A very large genus with many species in the United States. Florida has an estimated 35 species, none of which are endemic. Most of the species are associated with spring-flowering trees and shrubs, many in the Rosaceae and Salicaceae. Although most are broadly polylectic, a few species are oligolectic (A. violae, A. hilaris). All species nest in the soil, often in communal groups. Dirt roads and road banks as well as bare areas in lawns are favorite nesting sites. There are many subgenera. Only three species, all in the Callandrena, fly in the fall and are associated primarily with fall-flowering composites.
Any collection made on spring-flowering Rosaceous shrubs and willows should yield several species of this genus.Since the publication of Mitchell’s key in 1960, a number of revisions have been made to the genus that have resulted in the description of new species, corrections of misidentifications and misinterpretations, synonymization of species, and rearrangement of subgeneric placement of species. Users may want to consult the following publications that are listed next to the specific subgenera. To simplify identifying Andrena in Florida, modified keys to the subgenera are presented. Using these, species keys for each subgenus, if more than one species is known from Florida, are presented. Additional species not listed here should be keyed out using the full subgeneric key from the listed revision.
The following subgenera are known from Florida: Andrena (1 sp.), Archiandrena (2 sp.), Callandrena (5 sp.), Euandrena (1 sp.), Holandrena (1 sp.), Iomellissa (1 sp.), Larandrena (1 sp.), Leucandrena (1 sp.), Melandrena (7 sp.), Micrandrena (3 sp.), Parandrena (2), Scrapteropsis (6 sp.), Taeniandrena (1 sp.), Trachandrena (2 sp.), and Tylandrena (1 sp.). For subgenera with more than 1 species, keys to the species (both males and females) are provided. For subgenera with only 1 species known from Florida, only the key to subgenus is used.
Of these species, two species are not recorded from Florida but are found in Thomas County, Georgia, approximately 10 miles from the state line and may occur in nearby counties near Tallahassee, FL. Several species are from a single collection in Sumter County, FL, listed on the label as June 25, a very late date for many species to be flying, particularly in Florida. These collections, especially if other counties are not listed, should be viewed with some caution as definitive records. Where possible, I have checked all of the identifications of those species in the FSCA to verify their determination.
None of the species of the genus Andrena are endemic to Florida. With one doubtful exception, none occur south of Lake Okeechobee or in the Southeast coast of Florida. Many may be restricted to the panhandle, northern counties of the peninsula, or the central sand ridge.
1. Middle and hind tibial spurs unusually thick, their apices abruptly hooked (Terga without apical pale bands, facial fovea narrow)...Euandrena
Middle and hind tibial spurs long, slender, not bent nor markedly twisted at apical third..2
2. Inner hind tibial spur rather abruptly bent and slightly twisted at about one-third of its length from apex (T2-T4 with conspicuous, usually medially interrupted white fasciae).. Leucandrena
Inner hind tibial spur long, slender, not bent nor markedly twisted at apical third...3
3. Galeal blade as long as clypeus or slightly longer; maxillary and/or labial palpi greatly elongate (T2-T4 with pale apical fasciae, often weak)...4
Galeal blade not as long as clypeus; maxillary and labial palpi not greatly elongate...5
4. Labial palpus greatly elongate, segments 1 plus 2 three to five times as long as segments 3 plus 4 and flattened; maxillary palpus of normal length, half as long as galeal blade; basal area of labrum not much raised above general level of surface...Callandrena
Labial palpus elongate, but first two segments not unusually long nor much flattened; maxillary palpus elongate, more than half as long as galeal blade; basal area of labrum distinctly raised above general level of surface...Iomellissa
5. Pronotum without dorsolateral angle, smoothly rounded posteriorly from one posterior pronotal lobe to the other; or, if weak angle present, then without trace of lateral ridge or elevation....6
Pronotum with dorsolateral angle on posterior margin just above and in front of pronotal lobe, usually with a ridge or elevation extending down side of pronotum from dorsolateral angle, often with depressed or flattened area posterior to this ridge; angle and ridge occasionally quite weak and rarely only that part of ridge immediately above front coxa present....8
6. Propodeal triangle coarsely sculptured, often bounded posteriorly by a strong transverse carina, or if finely sculptured, then with longitudinal rugae at least basally and with transverse carina at apex...7
