Reprinted with permission of the American Entomological Society from:
Ribble, D. W. 1974. A revision of the bees of the genus Andrena of the Western Hemisphere. Subgenus Scaphandrena. Transactions of the American Entomological Society 100: 101-189.
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The female of this species is most easily distinguished by the large ridge behind the lateral ocelli. Female plana have this ridge weakly developed and are easily separated with other characters. The males of mackieae do not appear to belong to Scaphandrena or related subgenera. They have long mandibles, long antennae, apical abdominal fasciae absent, humeral angles and a large process on the gena at the base of the mandible. Humeral angles are common in Andrena but are not found in other members of the Scaphandrena/Micrandrena/Thysandrena complex of subgenera. The humeral angle is unusual in that it is not straight but curves posteriorly on the dorsal surface of the pronotum, the humerus is flattened in side view and rounded in anterior view. The large process on the gena is reminiscent of some saber-toothed tigers in which the lower jaw extended downward to protect the canines. The rare A. cerebrata from the eastern United States has a similar process (Mitchell, 1960). Andrew cerebrata is unassigned to a subgenus due to the lack of females but it appears not to be a Scaphandrena on the basis of other characters and therefore its process would be of independent origin (convergent evolution) from mackieae. Some male bees of the genus Perdita also have a process of the gena (Timberlake, 1964) but the process is higher, away from the mandible and may well have a different function. The descriptions below are based mainly on a female from Exchequer Dam, Mariposa Co., and a male from Davis.
FEMALE. — MEASUREMENTS AND RATIOS. — Length, 10.2 mm; width, 2.8 mm; wing length, 7.7 mm; FL/FW, 0.90; FOVL/FOVW, 3.67.
INTEGUMENTAL COLOR. — Color as in scurra but body with slight metallic luster, hind legs entirely dark.
STRUCTURE. — Flagellar segment 1 about as long as 2 plus 3; segments 4-9 longer than broad; antenna otherwise as in scurra. Eyes each about 3.4 times as long as broad, inner margins nearly parallel. Mandible as in scurra. Galea pointed, moderate in width, shiny with faint shagreening. Stipes with few long straight hairs. Labial palpus as in scurra but ratio about 1.0:0.5:0.6:0.8. Maxillary palpus surpassing galea by less than last two segments, segmental ratio about as 0.9;\.0'.0.6-.O.S-.0.6-.0.&. 'Labia\ process moderate in size, subtriangular, truncate at apex, elevated; labrum below process flattened except for median longitudinal carina. Clypeus as in scurra but shagreening coarser, surface at apex uneven with shiny areas. Supraclypeal area and face above antennal fossae as in scurra but face with rather weak rugulae. Facial fovea broad, separated from lateral ocellus by about one ocellar diameter, extending down to below level of lower margins antennal fossae. Vertex above lateral ocellus elevated rather abruptly upward into ridge, vertex about as high as one ocellar diameter. Genal area as in scurra but shagreening rather coarse.
Pronotum as in scurra but with faint humeral angle (see male description), shagreening rather coarse. Mesoscutum as in scurra except shagreening coarser, center not differentiated from rest of scutum. Scutellum sculptured as mesoscutum but shinier. Propodeum with dorsal area triangular with coarse but regular reticular shagreening; remainder of propodeum as in scurra except shagreening on dorsolateral and posterior surfaces smoother and more regular. Mesepisternum as in scurra except shagreening coarser. Wings as in scurra except pterostigma slightly larger. Tarsal claws as in scurra: hind tibia moderately widened.
Metasomal tergum 1 without apicolateral elevation, graduli distinct on terga 3 and 4, otherwise as in scurra. Pygidial plate U-shaped; internally plate rather smooth and flat; margin slightly upturned. Sterna 2-5 with close, medium punctures, surfaces otherwise as in scurra.
