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Andrena tridens Robertson, 1902
Andrena enigmatica Viereck and Cockerell, 1914; Andrena (Gymandrena) bisignata Mitchell, 1960

Life   Insecta   Hymenoptera   Apoidea   Andrenidae   Andrena
Subgenus: Andrena

Andrena tridens, Mid-Atlantic Phenology
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Andrena tridens, Mid-Atlantic Phenology

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Andrena tridens FEM CFP
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Andrena tridens FEM CFP
Andrena tridens MALE CFP
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Andrena tridens MALE CFP

Andrena tridens, figure15f
Mitchell, Bees of the Eastern United States, Vol. I, 1960 · 1
Andrena tridens, figure15f
Andrena tridens, figure16e
Mitchell, Bees of the Eastern United States, Vol. I, 1960 · 1
Andrena tridens, figure16e

Andrena tridens, figure22c
Mitchell, Bees of the Eastern United States, Vol. I, 1960 · 1
Andrena tridens, figure22c
Andrena tridens, figure23c
Mitchell, Bees of the Eastern United States, Vol. I, 1960 · 1
Andrena tridens, figure23c

Andrena tridens, Barcode of Life Data Systems
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Andrena tridens, Barcode of Life Data Systems
Andrena tridens, sternal plates 7 and 8,
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Andrena tridens, sternal plates 7 and 8,

Andrena tridens, face, female
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Andrena tridens, face, female
Andrena tridens, male, head lateral view
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Andrena tridens, male, head lateral view

Andrena tridens, face
Smithsonian Institution, Entomology Department · 1
Andrena tridens, face
Andrena tridens, side
Smithsonian Institution, Entomology Department · 1
Andrena tridens, side

Andrena tridens, top
Smithsonian Institution, Entomology Department · 1
Andrena tridens, top
Andrena tridens, male cheek ridge
Deana Crumbling · 1
Andrena tridens, male cheek ridge
Overview
Reprinted with permission of the American Entomological Society from: LaBerge, W. E. 1980. A revision of the bees of the genus Andrena of the Western Hemisphere. Part X. Subgenus Andrena. Transactions of the American Entomological Society 106: 395-526.

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This small eastern species is readily confused with A. mandibularis and pale specimens of A. thaspii; Mitchell (1960) associated the male described by Robertson (1902) as tridens with females described by Viereck (1907) as cornelli; This left a group of females with associated males without a name and Mitchell described these as bisignata; However, the female of cornelli does not, so far as now known, occur as far west as Illinois and, therefore, tridens could not be its male; Also, the males of bisignata described by Mitchell are indistinguishable from the tridens male of Robertson; however, the females of cornelli and bisignata are very different; It is suggested here that bisignata should be synonymized with tridens as the females and males have been collected together in many areas including Illinois, Nebraska, Kansas and North Carolina; The females of cornelli have been taken with males only a few times and the associated males are not distinguishable from the tridens males; Both sexes of tridens are marked by having basal inferior teeth on the mandibles, by lacking tergal apical pale fasciae and by the extremely short malar space and bidentate labral process; The male of tridens has a much longer first flagellar segment and more coarsely punctate propodeum than males of mandibularis or of thaspii; The female of tridens is marked by a short narrow facial fovea and more or less shiny clypeus.

FEMALE. MEASUREMENTS AND RATIOS. N = 20; length, 9-11 mm; width, 2.5-3.0 mm; wing length, M = 4.12 0.107 mm; FL/FW, M = 1.01 0.006; FOVL/ FOVW, M = 3.64 0.057.

INTEGUMENTAL COLOR. Black except as follows: mandible with apical third to half rufescent; tegula translucent, yellowish-brown; wing membranes slightly infumate, yellowish-brown, veins reddish-brown; tibial spurs testaceous; tarsi dark rufescent; terga with apical areas often with rufescent reflections.