Propodeal triangle usually finely sculptured, usually tessellate, never with strong transverse posterior carina, or if coarsely sculptured, then without longitudinal basal rugae and/or without transverse apical carina..13
7. T2-T4 with depressed marginal zones less than half length of exposed part of each tergum medially..Scrapteropsis
T2-T4 with depressed marginal zones half or more length of exposed part of each tergum medially...Trachandrena
8. Pronotum laterally with deeply impressed groove cutting diagonally up and forward from pronotal spiracle to near midline anteriorly, this groove crossing and strongly depressing ridge extending down from dorsolateral angle; T2-T4 without apical pale fasciae or these weak and broadly interrupted; genal area broader than eye in side view; ocellooccipital distance about one and one-half to two and one-half ocellar diameters...Tylandrena
Pronotum without lateral groove, or groove not deeply impressed and not depressing dorsoventral ridge, or if diagonal groove present and depressing ridge, then terga with distinct pale apical fasciae; genal area often narrow; ocellooccipital distance often one ocellar diameter or less...9
9. Submarginal cells two...Parandrena
Submarginal cells three...10
10. Tibial scopal hairs highly plumose throughout....Archiandrena
Tibial scopal hairs simple or largely so, occasionally weakly plumose throughout...11
11. Median third of clypeus impunctate, shiny; tibial scopal hairs weakly plumose throughout; scutellum shiny, unshagreened at least medially..Larandrena
Median third of clypeus punctate or dulled by dense shagreening or tessellation or both, sometimes with impunctate and shiny area occupying much less than one-third of clypeus; tibial scopal hairs usually simple, at least medially; scutellum often opaque, dulled by fine tessellation or shagreening.....12
12. Metasomal terga usually weak, pale apical fasciae, weakly if at all punctate; pronotal dorsoventral ridge roughened below oblique groove; propodeal corbicula complete anteriorly..Andrena
Metasomal T2-T4 with distinct, pale apical fasciae often interrupted medially; the terga distinctly punctate; pronotal dorsoventral ridge usually sharp, subcarinate, or if rounded below, then propodeal corbicula incomplete anteriorly...Holandrena
13. Maxillary palpus short, usually not exceeding galea or occasionally exceeding galea by length of terminal segment; stigma narrow, tibial scopal hairs almost always plumose throughout...Callandrena
Maxillary palpus exceeding galea by at least two segments; stigma often broader than width of prestigma, as measured to wing length; tibial scopal hairs usually simple, at least medially..14
14. Length usually 9 mm or less; stigma large, first submarginal crossvein usually meeting marginal cell within two or three vein widths of stigma; propodeal corbicula usually incomplete anteriorly, often with internal hairs...Micrandrena
Length usually more than 9mm; stigma narrow or only moderately broad, first submarginal crossvein usually meeting marginal several vein widths from stigma; but if length less than 9mm or less and stigma broad, then propodeal corbicula complete anteriorly, without internal hairs...15
15. T2-T4 with pale apical fasciae of hair...Taeniandrena
T2-T4 without pale apical fasciae of hair (in a few species with incomplete fasciae)...Melandrena
1. Submarginal cells two..Parandrena
Submarginal cells three...2
2. Mouthparts elongate, galeal blade as long as clypeus or slightly longer; maxillary palpus and/or labial palpus elongate; T2-T4 with pale, often weak, apical fasciae...3
Mouthparts short, galeal blade usually not as long as clypeus; neither maxillary nor labial palpus greatly elongate, but if galeal blade as long as clypeus, then metasomal terga lacking pale apical fasciae...4
3. Labial palpus greatly elongate, segments 1 and 2 three to five times as long as segments 3 and 4 taken together, first two segments greatly flattened; maxillary palpus normal in length, half as long as galeal blade...Callandrena
Labial palpus elongate but normal, first two segments neither unusually long or flattened; maxillary palpus usually about as long as galeal blade or much longer...Iomellissa
4. Middle and hind tibial spurs unusually thick, their apices rather abruptly hooked; terga without pale apical fasciae; clypeus black..Euandrena
Middle and hind tibial spurs neither unusually thickened nor strongly hooked at apices; terga often with pale apical fasciae ...5
5. Inner hind tibial spur rather abruptly bent and slightly twisted at about one-third length from apex; T3-T4 with pale apical fasciae and distinct punctures...Leucandrena
Inner hind tibial spur long, slender, neither bent abruptly nor twisted in apical third; T3-T4 with or without pale apical fasciae; often impunctate...6
6. Pronotum with distinct dorsolateral angle along posterior margin, and with more or less distinct dorsoventral ridge extending down from angle to anterior coxa, area between ridge and pronotal lobe often shiny and impunctate, occasionally deep and narrow or rugulose...7
