Short Tongued versus Long Tongued Bees

At least since Kirby (1802), it has been the custom of specialists on bees, unlike other hymenopterists, to devote a great deal of attention to mouthparts. Continuing this practice, recent phylogenetic studies (Roig-Alsina and Michener, 1993; Alexander and Michener, 1995) have been heavily weighted by numerous characters of mouth-parts. An old atlas of proboscides of bees, that of Saun-ders (1891), shows many of the characters discussed below. From at least as early as Kirby's monograph (1802) to the present, it has been common to recognize two groups, the short-tongued (S-T) bees and the long-tongued (L-T) bees. Some older classifications gave these two groups formal status, as indicated in Section 18 for the classifications of Kirby (1802) and Latreille (1802b). Later classifications mostly divided bees into more families, a series of S-T families followed by a series of L-T families. Thus the distinction between S-T and L-T families tended to be preserved.

S-T bees as a group are paraphyletic, having given rise to the L-T bees (see Sec. 20). Indeed, as shown below, the family Melittidae is probably the paraphyletic source of the L-T bees. But since S-T and L-T bees differ in many features, distinguishing these groups remains useful and they are differentiated below.

In L-T bees the first two segments of the labial palpi are ordinarily elongate, flattened and sheathlike (Fig. 19-1b), forming, along with the maxillary galeae, a tube or channel in which the glossa can move back and forth. In S-T bees these palpal segments are unmodified (Fig. 19-2b, d) or the first one is sometimes elongate, the first two being elongate only in a few genera, such as Morawitzia and Rophites s. str. (Rophitinae), Protomeliturga (Pa-nurginae), and Andrena (Callandrena) micheneriana LaBerge (Andreninae). L-T bees also lack the galeal comb, or it is extremely reduced; commonly, however,

Figure 19-1. Proboscis of an L-T bee, Anthophora edwardsii Cresson. a, Outer view of maxilla; b, Posterior view of labium and basal parts of maxilla; c, Lateral view of labium, the distal parts of the they have a concavity and comb on the posterior distal margin of the maxillary stipes (Fig. 19-1a), although the comb is absent in most Megachilidae and is probably lost in most Nomadinae, and in some of those forms the concavity is also absent. S-T bees commonly have a comb (Fig. 19-5a) on the inner surface of the galea (not visible in outer view, Fig. 19-2a; but see Figs. 21-1, 21-2a). This comb is absent in some S-T groups, e.g., the Halictinae (Fig. 21-2b) except Corynura and its relatives. Except for Eremaphanta in the Melittidae, S-T bees lack a stipital comb and concavity. In L-T bees the glossa is nearly always elongate (Fig. 19-1b) with a deep, longitudinal groove on its posterior surface (Fig. 19-3b-d), the lips of the groove margined by small hairs and nearly meeting to enclose a channel (Fig. 19-3c), the glossal canal (Mich-ener and Brooks, 1984). On the anterior surface of the glossal canal there is almost always a longitudinal thickening, the glossal rod, lateral to which are minute, simple seriate hairs directed mesodistally. Clearly, these are synapomorphies; in nearly all other bees the glossa has at most a broad, shallow concavity running along all or part of the posterior surface and margined by hairs similar to other glossal hairs. The seriate hairs are exposed, relatively large, often branched, and directed laterodistally (Fig. 194e, f). As shown by Michener and Brooks (1984), however, in Melitturga (Panurginae) the channel is almost as well formed as in an L-T bee.

Other characters that distinguish most or all L-T bees from most or all S-T bees are indicated by Michener and Greenberg (1980), Roig-Alsina and Michener (1993), and Alexander and Michener (1995). As noted by these authors as well as by Laroca, Michener, and Hofmeister (1989), the expressions L-T and S-T are not always appropriate, for there are L-T bees with short glossae (Fig. 8-1) and S-T bees with long glossae (Fig. 19-5c). Among glossa and labial palpus omitted; d, Flabellum. From Michener, 1944.

conjunctivali thickening L

lacinia-

galea conjunctivali thickening L

lacinia-

galea

stipital comb

Figure 19-1. Proboscis of an L-T bee, Anthophora edwardsii Cresson. a, Outer view of maxilla; b, Posterior view of labium and basal parts of maxilla; c, Lateral view of labium, the distal parts of the cardo -

mentum mentum-

conjunctival lorum thickening, stipesT

maxillary prementum-palpus stipital comb glossa mentum cardo -

mentum-

conjunctival lorum thickening, stipesT

maxillary prementum-palpus glossa

conjunctival thickening prementum

■1 st segment, labial palpus paraglossa glossa and labial palpus omitted; d, Flabellum. From Michener, 1944.

conjunctival thickening prementum

■1 st segment, labial palpus paraglossa

cardo maxillary palpus cardo stipes 0

conjunctival thickening

prementum stipes glossa' paraglossa

0 labial palpus'

prementum stipes 0

conjunctival thickening maxillary palpus glossa' paraglossa stipes

0 labial palpus'

paraglossa glossa paraglossa glossa parasitic Allodapini there exist species obviously related to the nonparasitic L-T allodapines but with the basal segments of the labial palpi and the glossa relatively short (Fig. 8-1). This trend reaches its extreme in the South African parasitic genus Eucondylops (Michener, 1970). The parasitic allodapines are mostly not known to visit flowers; they must feed in the nests of their host bees, other allodapines. Thus they do not need equipment for extracting nectar from flowers and appear to have lost it. Likewise, as emphasized by Silveira (1993a), the genus Ancyla (Ancylini), which visits shallow-flowered plants such as the Apiaceae (Popov, 1949b), has no long flat seg-

Figure 19-2. Proboscides of S-T bees. a, b, Colletes fulgidus Swenk; c, d, Halictus farinosus Smith. (a and c are outer views of maxillae; b and d are posterior views of labia.) The not or weakly sclerotized basal connections of the prementum are not shown in d. From Michener, 1944.

ments of the labial palpi (Fig. 107-2), and yet it seems to be a relative of Tarsalia, an obvious L-T bee (see Silveira, 1993b). Warncke (1979c) separated Ancyla and Tarsalia only subgenerically. Finally, Cenoplectra, often given familial status because of its combination of characteristics

Figure 19-3. Diagrams of the glossa of an L-T bee, with structures labeled. a, b, Anterior and posterior surfaces; c, Cross section of same, the anterior surface above; d, Inner surface of a portion of the glossal canal and adjacent edge of the annulate surface, flattened out. From Michener and Brooks, 1984.

Figure 19-3. Diagrams of the glossa of an L-T bee, with structures labeled. a, b, Anterior and posterior surfaces; c, Cross section of same, the anterior surface above; d, Inner surface of a portion of the glossal canal and adjacent edge of the annulate surface, flattened out. From Michener and Brooks, 1984.

Figure 19-4. Diagrams of colletid and halictid glossae, with structures labeled. a, b, Anterior and posterior surfaces of the glossa of a colletid; c, Cross section of same, the anterior surface above; d, e, Anterior and posterior surfaces of the glossa of a halictid; f, Cross section of same, the anterior surface above. From Michener and Brooks, 1984.

setae setae

glossal lobe basiglossal sclerite basiglossal sensilla preannular area disannulate surface annulate surface preapical fringe glossal brush mdMâim mdMâim

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