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© Copyright source/photographer
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Andrena caerulea, female, dorsal, Tenalquot |
© Copyright source/photographer
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Andrena caerulea, female, head, Tenalquot |
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© Copyright source/photographer
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Andrena caerulea, female, lateral, Tenalquot |
© Copyright John Ascher, 2006-2014
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Andrena caerulea, Cerulean Andrena |
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© Copyright Laurence Packer 2014
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Andrena caerulea FEM CFP |
© Copyright Laurence Packer 2014
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Andrena caerulea MALE mm x ZS PMax |
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© Copyright source/photographer
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Andrena caerulea, f, back, Santa Barbara, CA |
© Copyright source/photographer
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Andrena caerulea, f, face, Santa Barbara, CA |
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© Copyright source/photographer
· 5
Andrena caerulea, f, side, Santa Barbara, CA |
© Copyright John Ascher, 2006-2014
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Andrena caerulea, Cerulean Andrena |
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Smithsonian Institution, Entomology Department · 1
Andrena caerulea, face |
Smithsonian Institution, Entomology Department · 1
Andrena caerulea, side |
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Smithsonian Institution, Entomology Department · 1
Andrena caerulea, top |
Smithsonian Institution, Entomology Department · 1
Andrena caerulea, wing |
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Overview |
Reprinted with permission of the American Entomological Society from:
LaBerge, W. E., Ribble, D. W. 1975. A revision of the bees of the genus Andrena of the Western Hemisphere. Part VII. Subgenus Euandrena. Transactions of the American Entomological Society 101: 371-446.
Please report text errors to: leah at discoverlife dot org.
Andrena caerulea is a small Rocky Mountain and West Coast species. The species name is often spelled coerulea due to differing interpretation of the italicized diphthong. It is unfortunate that the name complexa has been most commonly used for this species and that several biological papers use this name.
Both sexes of A. caerulea can be separated from related bees by the metallic coloration, the short clypeus which is only obscurely punctate, and the highly plumose hairs of the tibial scopae, the propodeal corbicula and the dorsal femoral flocculus. The descriptions given below are based on specimens from the Berkeley, California area.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 7.5-10.5 mm; width, 2-3 mm; wing length, M = 3.18 ± 0.1S2 mm; FL/FW, M = 1.01 ± 0.006; FOVL/FOVW, M = 3.72 ± 0.083.
INTEGUMENTAL COLOR. — Black with metallic blue-green luster except as follows: mandible with apical half rufescent; antenna brown below; clypeus with violaceous reflections; wing membrane moderately infumate, amber, veins dark brown; tegulae testaceous at summits; legs brown, tibial spur amber; sterna black with bluish reflections to brown.
STRUCTURE. — Antennal scape nearly as long as first four flagellar segments; flagellar segment 1 slightly longer than segments 2 plus 3; segment 2 equal in length to 3, broader than long and shorter than 4; segments 4-9 quadrate. Eyes each about four times as long as broad, inner margins slightly converging towards mandibles. Mandible moderately long, at rest surpassing far corner of labrum, with inner subapical tooth. Galea pointed, moderately broad, surface dulled by fine reticular shagreening. Maxillary palpus surpassing galea by more than last two segments, segmental ratio about as 0.7:1.0:0.9:0.9:0.6:0.8. Labial palpus with first segment flattened, long, curved, segmental ratio about as 1.0:0.5:0.5:0.6. Labral process subtrapezoidal, entire or only slightly emarginate; labrum below process flattened, shiny. Clypeus moderate in length, rounded side to side; punctures small, indistinct due to fine, dense, reticular shagreening, apically punctures larger. Supraclypeal area dulled by fine rugulae and shagreening. Face above antennal fossae with distinct longitudinal rugulae and fine shagreening. Facial fovea small, slightly wider dorsally; separated from lateral ocellus by one and one-half to two ocellar diameters, extending down to about level of lower margins antennal fossae. Vertex above lateral ocellus less than one ocellar diameter (usually 6 or 7:8). Genal area in profile only slightly wider than eye; surface dulled by minute obscure punctures and fine reticular shagreening.
Pronotum dulled by fine shagreening and minute punctures. Mesoscutum moderately punctate, punctures separated mostly by two puncture widths, surface dulled by reticular shagreening. Scutellum similar to mesoscutum. Propodeum with dorsal area finely tessellate with few short basal irregular rugulae; dorsolateral and posterior surfaces with fine distinct punctures obscured by even tessellation. Mesepisternum sculptured as posterior surface propodeum. Wings with pterostigma medium-sized, broader than from inner margin prestigma to wing margin; vein 1st m-cu meets second submarginal cell near center of cell; second submarginal cell subquadrate, slightly narrowed anteriorly, medium-sized; hind wing with vannal lobe moderately narrow, at excision about one and one-half times wide as apical end of cell Cu or narrower. Tarsal claws with large, inner, subapical tooth; hind tibia moderately broadened apically.