Pronotum without dorsolateral angle along posterior margin, without dorsoventral ridge...13
7. Maxillary palpus short, not exceeding galea (when extended distad) by more than length of apical segment of palpus; stigma usually narrower than prestigma, as measured to anterior margin of wing; clypeus yellow....Callandrena
Maxillary palpus usually exceeding galea by at least last two lengths of last palpal segments; stigma variable, often broader than or equal to prestigma, as measured by wing margin; but, if palpus short and stigma narrow, then clypeus black...8
8. Clypeus partially or wholly yellow or cream-colored...9
Clypeus entirely black...11
9. Pygidial plate well developed, narrow, V-shaped; first flagellar segment usually about two-thirds as long as second...Archiandrena
Pygidial plate absent or vestigial (narrow and linear when present); first flagellar segment usually as long or almost as long as second...10
10. Stigma large, broader than prestigma as measured to anterior wing margin; first submarginal crossvein meeting marginal cell within three to four vein widths of stigma or less; pronotum with dorsoventral ridge crossed by distinctly impressed oblique groove...Larandrena
Stigma narrower, or, if as above, then first submarginal crossvein meeting marginal cell at more than four vein widths from stigma; pronotum with dorsoventral ridge relatively sharp, not depressed by oblique groove...Holandrena
11. Pronotum with dorsoventral ridge extending down from dorsolateral angle interrupted by distinct, oblique, deeply impressed groove, or, if groove present, then a mere line; T2-T4 usually without pale apical fasciae; clypeus short, not produced much beyond level of lower ends of compound eyes...Tylandrena
Pronotum with dorsoventral ridge extending down from dorsolateral angle not interrupted by distinctly impressed groove, or, if groove present, then a mere line; T2-T4 often with pale apical fasciae; clypeus often produced by as much as one-fourth or more of median length beyond level of lower ends of compound eyes...Andrena
12. Maxillary palpus short, rarely exceeding galea when extended distad or exceeding galea by less than length of last two palpal segments..Callandrena
Maxillary palpus long, exceeding galea when extended distad by at least length of last two palpal segments...13
13. Stigma large, first submarginal crossvein ending one to three vein widths from stigma; body 9 mm or less in length...Micrandrena
Stigma narrower, first submarginal crossvein usually ending more than three vein widths from stigma; body usually more than 9mm in length...14
14. Pleura and propodeal triangle coarsely or moderately coarsely sculptured, or, if finely sculptured, then genal area narrow, about as wide as eye in side view...15
Pleura and propodeal triangle usually finely sculptured, often merely granular or tessellate, or, if moderately coarsely sculptured, then genal area much broader than eye in side view...18
15. Propodeal triangle coarsely areolate or irregularly rugose, with transverse posterior carina separating dorsal from posterior surface....16
Propodeal triangle coarsely punctate or finely areolate, without transverse carina separating dorsal from posterior surface..17
16. Marginal zone of T2 one-third or more of median tergal length; third flagellar segment usually two-thirds as wide as long or longer; antennae in repose usually reaching beyond scutellum; First recurrent vein meeting second submarginal cell near middle of cell, rarely beyond..Trachandrena
Marginal zone of T2 less than one-third of median tergal length; third flagellar segment distinctly more than two-thirds as wide as long or longer; antennae in repose usually not reaching middle of scutellum; first recurrent vein meeting second submarginal cell two-thirds or more of length of cell from base...Scrapteropsis
17. Clypeus flattened mediobasally; metasomal terga distinctly punctate; surface and bottoms of punctures dulled by fine tessellation; T2-T5 with pale apical fasciae, but these often interrupted medially..Taeniandrena
Clypeus usually not flattened mediobasally; metasomal terga punctate but shiny or moderately so, at most dulled by fine reticulate shagreening; T2-T5 without pale apical fasciae (or weak and interrupted)...Melandrena
18. Genal area narrow, at most slightly broader than eye in lateral view; metasomal sterna usually with pale subapical fimbriae....Euandrena
Genal area conspicuously broader than eye in lateral view; metasomal sterna without pale subapical fimbriae...19
19. T2-T4 and often T5 with more or less distinct pale apical fasciae; ocelloccipital distance about one ocellar diameter, often less and rarely slightly more...Leucandrena
T2-T5 without pale apical fasciae, or, if present, on some terga, then weak, and ocelloccipital distance at least one and one-half ocellar diameters, often more...Melandrena
