Megachile (Argyropile)

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Megachilini
Genus: Megachile Latreille, 1802
Subgenus: Argyropile Mitchell, 1934
Common name: none

Overview

Megachile (Argyropile) often have a black integumentintegument:
a tough, protective outer layer
with white, tan, or reddish hairs throughout their body, usually forming apicalapical:
near or at the apex or end of any structure
bands of hair on their tergaterga:
the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
(Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). They range in body length from 9–16 mm (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.; Gonzalez 2008Gonzalez 2008:
Gonzalez, V.H. 2008. Phylogeny and classification of the bee tribe Megachilini (Hymenoptera: Apoidea: Megachilidae), with emphasis on the genus Megachile. Thesis: Department of Ecology and Evolutionary Biology and the College of Liberal Arts and Science of the University of Kansas: 1-274.).

Diagnostic characteristics

(modified from Mitchell 1937aMitchell 1937a:
Mitchell, T.B. 1937. A revision of the genus Megachile in the Nearctic region. Part VI. Taxonomy of the subgenera Argyropile, Leptorachis, Pseudocentron, Acentron, and Melanosarus. Transactions of the American Entomological Society 63: 45-83.; Mitchell 1943Mitchell 1943:
Mitchell, T.B. 1943. On the classification of neotropical Megachile (Hymenoptera: Megachilidae). Annals of the Entomological Society of America 36: 656-97.; Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.; Gonzalez 2008Gonzalez 2008:
Gonzalez, V.H. 2008. Phylogeny and classification of the bee tribe Megachilini (Hymenoptera: Apoidea: Megachilidae), with emphasis on the genus Megachile. Thesis: Department of Ecology and Evolutionary Biology and the College of Liberal Arts and Science of the University of Kansas: 1-274.)

• Female mandiblemandible:
  bee teeth, so to speak, usually crossed and folded in front of the mouth
  is four-toothed with the inner tooth sometimes incised, which can give it the appearance of five teeth. The cutting edge between the second and third teeth is shorter and narrower than the edge between the third and fourth teeth, which is evenly concave.
• Female S6S6:
  the plates on the underside of the abdomen, often abbreviated when referring to a specific segment to S1, S2, S3, S4, S5, S6, S7, or S8
  apicalapical:
  near or at the apex or end of any structure
  rim is angled upwards and is either thick or rolled.
• Female S6S6:
  the plates on the underside of the abdomen, often abbreviated when referring to a specific segment to S1, S2, S3, S4, S5, S6, S7, or S8
  is mostly bare rim behind a fringe of preapicalpreapical:
  referring to a section of a bee that is physically found just before the outermost (or apical) end of the section or segment
  hairs.
• Male antenna with apicalapical:
  near or at the apex or end of any structure
  segment unmodified and not expanded.
• Male front tarsitarsi:
  the group of segments at the end of the leg following the tibia
  are simple, slender, and dark-colored or fuscousfuscous:
  gray-brown coloration, generally used to describe wing color
  .
• Male front coxal spine is small and slender and lacks an anterioranterior:
  toward the head or on the head side of a segment being described
  patch of red hairs at the base.
• Male gonoforcepsgonoforceps:
  the unsegmented apical-most appendage of the external male genitalia
  are narrowed above the base, slender, apicallyapically:
  near or at the apex or end of any structure
  compressed, and shorter than the penis valve.
• Male mandiblemandible:
  bee teeth, so to speak, usually crossed and folded in front of the mouth
  with small inferior process.
• Male S6S6:
  the plates on the underside of the abdomen, often abbreviated when referring to a specific segment to S1, S2, S3, S4, S5, S6, S7, or S8
  apicalapical:
  near or at the apex or end of any structure
  margin has acute median teeth and conspicuous laterallateral:
  relating, pertaining, or attached to the side
  teeth.

