Atoposmia

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Osmiini
Genus: Atoposmia Cockerell, 1935
Subgenera: Atoposmia, Eremosmia, Hexosmia
Common name: none

Overview

Atoposmia are robust bees that range in body length from 5.5–9 mm (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). They typically have black bandsbands:
usually referring to bands of hair or bands of color that traverse across an abdominal segment
with white bandsbands:
usually referring to bands of hair or bands of color that traverse across an abdominal segment
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
, and white or off-white hair on the face and thorax (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). Members of the subgenus Hexosmia have a slightly metallic green coloration on the head, thorax, and abdomen (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.).

Diversity

Atoposmia contains approximately 30 species that are known from North America (Hurd and Michener 1955Hurd and Michener 1955:
Hurd, P.D. and C.D. Michener. 1955. Megachiline Bees of California (Hymenoptera: Megachilidae). Bulletin of the California Insect Survey (Vol. 3). Berkeley and Los Angeles: University of California Press, 247 pp.; Wilson and Carril 2016Wilson and Carril 2016:
Wilson, J.S. and O.M. Carril. 2016. The Bees in Your Backyard: A Guide to North Americarsquo;s Bees. Princeton University Press, Princeton and Oxford, 288 pp.).

Diagnostic characteristics

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

• Arolia present.
• Mesopleuron short ventrally, much shorter than the length of the scutumscutum:
  the large segment on top of the thorax located between the wings and behind the head
  .
• Middle tibiatibia:
  the segment of the leg, between the femur and the tarsus
  with one apicalapical:
  near or at the apex or end of any structure
  spine.
• Omaulus omaulus:
  angle between anterior and lateral surfaces of mesepisternum
  not carinatecarinate:
  having keels or carinae
  .
• Parapsidal lines linear and 1/3 – 1/2 as long as the tegulategula:
  the usually oval, small shield-like structure carried at the extreme base of the wing where it attaches to the body
  .
• Pronotal lobes lack carinacarina:
  a clearly defined ridge or keel, not necessarily high or acute; usually appears on bees as simply a raised line
  .
• T1 with anterioranterior:
  toward the head or on the head side of a segment being described
  surface broadly concave.
• Female tarsal claws simple.
• Male S2S2:
  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
  larger than S3S3:
  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
  .
• Male S3S3:
  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
  broadly emarginated.
• Male T6T6:
  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
  with laterallateral:
  relating, pertaining, or attached to the side
  teeth, except in subgenus Hexosmia.

May be confused with

Atoposmia may be confused with Hoplitis and Ashmeadiella due to their similar dark-colored bodies with relatively stocky builds. Ashmeadiella has a carinatecarinate:
having keels or carinae
omaulus which differentiates it from Atoposmia, while Hoplitis are often more slender, and the males have basalbasal:
originating at the foundation of a structure
flaps on 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
(Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.).

Known invasives

There are no known invasives.

Host associations

Most species of Atoposmia are specialists on Penstemon spp. (Michener 1949; Crosswhite and Crosswhite 1966Crosswhite and Crosswhite 1966:
Crosswhite, F.S. and C.D. Crosswhite. 1966. Insect pollinators of Penstemon series Graciles (Scrophulariaceae) with notes on Osmia and other Megachilidae. American Midland Naturalist 76: 450ndash;467.; Tepedino et al. 2007Tepedino et al. 2007:
Tepedino, V.J., T.R. Toler, B.A. Bradley, J.L. Hawk, and T.L. Griswold. 2007. Pollination biology of a disjunct population of the endangered sandhills endemic Penstemon haydenii S. Wats. (Scrophulariaceae) in Wyoming, USA. Plant Ecology, 193: 59ndash;69.; Wilson et al. 2010Wilson et al. 2010:
Wilson, J.S., L.E. Wilson, L.D. Loftis, and T. Griswold. 2010. The montane bee fauna of north central Washington, USA, with floral associations. Western North American Naturalist, 70: 198ndash;207.; Scott et al. 2011Scott et al. 2011:
Scott, V.L., J.S. Ascher, T. Griswold, and C.R. Nufio. 2011. The bees of Colorado. Natural History Inventory of Colorado, 23, pp.1ndash;100.).

