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Andrena nigrae Robertson, 1905
Andrena illinoensis form bicolor_homonym Robertson, 1898; Andrena nigrae Robertson, 1905, replacement name; Andrena salicinellina Viereck and Cockerell, 1914; Andrena (Andrena) abacta Viereck, 1917

Life   Insecta   Hymenoptera   Apoidea   Andrenidae   Andrena
Subgenus: Micrandrena

Andrena nigrae, male, face
Smithsonian Institution, Entomology Department · 9
Andrena nigrae, male, face
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Andrena nigrae, male, genitalia
Smithsonian Institution, Entomology Department · 9
Andrena nigrae, male, genitalia
Andrena nigrae, male, side
Smithsonian Institution, Entomology Department · 9
Andrena nigrae, male, side

Andrena nigrae, male, top
Smithsonian Institution, Entomology Department · 9
Andrena nigrae, male, top
Andrena nigrae, male, wing
Smithsonian Institution, Entomology Department · 9
Andrena nigrae, male, wing

Andrena nigrae FEM mm .x f
© Copyright Laurence Packer 2014 · 7
Andrena nigrae FEM mm .x f
Andrena nigrae MALE CFP
© Copyright Laurence Packer 2014 · 7
Andrena nigrae MALE CFP

Andrena nigrae, M, Back, MD, PG County ---.. ZS PMax
© Copyright source/photographer · 5
Andrena nigrae, M, Back, MD, PG County ---.. ZS PMax
Andrena nigrae, M, Face, MD, PG County ---.. ZS PMax
© Copyright source/photographer · 5
Andrena nigrae, M, Face, MD, PG County ---.. ZS PMax

Andrena nigrae, M, Side, Maryland, Anne Arundel County ---.. ZS PMax
© Copyright source/photographer · 5
Andrena nigrae, M, Side, Maryland, Anne Arundel County ---.. ZS PMax
Andrena nigrae, M, Side, MD, PG County ---.. ZS PMax
© Copyright source/photographer · 5
Andrena nigrae, M, Side, MD, PG County ---.. ZS PMax

Andrena nigrae, M. Face, Maryland, Anne Arundel County ---.. ZS PMax
© Copyright source/photographer · 5
Andrena nigrae, M. Face, Maryland, Anne Arundel County ---.. ZS PMax
Andrena nigrae, M, Back, Maryland, Anne Arundel County ---.. ZS PMax
© Copyright source/photographer · 5
Andrena nigrae, M, Back, Maryland, Anne Arundel County ---.. ZS PMax

Andrena nigrae, side
Smithsonian Institution, Entomology Department · 1
Andrena nigrae, side
Overview
Reprinted with permission from the University of Nebraska State Museum from: Ribble, D. W. 1968. Revisions of two subgenera of Andrena, Micrandrena Ashmead and Derandrena new subgenus (Hymenoptera: Apoidea). Bulletin of the University of Nebraska State Museum 8: 1-124.

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I feel that Robertson (1898) intended to give Andrena illinoiensis form bicolor infrasubspecific rank since illinoiensis and its form were probably described from the same locality and since he described Andrena mariae form concolor and Parandrena andrenoides form bicolor in the same paper as illinoiensis form bicolor. Robertson was dealing with color variation. Under the description of Parandrena andrenoides form bicolor where he also discusses illinoiensis, Robertson says “By itself the red color is of no value except as indicating a mere variation form.” In the description of illinoiensis form bicolor he states, “Two female specimens agree with the normal form in all respects except that the abdomen is reddish, .” Robertson (1902) gave his bicolor subspecific status and in 1905, he raised this taxon to a full species and renamed it Andrena nigrae to remove the homonymy with the Fabrician name.

The males (except two specimens, one with a red abdomen) and dark females of nigrae (see below and under Variation) have been confused with illinoiensis and salictaria and have not been recognized as belonging with the red abdomen females which have been considered nigrae. (It is unfortunate that this species received the name nigrae for it is the only Micrandrena with a red abdomen; the specific name refers to Salix nigra.) Many dark specimens bear salictaria and illinoiensis determination labels. A few dark specimens are determined as one of the dark synonyms of nigrae. Mitchell’s (1960) male description of salictaria fits nigrae better than it does salictaria (see salictaria). For discussion of other literature problems see illinoiensis.

The descriptions below are based mainly on a male and a female from Lincoln (7 mi. N), Nebraska, May 9, 1964, D. W. Ribble, on Salix nigra. These specimens are typical of nigrae and were collected near the center of the range of the species. A total of 804 bees of this species were examined.

