rophitinae (Halictidae) (Sec. 62)

—. Episternal groove not extending below scrobal groove

10(9). Glossa short, apex broadly rounded (inner hind tibial spur pectinate) (Australia) Stenotritidae (Sec. 36)

—. Glossa pointed, often with flabellum 11

11(10). L-T bees, first two segments of labial palpus elongate, flattened (Figs. 10-4a, 19-1b); episternal groove commonly present down to or curving into and joining scrobal groove (Fig. 20-5c) Apidae (Sec. 85)

—. S-T bees, first two segments of labial palpus similar in form to subsequent segments (Figs. 10-4c, 19-5b); epis-

ternal groove almost completely absent

Melittidae (Sec. 68)

12(4). Facial fovea well developed, covered with short hairs (two subantennal sutures below each antenna, often difficult to see) (Fig. 33-2c)

Andreninae (Andrenidae) (Sec. 51)

—. Facial fovea absent or not well defined, not bearing distinctive short hairs, but (/"defined, then bare 13

13(12). Stigma absent (Fig. 60-2a); two subantennal sutures below each antenna (as in Fig. 51-1a) (Western Hemisphere) Oxaeinae (Andrenidae) (Sec. 60)

—. Stigma present, although sometimes no wider than pres-tigma as measured to wing margin; ordinarily only one subantennal suture below each antenna (Fig. 33-2d) 14

14(13). Stigma almost always shorter than prestigma, vein r arising almost at its apex, margin of stigma in marginal cell concave or straight and not much longer than width of stigma (Fig. 43-1); large, robust, euceriform, hairy bees (Western Hemisphere)

Diphaglossinae (Colletidae) (Sec. 42)

—. Stigma longer than prestigma, vein r arising near its middle or at least well before its apex, margin of stigma in marginal cell straight or convex, much longer than width of stigma; andreniform bees, much more slender than those of above alternative 15

15(14). Episternal groove extending little below scrobal groove Nomiinae (Halictidae) (Sec. 63)

—. Episternal groove extending far below scrobal groove

(Fig. 20-5b), commonly onto venter of thorax 16

16(15). Basal vein only feebly arcuate (Fig. 39-5); glossa bilobed (Fig. 19-2a, b) Colletinae (Colletidae) (Sec. 39) —. Basal vein strongly curved (Fig. 65-5); glossa acutely pointed (Figs. 19-2c, d, 28-1a-c) 17

17(16). T5 with prepygidial fimbria divided by medial longitudinal zone or triangle of short, dense hairs (Fig. 65-1j) and minute, dense punctations (the hairs sometimes absent) Halictinae (Halictidae) (Sec. 65)

—. T5 with prepygidial fimbria weak but continuous (Eastern Hemisphere) Nomioidinae (Halictidae) (Sec. 64)

18(1). Episternal groove extending far below scrobal groove (Fig. 20-5b) toward ventral surface of thorax (S6 exposed, not bifurcate) 19

—. Episternal groove absent or curving into scrobal groove (Fig. 20-5a, c), extending below scrobal groove only in Caenoprosopidini (in which S6 is retracted, only its bifurcate apex exposed) 21

19(18). Glossa pointed (Fig. 19-2c, d); basal vein strongly curved (Fig. 65-5); submarginal cells usually three

Cleptoparasites in Halictinae, both tribes

(Halictidae) (Sec. 65) —. Glossa bilobed or broadly truncate (Fig. 19-2a, b); basal vein gently arcuate (Fig. 39-5); submarginal cells two, second usually much smaller than first (Figs. 47-2, 48-2,

20(19). Supraclypeal area elevated abruptly above level of antennal sockets (Fig. 47-3a); pygidial plate usually absent, but if present, then broad, its margins converging posteriorly; anterior surface of T1 usually lacking longitudinal median groove Hylaeinae (Colletidae) (Sec. 47) —. Supraclypeal area sloping up from level of antennal sockets; pygidial plate present, the apical part slender, parallel-sided or spatulate; anterior surface of T1 with longitudinal median groove

Euryglossinae (Colletidae) (Sec. 48)

21(18). S6 retracted under S5 except for apex, metasomal venter thus appearing to be five-segmented; apex of S6 bilobed, bifurcate, or produced to median spine, frequently bearing rows or clumps of stiff setae (Fig. 91-2)

—. S6 more fully exposed, the metasomal venter thus recognizably six-segmented; apex of S6 not modified as above 22

22(21). Labrum with basolateral angles strongly developed, labrum thus broad at extreme base, where articulated to clypeus (Fig. 33-2a); labral shape more or less rectangular and usually longer than broad (forewing with two submarginal cells)

Cleptoparasites in Megachilinae, all tribes

(Megachilidae) (Sec. 79) —. Labrum with basolateral angles weakly developed, labrum thus not broadest at extreme base, articulation with clypeus not extending full width oflabrum (Fig. 33-2b); labral shape often less rectangular, often rounded apically, usually broader than long 23

23(22). Epistomal suture between lateral extremity and subantennal suture arcuate, upper part of clypeus thus almost parallel-sided (Fig. 90-2); submarginal cells two

(Eastern Hemisphere)

Social parasites within Allodapini (Apidae) (Sec. 90)

—. Epistomal suture not arcuate upward in such a way that upper part of clypeus is almost parallel-sided; submarginal cells usually three

Cleptoparasites and social parasites within Apinae

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