VESTITURE. — Generally white except dorsum of thorax with distinctly yellowish hairs; brownish hairs on facial fovea under some lightings, on "knee" joint of hind legs, on apex of abdomen; hairs abundant. Thoracic dorsum as in scurra but hairs sparser; propodeal corbicula as in scurra; tibial scopal hairs of moderate length towards apex of tibia, many hairs along anterior margin curved anteriorly, tibial hairs otherwise as in scurra. Metasomal terga 2-4 with apical white fasciae moderately well developed, band broadly interrupted on tergum 2; sternal hairs as in scurra.
MALE. — MEASUREMENTS AND RATIOS. — Length, 7.0 mm; width, 1.8 mm.; wing length, 6.4 mm; PL/FW, 0.89; FS1/FS2, 1.07.
INTEGUMENTAL COLOR. — Color as in female except clypeus yellow except apex and two small dark spots.
STRUCTURE. — Antenna long, reaching posterior part of propodeum in repose; scape length equal to first two and one-half flagellar segments; flagellar segment 1 only slightly longer than segment 2; segment 2 only slightly shorter than 3, almost twice as long as broad; segments 3-11 twice as long as broad. Eyes with inner margins converging slightly towards mandibles, otherwise as in scurra. Mandible long, curved, sharply pointed, decussate in repose; subapical tooth present. Galea as in female. Stipes bare. Labial palpus as in female but ratio about 1.0:0.5:0.5:0.6. Maxillary palpus as in female but ratio about 1.0:1.0:1.0:1.0:0.7:1.0. Labral process moderate in size, trapezoidal, deeply notched at apex, elevated; labrum apical to process as in female but carina much reduced. Clypeus slightly bowed anteriorly, shiny, shagreening weak to absent, few small scattered punctures laterally. Supraclypeal area, face above antennal fossae, vertex as in female. Genal area one and one-half times as wide as eye in profile, relatively shiny, rather fine reticular shagreening; very shiny without shagreening along eye margin; large finger-like process at base of mandible, somewhat twisted, meeting and surpassing mandible in repose.
Pronotum with large ridge extending vertically from forecoxa, ridge curving posteriorly on dorsolateral surface; pronotum excavated behind ridge, shiny; microsculpture on dorsal surface as in female. Mesoscutum as in female. Scutellum in center very shiny with weak shagreening. Propodeum and mesepisternum as in female. Wings as in female but vein 1st m-cu meets second submarginal cell before middle of cell. Tarsal claws as in scurra; hind tibia slightly swollen at apex.
Metasomal sculpturing as in female but gradulus distinct only on tergum 3; pygidial plate absent; sterna 2-5 with more scattered punctures. Sternum 6 deeply emarginate.
Terminalia as in figures 59-63; note the following: gonocoxite with dorsal lobes long, pointed, narrow at tip with narrowly rounded apex, gonocoxite at apex rather long and slender; penis valve long, slender, dorsal lamellae absent, apex long, slender, slightly expanded, narrowly rounded; sternum 7 with small apical notch; sternum 8 with apex not broader than neck.
VESTITURE. — Generally dirty white otherwise as in scurra except hairs fewer, apical fasciae reduced to a few long lateral hairs.
VARIATION. — Some males have large heads out of proportion to their size. This is common in some groups of Andrena but not in Scaphandrena and related subgenera. The females vary in size, one female (wing length, 6.6 mm) is only about half the size of an average female.
Reprinted with permission of the American Entomological Society from:
LaBerge, W. E. 1985. A revision of the bees of the genus Andrena of the Western Hemisphere. Part XI. Minor subgenera and subgeneric key. Transactions of the American Entomological Society 111: 440-567.
Andrena mackieae was adequately redescribed by Ribble (1974), and only a brief diagnosis listing characters separating mackieae from its eastern relative, A. cerebrata, is included here together with a summary of new distributional and host records.
The female of mackieae can be separated from that of cerebrata by the broad facial foveae and the simple tibial scopal hairs. The male of mackieae differs from that of cerebrata by its broader facial quadrangle (broader than long), the dorsal enclosure of the propodeum being smooth and tessellate, and the sterna having only weakly formed subapical fimbriae.
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