Key to the Families Based on Adults

The key to families below is intended to work for the great majority of bees, but exceptions to some of the characters of some couplets exist, usually in rare or geographically limited taxa. These problems are addressed in the notes in Section 34, each note keyed to the pertinent couplet number.

Some general attributes of the families are discussed in Section 21, and the bases for the recognition of families are discussed in Sections 18 to 21, as well as in the main systematic text, Sections 36 to 121. Many of the diagnostic familial characters are in the proboscis, which must be extended for study. Moreover, most of the characters that can be seen without extending the proboscis or dissecting the male genitalia and hidden sterna are variable within families and so not valuable in identifying families. Paradoxically, then, it is often easier to identify the subfamily or tribe, or even the genus, of a bee than to identify its family. The regional keys to genera found in the works listed in Table 32-1, above, often facilitate identification. Section 35, which deals with the practical problems of identification of female bees, should also be helpful.

Key to the Families of Bees, Based on Adults

1. Labial palpus with first two segments elongate (Fig. 33-1a), flattened, the last two segments small, usually diverging laterally from axis of first two, not flattened, rarely absent; galeal comb absent or rarely weakly indicated; stipital comb and concavity commonly present (Figs. 19-1a, 33-1b); galeal blade elongate, commonly as long as or longer than stipes (Fig. 33-1b); volsella frequently absent or difficult to recognize, rarely with distinct digitus and cuspis [L-T

—. Labial palpus with the four segments similar to one another (Fig. 33-1c), or first or rarely first two elongate but not much flattened; galeal comb commonly present; stipital comb and concavity absent (Fig. 33-1d); galeal blade usually shorter than stipes (Fig. 33-1d); volsella commonly well developed, usually with recognizable digitus and cuspis [S-T (short-tongued) bees] 3

Figure 33-1. Proboscides. a, b, Labium and maxilla of Anthidium atripes Cresson (Megachilidae); c, d, Labium and maxilla of An-drena mimetica Cockerell (Andrenidae). From Michener, 1944.

2(1). Labrum with basolateral angles enlarged, base forming broad articulation with clypeus, labrum thus widest at base (Fig. 33-2a); labrum at least 0.8 times as long as broad and usually as long as broad or longer; forewing with two submarginal cells, usually about equal in length (except with three in Fideliini); scopa, when present, restricted to metasomal sterna Megachilidae (Sec. 75)

—. Labrum with basolateral angles little developed, articu

Figure 33-2. Labra and faces. a, Labrum of Heriades apriculus Griswold, female (Megachilidae); b, Labrum of Anthophora ed-wardsiiCresson, male (Apidae); c, Face of Andrena mimetica Cockerell, female (Andrenidae); d, Face of Halictus farinosus

Smith, female (Halictidae). (The heavy lines across the tops of a and b represent diagrammatically the clypeal articulations. b, c, from Michener 1944.

lation with clypeus thus narrower than full width of labrum (Fig. 33-2b); labrum usually broader than long, but in some parasitic forms (where scopa is absent) labrum elongate; forewing with two or three submarginal cells, rarely only one; scopa, when present, on hind leg, particularly the tibia, and usually absent on metasomal sterna Apidae (Sec. 85)

3(1). Glossa pointed at apex, sometimes with flabellum 4

—. Glossa bluntly rounded, truncate, or bilobed at apex (except pointed in males of three hylaeine genera from

Australia-New Guinea area); flabellum absent 7

4(3). Lacinia represented by scalelike lobe with hairs near base of galea (Fig. 33-1b, d); mentum and lorum forming proboscidial lobe (Figs. 33-3b-f, 33-4b), both at least partly sclerotized; lorum not flat 5

—. Lacinia inconspicuous or displaced, not a scalelike lobe at base of galea (Fig. 21-2a, b); mentum and lorum not forming proboscidial lobe (Figs. 33-3h, i, 34-4a), men-tum sometimes membranous; lorum membranous or nearly flat sclerotized membrane (apron) between cardines (Figs. 33-3h, 33-4a) 6