May be confused with

Female Megachile (Argyropile) may be confused with bees within the subgenera Megachile (Pseudocentron) and Megachile (Acentron) because the female S6S6:
the plates on the underside of the abdomen, often abbreviated when referring to a specific segment to S1, S2, S3, S4, S5, S6, S7, or S8
mostly lacks hair and the apicalapical:
near or at the apex or end of any structure
edge is bent upwards (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.; Gonzalez 2008Gonzalez 2008:
Gonzalez, V.H. 2008. Phylogeny and classification of the bee tribe Megachilini (Hymenoptera: Apoidea: Megachilidae), with emphasis on the genus Megachile. Thesis: Department of Ecology and Evolutionary Biology and the College of Liberal Arts and Science of the University of Kansas: 1-274.). However, Megachile (Argyropile) has a thick apicalapical:
near or at the apex or end of any structure
rim, while the other two subgenera have thinner and translucent rims (Gonzalez 2008Gonzalez 2008:
Gonzalez, V.H. 2008. Phylogeny and classification of the bee tribe Megachilini (Hymenoptera: Apoidea: Megachilidae), with emphasis on the genus Megachile. Thesis: Department of Ecology and Evolutionary Biology and the College of Liberal Arts and Science of the University of Kansas: 1-274.). Megachile (Argyropile) also has a fully developed middle tibial spurtibial spur:
apical projection(s) often found at the apex of the tibia
, whereas Megachile (Pseudocentron) lack the middle tibial spurs and have an immovable prong or tooth instead (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). All three subgenera differ in their mandibularmandibular:
near the mandible
structure.

Host associations

Megachile (Argyropile) are generalists and have been observed visiting a variety of species within Asclepiadaceae, Asteraceae, Bignoniaceae, Brassicaceae, Capparaceae, Fabaceae, Hydrophyllaceae, Hypericaceae, Lamiaceae, Malphighiaceae, Malvaceae, Onagraceae, Polemoniaceae, Polygonaceae, Rhamnaceae, Rubiaceae, Sapindaceae, Tamariaceae, Verbenaceae, and Zygophyllaceae (Butler 1965Butler 1965:
Butler, G.D. 1965. Distribution and host plants of leaf-cutter bees in Arizona. The Technical Bulletin of the Agricultural Experiment Station of University of Arizona 167: 1-19.; Gonzalez and Griswold 2007Gonzalez and Griswold 2007:
Gonzalez, V.H. and Griswold, T.L. 2007. A review of the North and Central American Megachile subgenus Argyropile Mitchell (Hymenoptera: Megachilidae). Zootaxa 1461: 1-14.; Gonzalez 2008Gonzalez 2008:
Gonzalez, V.H. 2008. Phylogeny and classification of the bee tribe Megachilini (Hymenoptera: Apoidea: Megachilidae), with emphasis on the genus Megachile. Thesis: Department of Ecology and Evolutionary Biology and the College of Liberal Arts and Science of the University of Kansas: 1-274.). However, Megachile (Argyropile) shows a preference for Asteraceae (Mitchell 1937aMitchell 1937a:
Mitchell, T.B. 1937. A revision of the genus Megachile in the Nearctic region. Part VI. Taxonomy of the subgenera Argyropile, Leptorachis, Pseudocentron, Acentron, and Melanosarus. Transactions of the American Entomological Society 63: 45-83.; Gonzalez 2008Gonzalez 2008:
Gonzalez, V.H. 2008. Phylogeny and classification of the bee tribe Megachilini (Hymenoptera: Apoidea: Megachilidae), with emphasis on the genus Megachile. Thesis: Department of Ecology and Evolutionary Biology and the College of Liberal Arts and Science of the University of Kansas: 1-274.).