STRUCTURE. Antennal scape length equals first two and one-half flagellar segments or slightly less; flagellar segment 1 as long as following two segments, segment 2 slightly shorter than 3 and about as long as broad; Eyes as in mandibularis; Mandible as in mandibularis but basal inferior tooth weak, often not evident; Malar space short, minimum length about one-fifth width of mandibular base; Galea pointed, outer margin in apical half straight, not concave, surface opaque, tessellate; Maxillary palpus as in frigida with segmental ratio about as 0.8:1.0:0.8:0.7:0.5:0.5; Labial palpus as in frigida but ratio about as 1.0:0.5:0.5:0.6; Labral process trapezoidal, reflexed, shiny, weakly emarginate; labrum apical to process with weak median crista, flat or slightly sulcate, shiny; Clypeus evenly rounded from side to side with distinct, usually broad, median, impunctate line; punctures small to moderate in size, separated mostly by one or more puncture widths apically, more crowded laterally and basally; surface dulled by reticular shagreening in basal third or more, rarely mostly shagreened, usually moderately shiny apicomedially; Supraclypeal area dulled by minute punctures and irregular shagreening; Face above antennal fossae with distinct longitudinal rugulae and interrugal punctures, rugulae usually somewhat convergent toward ocelli; Facial fovea shallow, short, narrow, not extending below level of lower margins antennal fossae, separated from lateral ocellus by one ocellar diameter or more; Vertex short, above lateral ocellus equal to one ocellar diameter or slightly less; surface opaque, tessellate with scattered punctures; Genal area in profile slightly broader than eye; surface dull to moderately so, reticularly shagreened with minute punctures separated by one to two or more puncture widths.

Pronotum as in frigida but moderately shiny posterior to ridge; Mesoscutum dulled by fine tessellation, punctures obscure but visible, separated by half to one puncture width; Scutellum similar but punctures crowded posteriorly; Metanotum opaque, tessellate with contiguous punctures; Propodeum with dorsal enclosure irregularly roughened in basal half or more, finely tessellate; dorsal area outside of enclosure and posterior surface dulled by fine tessellation and distinct crowded punctures; lateral surface moderately shiny, tessellation coarse, with scattered large shallow punctures, usually with irregular fine rugulae in posterior third or more; Mesepisternum dull, tessellate with distinct shallow punctures separated mostly by half a puncture width or less in upper half, sparser below.

Metasomal terga 1-5 sculptured as in mandibularis; Pygidial plate broad, apex blunt, internal raised triangular area present; Sterna 2-5 sculptured as in frigida.

VESTITURE. White to pale ochraceous except as follows: facial fovea with short internal hairs brown; terga 5 and 6 with long hairs pale brown medially; tarsi with inner surfaces pale yellow; vestiture with form and distribution as in mandibularis but tibial scopal hairs slightly sparser.

MALE. MEASUREMENTS AND RATIOS. N = 20; length, 6.5-10.0 mm; width, 1.5-2.5 mm; wing length, M = 3.42 0.166 mm; FL/FW, M = 0.98 0.009; FS1/FS2, M = 1.52 0.029.

INTEGUMENTAL COLOR. Black with some exceptions as female but tergal apical areas usually slightly translucent, rufescent.

STRUCTURE. Antennae moderately long; scape length equals slightly more than first two flagellar segments; flagellar segment 1 about one and one-half times longer than segment 2 which is shorter than segment 3 and as long as broad or slightly longer; Eyes and mandibles as in mandibularis; Malar space short, one-fifth as long as width of mandibular base (excluding inferior tooth); Galea as in female; Maxillary palpus as in female but segmental ratio about as 0.8:1.0:0.8:0.7:0.6:0.6; Labial palpus as in female but ratio about as 1.0:0.8:0.6:0.6; Labral process weakly bidentate, reflexed, shiny; labrum apical to process shiny, without cristae; Clypeus as in mandibularis; Supraclypeal area and face above antennal fossae as in female; Vertex moderately tall, above lateral ocellus usually equal to about one ocellar diameter, sculptured as in female; Genal area broad, in profile at least twice width of eye, angulate posteriorly; surface moderately dulled by reticular shagreening and minute sparse punctures.

Pronotum as in mandibularis; Mesoscutum and scutellum as in female; Propodeum as in female but dorsal surface outside of enclosure and posterior surface with punctures more distinct and abundant, lateral surface with punctures forming irregular ridges or rugulae in posterior third or more.

Metasomal terga sculptured as in female; Tergum 7 without pygidial-like area; Sterna 2-5 sculptured as in frigida; Sternum 6 flat, weakly emarginate apically.

Terminalia as in figures 72-76.

VESTITURE. White or pale ochraceous except a few brown hairs on face between upper thirds of compound eyes or near inner margins compound eyes and inner surfaces tarsi pale yellow; vestiture form and distribution as in mandibularis but sterna 2-5 with subapical fimbriae slightly shorter.