5(4). Lorum more or less platelike but produced in middle for attachment to base of mentum; facial fovea present in females (Fig. 33-2c) and some males, fovea sometimes a groove rather than broad as in figure; subantennal area almost always defined by two subantennal sutures below each antennal socket (Fig. 33-2c)

Andreninae and Panurginae (Andrenidae) (Sec. 49)

—. Lorum slender, V-shaped or Y-shaped, as in L-T bees (Fig. 33-1a); facial fovea absent; a single subantennal suture below each antennal socket (as in Fig. 33-2d)

Melittidae (Sec. 68)

6(4). Lacinia a small, hairless sclerite hidden between expanded stipites; subantennal area defined by two suban-tennal sutures below each antennal socket (as in Fig. 33-2c); stigma nearly absent; first flagellar segment as long as scape or longer Oxaeinae (Andrenidae) (Sec. 60)

—. Lacinia represented by small, hairy lobe on anterior surface of labiomaxillary tube above rest of maxilla (Fig. 21-2a); a single subantennal suture below each antennal socket (Fig. 33-2d); stigma well developed; first flagellar segment much shorter than scape Halictidae (Sec. 61)

7(3). Apex of glossa bluntly rounded, without preapical fringe or apical glossal lobes; episternal groove absent below scrobal groove; scopa present on hind tibia, but absent on femur Stenotritidae (Sec. 36)

—. Apex of glossa truncate to bilobed (except pointed in males of three genera in Australia-New Guinea region); episternal groove usually present below scrobal groove; scopa, when present, well developed on hind femur as well as tibia Colletidae (Sec. 37)

Figure 33-3. Diagrams of basal sclerites of labium, posterior views of lorum, mentum, and basal part of prementum, extended and arranged in a single plane, and lateral views of same sclerites in more natural position. a, Anthophora occidentalis Cresson (Api-dae); b, Melitta leporina (Panzer) (Melittidae); c, Melitturga clavi-cornis (Latreille) (Andrenidae); d, Panurgus calcaratus (Scopoli) (Andrenidae); e, Pseudopanurgus aethiops (Cresson) (Andrenidae); f, Megandrena enceliae (Cockerell) (Andrenidae); g, An-drena erythrogaster(Ashmead) (Andrenidae); h, Protoxaea gloriosa (Fox) (Andrenidae); i, Lasioglossum calceatum (Scopoli)

Figure 33-3. Diagrams of basal sclerites of labium, posterior views of lorum, mentum, and basal part of prementum, extended and arranged in a single plane, and lateral views of same sclerites in more natural position. a, Anthophora occidentalis Cresson (Api-dae); b, Melitta leporina (Panzer) (Melittidae); c, Melitturga clavi-cornis (Latreille) (Andrenidae); d, Panurgus calcaratus (Scopoli) (Andrenidae); e, Pseudopanurgus aethiops (Cresson) (Andrenidae); f, Megandrena enceliae (Cockerell) (Andrenidae); g, An-drena erythrogaster(Ashmead) (Andrenidae); h, Protoxaea gloriosa (Fox) (Andrenidae); i, Lasioglossum calceatum (Scopoli)

(Halictidae). Abbreviations used here and in Figure 33-4 are: LA, loral apron; L, lorum; M, mentum; PM, prementum; F, basal fragmen-tum of prementum; A, basal apodeme of prementum; S, area of lorum lying against shaft of cardo, or in L-T and melittid bees, against apex of cardo. (Only the profiles of unsclerotized mentums or portions of mentums are shown, as dotted lines. Dots represent membrane. Dotted areas above lorums represent the membranous posterior surface of the labiomaxillary tube, extending toward its attachment to the head.) From Michener, 1985a.

Figure 33-4. Diagrams of basal sclerites of labium, as explained for Figure 33-3. a, Systropha curvicornis (Scopoli) (Halictidae); b, Lon-chopria herbsti Vachal (Colletidae); c, Colletes inaequalis Say (Col-letidae); d, Caupolicana hirsuta Spinola (Colletidae); e, Euryglossa subsericea Cockerell (Colletidae); f, Amphylaeus morosus (Smith) (Colletidae); g, Ctenocolletes albomarginatus Michener (Stenotriti-dae). (For abbreviations, see legend, Fig. 33-3.) From Michener, 1985a.

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