Nesting behavior

Megachile (Argyropile) have been observed nesting in trap nests and burrowing shallow nests in the ground, particularly in sandy soil (Fischer 1951Fischer 1951:
Fischer, R.L. 1951. Observations on the nesting habitats of megachilid bees. Journal of the Kansas Entomological Society 24: 46-50.; Butler 1965Butler 1965:
Butler, G.D. 1965. Distribution and host plants of leaf-cutter bees in Arizona. The Technical Bulletin of the Agricultural Experiment Station of University of Arizona 167: 1-19.; Medler and Lussenhop 1968Medler and Lussenhop 1968:
Medler, J.T. and J.F. Lussenhop. 1968. Leafcutter bees of Wisconsin (Hymenoptera: Megachilidae). Research Bulletin, College of Agricultural and Life Sciences, The University of Wisconsin 274: 1-80.; Neff and Simpson 1991Neff and Simpson 1991:
Neff, J.L. and B.B. Simpson. 1991. Nest biology and mating behavior of Megachile fortis in Central Texas (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 64: 324-336.). The nests are lined with leaves, some of which were identified as Spiraea (Rosaceae) or Trifolium (Fabaceae) (Fischer 1951Fischer 1951:
Fischer, R.L. 1951. Observations on the nesting habitats of megachilid bees. Journal of the Kansas Entomological Society 24: 46-50.).

Diversity

Megachile (Argyropile) is a subgenus of seven species, five of which are found in the U.S. (Gonzalez 2008Gonzalez 2008:
Gonzalez, V.H. 2008. Phylogeny and classification of the bee tribe Megachilini (Hymenoptera: Apoidea: Megachilidae), with emphasis on the genus Megachile. Thesis: Department of Ecology and Evolutionary Biology and the College of Liberal Arts and Science of the University of Kansas: 1-274.).

Known invasives

There are no known invasives. 

Distribution

Megachile (Argyropile) occur throughout North and Central America. They are distributed from southwest Canada to Costa Rica (Mitchell 1937aMitchell 1937a:
Mitchell, T.B. 1937. A revision of the genus Megachile in the Nearctic region. Part VI. Taxonomy of the subgenera Argyropile, Leptorachis, Pseudocentron, Acentron, and Melanosarus. Transactions of the American Entomological Society 63: 45-83.; Gonzalez 2008Gonzalez 2008:
Gonzalez, V.H. 2008. Phylogeny and classification of the bee tribe Megachilini (Hymenoptera: Apoidea: Megachilidae), with emphasis on the genus Megachile. Thesis: Department of Ecology and Evolutionary Biology and the College of Liberal Arts and Science of the University of Kansas: 1-274.).

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References

Butler, G.D. 1965. Distribution and host plants of leaf-cutter bees in Arizona. College of Agriculture, University of Arizona (Tucson, AZ).

Fischer, R.L. 1951. Observations on the nesting habitats of megachilid bees. Journal of the Kansas Entomological Society 24: 46-50.

Gonzalez, V.H. and Griswold, T.L. 2007. A review of the North and Central American Megachile subgenus Argyropile Mitchell (Hymenoptera: Megachilidae). Zootaxa 1461: 1-14.

Gonzalez, V.H. 2008. Phylogeny and classification of the bee tribe Megachilini (Hymenoptera: Apoidea: Megachilidae), with emphasis on the genus Megachile. Thesis: Department of Ecology and Evolutionary Biology and the College of Liberal Arts and Science of the University of Kansas: 1-274.

Medler, J.T. and J.F. Lussenhop. 1968. Leafcutter bees of Wisconsin (Hymenoptera: Megachilidae). Research Bulletin, College of Agricultural and Life Sciences, The University of Wisconsin 274: 1-80.

Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.

Mitchell, T.B. 1933. A revision of the genus Megachile in the NearcticNearctic:
biogeographical region comprising North America as far south as northern Mexico, together with Greenland
region. Part I. Classification and descriptions of new species (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 59: 295-361.

Mitchell, T.B. 1937. A revision of the genus Megachile in the NearcticNearctic:
biogeographical region comprising North America as far south as northern Mexico, together with Greenland
region. Part VI. Taxonomy of the subgenera Argyropile, Leptorachis, Pseudocentron, Acentron, and Melanosarus. Transactions of the American Entomological Society 63: 45-83.

Mitchell, T.B. 1943. On the classification of neotropicalNeotropical:
biogeographic region that includes South and Central America, the Caribbean Islands, southern Florida, and the southern Mexican lowlands
Megachile (Hymenoptera: Megachilidae). Annals of the Entomological Society of America 36: 656-971

Neff, J.L. and B.B. Simpson. 1991. Nest biology and mating behavior of Megachile fortis in central Texas (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 64: 324-336.