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

FEMALE Length 10 mm.; face somewhat longer than distance between eyes; clypeus somewhat convex, almost as long as broad, produced considerably below suborbital line, dull and tessellate, the punctures scattered, irregular and obscure; facial foveae narrow, occupying above only slightly more than half of space between eyes and lateral ocelli, the tomentum slightly yellowish; lateral ocelli separated from margin of vertex by a space about equal to their diameter; cheeks slightly broader than eyes, smooth, minutely punctate; malar space very short; basal segment of flagellum subequal to 2nd and 3rd combined; process of labrum much broader than long, subtriangular, the tip truncate, slightly emarginate; mandibles of moderate length, with a small subapical inner tooth; pubescence of head, thorax and base of abdomen entirely pale, slightly yellowish above, of moderate length and density; thoracic integument dull and tessellate, with shallow and rather close punctures on scutum and on pleura above, scutellum nearly impunctate, shining; enclosure of propodeum finely rugose toward basal margin; propodeal corbicula rather thin, anterior fringe poorly developed; trochanteral floccus rather thin; tibial scopa thin, composed of long, simple, sparse hairs; hind tibiae slender and elongate, all the basitarsi somewhat narrower than their respective tibiae; 2nd submarginal cell shorter than 3rd, receiving 1st recurrent close to the tip; abdominal terga dull and tessellate, impunctate except for some very minute, obscure punctures toward base, apical margins very slightly impressed, concolorous with the remainder of the discs, discal pubescence very short, entirely pale and thin, apical margins with rather thin, but distinctly evident, white fasciae.

MALE Length 8-9 mm.; clypeus rather flattened, much broader than long, somewhat shining medially where the punctures are fine and sparse, becoming closer toward sides; lateral ocelli separated from margin of vertex by a space about equal to their diameter; cheeks very broad and flat, with a subcarinate, rounded, posterior angle opposite upper part of eye, surface shining, minutely punctate; malar space very short; basal segment of flagellum slightly shorter than 2nd and 3rd combined; process of labrum subtriangular, the apex narrowed, truncate and slightly incised; mandibles slender and elongate, slightly flexed medially, with a small subapical inner tooth, the base with a ventral subtriangular projection; pubescence of head, thorax and base of abdomen entirely pale, slightly ochraceous; thoracic integument dull, tessellate, with rather close, shallow and obscure punctures on scutum and upper portions of pleura, scutellum more shining, nearly impunctate; enclosure of propodeum subrugose toward base; all basitarsi slender and elongate, considerably narrower than their respective tibiae; 2nd submarginal cell much shorter than 3rd, receiving 1st recurrent toward tip; abdominal terga smooth, but dull and tessellate, without evident punctures, apical margins very slightly depressed, largely dark, pubescence entirely pale, very thin, without evident fasciae; apical portion of sternum 8 narrow, elongate, parallel-sided, tip beyond the subapical ridge slightly broader than long, truncate apically; penis valves expanded basally, excavated beneath this expansion on each side, gonocoxites only narrowly dilated apically, gonocoxal lobes produced, narrowly rounded.

DISTRIBUTION Illinois and Michigan, east to New York and the New England states, south to Tennessee, North Carolina and Georgia; March to July.

FLOWER RECORDS Azalea, Hydrangea, Rhododendron and Rhus. Also recorded by Robertson (1929) on Dentaria and Hepatica.


Described using the synonymous name: Andrena bisignata Mitchell

FEMALE. Length 10 mm.; clypeus slightly convex, produced well below suborbital line, rather dull laterally, shining medially, with a median impunctate line, with numerous shallow, well separated punctures on each side of this line; facial foveae narrow, occupying above only about half of space between eyes and lateral ocelli, covered with brownish tomentum; space between margin of vertex and lateral ocelli about equal to their diameter; cheeks broader than eyes, rather smooth, minutely and obscurely punctate; malar space distinct, but rather short; basal segment of flagellum subequal to 2nd and 3rd combined; process of labrum subtriangular, about twice as broad as long, tip truncate; mandibles of ordinary length, with a definite, inner, subapical tooth; pubescence of head, thorax and base of abdomen rather long, erect and dense, pure white; thoracic integument dull, densely tessellate, scutum very closely and finely punctate, punctures of scutellum obscure; enclosure of propodeum subrugose along basal margin; propodeal corbicula rather short, anterior fringe rather poorly developed; trochanteral floccus well developed; tibial scopa white, long and quite dense, of simple hairs; hind tibiae narrow and elongate, mid and hind basitarsi slightly narrower than their respective tibiae; 2nd submarginal cell shorter than 3rd, receiving 1st recurrent vein near apex; abdominal terga smooth, dull, nearly impunctate except for some very obscure fine punctures toward base, apical margins slightly depressed, more or less reddened along rims, pubescence thin, erect, entirely white, fasciae inevident.