Nesting behavior

Some members of subgenus Atoposmia make nests under rocks or in rock crevices as single cell clusters. Nest partitions are comprised of masticated plant material with the occasional inclusion of sand (Parker 1975Parker 1975:
Parker, F.D. 1975. Nests of the mason bees Osmia tanneri Sandhouse and O. longula Cresson with a description of the female of O. tanneri. Pan-Pacific Entomologist 51: 179ndash;183., 1977). Members of subgenus Eremosmia can be found nesting in hollow stems or in the soil, where they construct nests of masticated plant material, soil, or a combination of the two reinforced with nectar (Parker 1975Parker 1975:
Parker, F.D. 1975. Nests of the mason bees Osmia tanneri Sandhouse and O. longula Cresson with a description of the female of O. tanneri. Pan-Pacific Entomologist 51: 179ndash;183., 1977; Yanega 1994Yanega 1994:
Yanega, D. 1994. Nests and hosts of three species of megachild bees (Hymenoptera: Apoidea: Megachilidae) from Coahuila, Meacute;xico. Journal of the Kansas Entomological Society 67: 415ndash;417.). Members within the subgenus Hexosmia nest in stems, with cell walls built out of chewed plant material with the occasional inclusion of sand (Parker 1975Parker 1975:
Parker, F.D. 1975. Nests of the mason bees Osmia tanneri Sandhouse and O. longula Cresson with a description of the female of O. tanneri. Pan-Pacific Entomologist 51: 179ndash;183.).

Distribution

Atoposmia is endemic to North America and occurs from British Colombia, Canada to Puebla, Mexico (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). They are most diverse in the western U.S., especially in montane environments (subgenus Atoposmia) and deserts (subgenus Eremosmia). A few species occur eastward to west Texas and Oklahoma (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.; Wilson and Carril 2016Wilson and Carril 2016:
Wilson, J.S. and O.M. Carril. 2016. The Bees in Your Backyard: A Guide to North Americarsquo;s Bees. Princeton University Press, Princeton and Oxford, 288 pp.). In the US, they are predominantly spring bees, while in Mexico, they fly in the fall (Wilson and Carril 2016Wilson and Carril 2016:
Wilson, J.S. and O.M. Carril. 2016. The Bees in Your Backyard: A Guide to North Americarsquo;s Bees. Princeton University Press, Princeton and Oxford, 288 pp.).

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References

Hurd, P.D. and C.D. Michener. 1955. Megachiline bees of California (Hymenoptera: Megachilidae). Bulletin of the California Insect Survey 3: 1-247.

Crosswhite, F.S. and C.D. Crosswhite. 1966. Insect pollinators of Penstemon series Graciles (Scrophulariaceae) with notes on Osmia and other Megachilidae. American Midland Naturalist 76: 450-467.

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

Parker, F.D. 1975. Nests of the mason bees Osmia tanneri Sandhouse and O. longula Cresson with a description of the female of O. tanneri. Pan-Pacific Entomologist 51: 179-183.

Parker, F.D. 1977. Nests of Anthocopa enceliae (Cockerell) and A. elongate (Michener). Pan-Pacific Entomologist 55: 47-52.

Scott, V.L., J.S. Ascher, T. Griswold, and C.R. and Nufio. 2011. The bees of Colorado. Natural History Inventory of Colorado, 23, pp.1-100.

Tepedino, V.J., T.R. Toler, B.A. Bradley, J.L. Hawk, and T.L.Griswold. 2007. Pollination biology of a disjunct population of the endangered sandhills endemic Penstemon haydenii S. Wats. (Scrophulariaceae) in Wyoming, USA. Plant Ecology, 193: 59-69.

Wilson, J.S., L.E. Wilson, L.D. Loftis, and T. Griswold. 2010. The montane bee fauna of north central Washington, USA, with floral associations. Western North American Naturalist, 70: 198-207.