FEMALE. MEASUREMENTS AND RATIOS. — Length, 7.4 mm; width of mesothorax, 1.9 mm; wing length from tegula, 5.7 mm; facial length/width, 1.07; foveal length/width, 3.50.

INTEGUMENTAL COLOR. — Color as in illinoiensis except: head and thorax with predominant purplish metallic reflections and few deep blue-black reflections; abdomen red (see Variation).

STRUCTURE. — Head as in illinoiensis except: maxillary palpus with segments in ratio of about 1.8:1.8:1.6:1.4:1.0:1.4; labial palpus with segments in ratio of about 2.2:1.4:1.0:1.4; clypeus more heavily shagreened and therefore less shiny; genal area in lateral view nearly as wide as eye.

Mesosoma as in illinoiensis except: posterior hind tibial spur distinctly longer than anterior spur; pterostigma large, nearly twice as wide as prestigma; first transverse cubital vein ending two vein widths from pterostigma.

Metasoma as in illinoiensis.

VESTITURE. — Hairs as in illinoiensis except: facial fovea distinctly chocolate brown; hairs of anterior mesoscutum sparser, shorter and with shorter and fewer branches; apical fasciae interrupted medially on terga 2 and 3; hairs only one-sixth as long as exposed tergal length.

MALE. MEASUREMENTS AND RATIOS. — Length, 7.1 mm; width of mesothorax, 1.9 mm; wing length from tegula, 5.4 mm; facial length/width, 1.04; flagellar segment 1/segment 2, 1.5.

INTEGUMENTAL COLOR. — Color as in illinoiensis except: head and thorax with deep blue-black and purple metallic reflections; tips of tibiae as well as tarsi red-brown.

STRUCTURE. — Head as in illinoiensis except: maxillary palpus with segments in ratio of about 1.2:1.5:1.0:1.2:1.6:1.4; labial palpus with segments in ratio of about 1.6:1.1:1.0:1.5.

Mesosoma as in illinoiensis.

Exposed metasoma as in illinoiensis except: tergum 7 broadly rounded with posterior margin bent slightly upward; sternum 6 with broad apical emargination extending nearly to lateral margin, lateroapical corners gradually and distinctly bend downward.

Sterna 7, 8 and genital capsule as in salictaria except: penis valve not expanded at tip, tapering to narrowly rounded point (fig. 69), tip not extending (or only slightly) past sternum 8 nor visible when in normal position in bee.

VESTITURE. — Hairs as in illinoiensis except: apical abdominal fasciae weaker; tuft of hairs on sternum 6 much less conspicuous.

VARIATION. — Andrena nigrae females have black or red abdomens, and specimens can be found that exhibit all degrees of coloration between these two extremes. Both red and black females occur in Kansas, Illinois, Iowa and Nebraska. In Kansas and Nebraska the two forms have been collected together. In Kansas and Illinois the black form predominates; south and east of Kansas and Illinois only the black form occurs. In Nebraska and Iowa the red form predominates; north and west of Nebraska and Iowa the red (or partially red) form occurs, except that the two specimens examined from Washington and a single specimen from Colorado (no locality given) have black abdomens. I have seen a few males with partially red abdomens.

Some specimens of both sexes have body hairs with a yellowish tinge; these may be young individuals. The margin of the labral process is variable; in the females it may be evenly rounded from side to side, undulating or pointed; in the males the margin is squared or emarginate apically. The female antennae may be orange- or red-brown below or occasionally they may be all brown.



Reprinted with permission from: Mitchell, T.B. 1960. Bees of the Eastern United States. North Carolina Agricultural Experiment Station Technical Bulletin No. 141.

FEMALE. — This answers to the description of illinoiensis in all details except color of abdomen, which is bright ferruginous. Robertson, however, suggested that it is more closely related to salictaria. Eventual recognition of the male will show, possibly, whether this is a subspecies or variant of one of these two closely related species, or is a valid and different species.

DISTRIBUTION. — Illinois, Minnesota; May.

FLOWER RECORDS. — Salix. Robertson (1929) records this also on Antennaria.

Names
Scientific source:

Supported by

Hosts · map
FamilyScientific name @ source (records)
Betulaceae  Alnus @ RUAC_ENT (1)
Brassicaceae  Barbarea vulgaris @ CUIC_ENT (5)
Grossulariaceae  Ribes sp @ BBSL (1)
Polycitoridae  Salix sp @ BBSL (4)
Rosaceae  Potentilla canadensis @ AMNH_BEE (1)
Salicaceae  Salix exigua @ BBSL (1)

Salix sp @ CUIC_ENT (11)

Salix @ RUAC_ENT (1)

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Updated: 2017-06-26 00:44:28 gmt
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