MALE. Length 7.5 mm.; clypeus produced well below suborbital line, slightly convex, median area flattened, narrowed to apical margin, quite smooth and sparsely and minutely punctate medially, becoming more closely and deeply punctate laterally; space between lateral ocelli and margin of vertex about equal to their diameter; cheeks broad, somewhat shining, minutely and rather sparsely punctate, angulate posteriorly, angle opposite upper third of eye (as in tridens, fig. 21); malar space well developed; basal segment of flagellum subequal to each of the following segments; process of labrum quite small, subtriangular, tip truncate; mandibles narrow and elongate, somewhat flexed medially, overlapping nearly one-half, with a distinct inner subapical tooth and a basal triangular ventral projection; pubescence of head, thorax and base of abdomen long and loose, entirely pale, slightly yellowish above, more whitish below; thoracic integument dull, tessellate; scutum, scutellum and pleura above with shallow, obscure punctures; enclosure of propodeum smooth; all basitarsi slender and elongate, much narrower than their respective tibiae; 2nd submarginal cell much shorter than 3rd, receiving 1st recurrent vein near apex; abdominal terga smooth, rather dull, with very sparse, minute and obscure punctures, apical margins only slightly depressed, rims faintly reddened, pubescence entirely pale, fasciae not developed; apical portion of sternum 8 narrow but rather short, tip beyond subapical ridge broader than long, truncate apically; penis valves expanded basally, excavated on each side beneath this expansion, gonocoxites broadly dilated apically, gonocoxal lobes produced and broadly rounded.

TYPES. Holotype: Female, Forest Hills, Mass., May 4, 1912 (Viereck). Allotype: Topotypical, Apr. 28, 1911 (Viereck) [both A.N.S.P.]. Paratypes: MASSACHUSETTS: 1 M, topotypical, May 14, 1912; 1 M, Cohasset, Apr. 14, 1917 (A. M. Wilcox); 1 F, Essex, Apr. 19, 1920; 1 M, Framingham, Apr. 19, 1920 (Frost); 1 M, Amherst, Apr. 30, 1920 (Mitchell). NEW HAMPSHIRE: 1 M, Jaffrey, June. NEW YORK: 2 MM, Ithaca, Apr. 16, 1916; 1 F, Owego, Apr. 24, 1935 (H. K. Townes). WEST VIRGINIA: 4 FF, Milville, Apr. 2, 1921 (J. C. Bradley); 1 F, Cranberry Glades, June 1, 1955 (H. V. Weems, Jr., on Ilex verticellata). RHODE ISLAND: 3 FF, Kingston, May 12, 1904. MICHIGAN: 1 F, Ann Arbor, Washlenaw Co., May 5, 1949 (U. N. Lanham). NORTH CAROLINA 1 M, Asheville, Apr. 15, 1938; 1 F ,Wilkes Co., April 10, 1952 (W. A. Stephen, on apple); 2 FF, Moravian Falls, Apr. 13, 1954 (W. A. Stephen, on apple); 1 F, Raleigh, Mar. 23, 1923 (Mitchell on Salix). MINNESOTA: 1 F, Mille Lacs, Drow Wing Co., May 18, 1940 (Milliron); 8 MM, Ramsey Co., May 8, 12 & 14, 1952 (R. L. Fischer, on Prunus serotina, Viburnum acerifolium and Pyrus malus); 1 M, St., Anthony Park, Ramsey Co., May 12, 1952 (Fischer). VIRGINIA: 1 F, Vienna, April 18, 1915; 1 F, Savage Sta., April 14, 1917 (both W. L. McAtee, on Erythronium americanum); 1 F, Mount Vernon, April 16, 1916 (A. Wetmore, on Salix sericea). MARYLAND: 2 FF, Laurel, April 6 & 13, 1919 (W. L. McAtee, on Salix).

Paratypes listed above are located in the Museum of Comparative Zoology, the University of Minnesota, the University of Rhode Island, Cornell University, the U. S. National Museum, the North Carolina Department of Agriculture, in personal collections of R. R. Dreisbach, R. L. Fischer, H. K. Townes, and H. V. Weems, Jr., and in the author's collection.


Names
Scientific source:

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Hosts · map
FamilyScientific name @ source (records)
Boraginaceae  Mertensia @ AMNH_BEE (1)
Ericaceae  Andromeda @ AMNH_BEE (1)

Azalea sp @ BBSL (1)
Hydrangeaceae  Hydrangea sp @ BBSL (1)
Liliaceae  Erythronium @ AMNH_BEE (2)
Rosaceae  Prunus @ AMNH_BEE (3)
Salicaceae  Salix humilis @ AMNH_BEE (1)
_  apple @ NLA (6)

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