Metasomal terga 1-4 with distinct apicolateral elevations, with minute punctures and fine reticular shagreening, granduli hidden with abdomen in normal position. tergum 5 with larger punctures and shagreening. Pygidial plate V-shaped with rounded apex, shagreened medially, margins gradually upturned (when not worn), internal ridge raised but rounded. Sterna 2-5 with small punctures and fine reticular shagreening (punctures absent in narrow apical marginal area and at extreme bases).
VESTITURE. — Generally white with the following exceptions: face with mostly dark hairs, genal areas with few dark hairs dorsally; legs mostly amber to brown hairs (scopal hairs vary from almost while to dark brown); metasomal terga 5 and 6 dark brown. Propodeal corbicula incomplete anteriorly with many, long, highly plumose, internal hairs; tibial scopal hairs abundant, shortened towards apex, highly plumose but less so than those in propodeum, with long wavy branches; hind femur (especially above) and trochanter with hairs highly plumose like those of corbicula. Metasomal terga 2-4 with hairs of moderate length, sparse, apical fasciae absent or extremely weak. Sterna 2-5 with weak subapical fimbriae.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length 6-10 mm; width, 1.5-2.5 mm; wine length, M = 2.86 ± 0.187 mm; FL/FW, M = 1.03 ± 0.008; FS1/FS2, M = 1.82 ± 0.050.
INTEGUMENTAL COLOR. — As in female but luster more bluish, some blue reflections on larger leg segments and metasomal sterna.
STRUCTURE. — Antenna moderately long, reaching metanotum in repose; scape length about equal to first two and one-third flagellar segments; flagellar segment 1 nearly as long as segments 2 plus 3, segment 2 shorter than 3 and about as broad as long, segments 3-11 longer than broad. Eyes, mandible and galea as in female. Maxillary palpus as in female but ratio about as 0.8:1.0:0.8:0.7:0.7:1.0. Labial palpus as in female but ratio about as 1.0:0.6:0.6:0.7. Labral process small, squarish, expanded at base, usually emarginate apically, elevated; labrum apical to process as in female. Clypeus, supraclypeal are;>, and face above antennal fossae as in female. Facial fovea weakly developed. Vertex above lateral ocellus equal to one ocellar diameter, slightly more or less. Genal area as in female.
Thorax as in female except propodeal sculpturing, outside of enclosure, coarser; hind tibia unmodified.
Metasoma as in female except tergum 5 sculptured as in terga 2-4; pygidial plate absent.
Terminalia as in figures 35-39; note the following: gonocoxite slightly narrowed apically; sternum 7 with apical emargination U-shaped; sternum 8 with apex broadly rounded.
VESTITURE. — Generally as in female but dark hairs restricted to face, genal area and lateral surfaces of propodeum; pollen-collecting hairs absent; terga with apical fasciae absent or extremely weakly developed; sternal fimbriae present but weak.
VARIATION. — Several kinds of variation occur in A. caerulea and these are poorly correlated with one another. Linsley and MacSwain (1957) state, "These instances have been in montane areas where the average size of he bees is much less than in the lowlands and coastal areas." Later (Linsley and MacSwain, 1959) they state, "At higher elevations in the more northern part of California, populations are made up of individuals with a slightly smaller average size. We would modify these statements somewhat to state that Andrena caerulea specimens from localities outside of the San Francisco Bay area average smaller in size. The largest specimens occur in the Bay area, along with others of average size.
Typically, the females of caerulea are bright blue-green in color but a few specimens (San Francisco, Oakland, McClures Beach) from the Bay area are blue-black. Typical specimens have been collected in the same or nearby localities as the blue-black specimens. Individuals which are more blue than green also occur in the Sierra Nevada Mountains and as far north as Oregon and Idaho, so we are dealing with individual variation.
Males, which are generally bluer to start with, do not show this type of variation in color. However, (he males, as well as the females, do tend to be darker in color in the Sierras and northern California northward, with a few specimens lacking the blue or green reflections almost completely. However, greenish or gold females and gold males can occur in these areas.
Most females have the vestiture mostly pale, but some specimens from the Bay area have the pale hairs restricted to the thoracic dorsum and terga 1 and 2. There are specimens representing all states between these two extremes and a considerable amount of this variation can occur within one locality. Specimens with considerable amounts of dark hairs are found in other parts of the range (for example, Santa Cruz Island and Moscow, Idaho) but the darkest females are from the Bay area. Males are always paler and generally have mostly white hairs.
The clypeus of A. caerulea varies in punctation. Normally the punctures are obscured by the dense shagreening, but sometimes they are more distinct, closely approaching the condition found in A. nigrocaerulea. More punctate specimens of caerulea come from throughout the range of the species and occur along with normal individuals. At some localities in the Sierras (for example, Wrights Lake) the punctate or partially punctate specimens are common, making up the bulk of the specimens.
Some female specimens from McClures Beach, Marin County, California, have especially long hairs on the terga, giving them a very shaggy appearance. Other specimens from the same locality are normal in hair length.
Occasional specimens from the Sierras and the mountains of northern California have the hairs shortened on the thoracic dorsum. The body hairs are also dead white and highly plumose. These bees are quite distinctive in appearance. This type of variation in hair-length is usually associated with desert Andrena.
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Updated: 2024-04-23 19:37:39 gmt
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