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Andrena congrua LaBerge, 1977
Life   Insecta   Hymenoptera   Apoidea   Andrenidae   Andrena
Subgenus: Psammandrena


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Reprinted with permission of the American Entomological Society from: LaBerge, W. E. 1977. A revision of the bees of the genus Andrena of the Western Hemisphere. Part VIII. Subgenera Thysandrena, Dasyandrena, Psammandrena, Rhacandrena, Euandrena, Oxyandrena. Transactions of the American Entomological Society 103: 1-144.

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This California species is somewhat larger than cercocarpi but is very closely related and difficult to distinguish from the latter. The female of congrua differs from that of cercocarpi by the facial fovea being broader, the triangular area beneath the median ocellus being shiny and the posterior hind tibial spur being strongly curved. The male of congrua can be told from that of cercocarpi by the small depressed area below the median ocellus being shiny and by the less densely tessellate, shinier terga (especially the last three or four terga). Both cercocarpi and congrua are remarkable in having highly disproportionate sex ratios favoring the females. Why so few males have been collected cannot be explained at this time.

FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 8-10 mm width, 2.5-3.0 mm; wing length, M = 3.45 ± 0.076 mm; FL/FW, M = 0.98 ± 0.004; FOVL/FOVW, M = 2.99 ± 0.036.

INTEGUMENTAL COLOR. — Black with same exceptions as in cercocarpi but wing membranes moderately infumate, brownish-yellow.

STRUCTURE. — Antennae as in cercocarpi but flagellar segments 4-7 quadrate, 8 and 9 slightly longer than broad. Eyes, mandible, malar space and galea as in cercocarpi. Maxillary palpus as in cercocarpi but segmental ratio about as 1.0:1.0:0.8:0.8:0.5:0.7. Labial palpus as in cercocarpi but ratio about as 1.0:0.5:0.5:0.6. Labrum as in cercocarpi. Clypeus as in cercocarpi but punctures more evident especially in apical half. Supraclypeal area, genal area and vertex as in cercocarpi. Face above antennal. fossae tessellate with minute rugulae not reaching ocelli; with small depressed shiny triangular area immediately below median ocellus. Facial fovea as in cercocarpi but broader, occupying half space between inner margin compound eye and median ocellus or almost half.

Thoracic form and sculpturing and wing venation as in cercocarpi. Posterior hind tibial spur strongly curved, bowed outwards (much as in Plastandrena but lacking basal expansion).

Metasomal terga as in cercocarpi but tessellation often finer especially on terga 4 and 5. Pygidial plate U-shaped with raised internal triangle (V-shaped when worn). Sterna 2-5 as in cercocarpi.

VESTITURE. — Essentially identical in color and form to that of cercocarpi.

MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 7-10 mm; width, 1.5-2.5 mm; wing length, M = 3.25 ± 0.105 mm; FL/FW, M = 1.04 ± 0.006; FS1/FS2, M = 0.92 ± 0.014.

INTEGUMENTAL COLOR. — Black with same exception as in cercocarpi but flagellum usually dark brown below and wing membranes usually slightly infumate.

STRUCTURE. — Antennae, eyes, malar space, mandible and galea as in cercocarpi. Maxillary palpus as in cercocarpi but segmental ratio about as 1.0:1.0:1.0;0.8:0.7:0.8. Labial palpus as in cercocarpi but ratio about as 1.0:0.5:0.5:0.5. Labrum, clypeus, supraclypeal area, genal area and vertex as in cercocarpi. Face above antennal fossae as in cercocarpi but small depressed triangular area immediately below median ocellus shiny, not at all tessellate nor rugulate.

Thoracic form and sculpturing, wing venation and tibial spurs as in cercocarpi.

Metasomal terga as in cercocarpi but tessellation much finer and minute puncture more evident especially on last three or four terga which are usually moderately shiny. Sterna 2-5 often shiny or moderately so, shagreening weak. Vestigial pygidial plate present. Terminalia as in Figures 82-86.

VESTITURE. — Essentially identical with that of cercocarpi.

Names
Scientific source:

Supported by

Hosts · map
FamilyScientific name @ source (records)
Boraginaceae  Cryptantha intermedia @ UCRC_ENT (2)

Cryptantha @ UCRC_ENT (1)
_  Withheld @ BBSL__YOSE (52); BBSL (12)

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Updated: 2024-03-29 08:56:25 gmt
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