Chelostomoides

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Megachilini
Genus: Chelostomoides Robertson, 1901
Common name: none

Overview

Chelostomoides are narrow bees, often with black integumentintegument:
a tough, protective outer layer
and contrasting pale apicalapical:
near or at the apex or end of any structure
bands on the 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 7–17 mm (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). This group was elevated from a subgenus of Megachile to genus status by Gonzalez et al. (2019).

Diagnostic characteristics

(modified from Mitchell 1937bMitchell 1937b:
Mitchell, T.B. 1937. A revision of the genus Megachile in the Nearctic region. Part VIII. Taxonomy of the subgenus Chelostomoides, addenda and index (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 63: 381-421.; 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 F1 is shorter than the pedicelpedicel:
  the second segment of the antennae, between the scape and flagellum
  .
• Female mandiblemandible:
  bee teeth, so to speak, usually crossed and folded in front of the mouth
  is highly variable but lacks a cutting edge.
• 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
  with dense, uniform hairs.
• Female tarsal claws without basalbasal:
  originating at the foundation of a structure
  teeth.
• Female 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
  basalbasal:
  originating at the foundation of a structure
  grooves are covered in pale hairs.
• Male mandiblemandible:
  bee teeth, so to speak, usually crossed and folded in front of the mouth
  is three-toothed.

May be confused with

Chelostomoides may be confused with bees within Megachile (Chelostomoda) due to having similar size, body shape, and postgradular grooves (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). Chelostomoides, however, have hairs in the postgradular grooves, lack cutting edges on their mandibles, and the females of some species have a highly modified clypeusclypeus:
a section of the face below the antennae, demarcated by the epistomal sutures
(Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). These bees, while similar morphologically, have very different distributions: Chelostomoides is native to the Americas and Chelostomoda to Australia and Asia.

Host associations

Chelostomoides has been observed visiting flowers within the plant families of Aquifoliaceae, Asteraceae, Boraginaceae, Cactaceae, Campanulaceae, Clethraceae, Eriocaulaceae, Fabaceae, Haemodoraceae, Hypericaceae, Lamiaceae, Malvaceae, Onagraceae, Orobanchaceae, Papaveraceae, Plantaginaceae, Polygalaceae, Polygonaceae, Verbenaceae, and Zygophyllaceae (Mitchell 1937bMitchell 1937b:
Mitchell, T.B. 1937. A revision of the genus Megachile in the Nearctic region. Part VIII. Taxonomy of the subgenus Chelostomoides, addenda and index (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 63: 381-421.; Deyrup et al. 2002Deyrup et al. 2002:
Deyrup, M., Edirisinghe, J. and Norden, B. 2002. The diversity and floral hosts of bees at the Archbold Biological Station, Florida (Hymenoptera: Apoidea). Insecta Mundi 16: 87-120, 544.).

Nesting behavior

Chelostomoides nest in pre-existing cavities; they have been recorded nesting in abandoned beetle burrows, in cavities in wood, twigs, and stems, and in nail holes and holes in walls (Armbrust 2004Armbrust 2004:
Armbrust, E.A. 2004. Resource use and nesting behavior of Megachile prosopidis and M. chilopsidis with notes on M. discorhina (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 77(2): 89-98.; Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). Most of these bees collect plant resins to build their nests, although M. discorhina produces a secretion that it uses as an adhesive instead of using resins (Armbrust 2004Armbrust 2004:
Armbrust, E.A. 2004. Resource use and nesting behavior of Megachile prosopidis and M. chilopsidis with notes on M. discorhina (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 77(2): 89-98.). Chelostomoides use a variety of other materials in nest construction, including sand, pebbles, chewed leaves, and small pieces of wood (Armbrust 2004Armbrust 2004:
Armbrust, E.A. 2004. Resource use and nesting behavior of Megachile prosopidis and M. chilopsidis with notes on M. discorhina (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 77(2): 89-98.; Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). The composition of the nest plugs in particular can vary significantly, even between members of the same species (Armbrust 2004Armbrust 2004:
Armbrust, E.A. 2004. Resource use and nesting behavior of Megachile prosopidis and M. chilopsidis with notes on M. discorhina (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 77(2): 89-98.; Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). These plugs create a barrier between the opening of the cavity and the nest cells and can consist of a single layer of resin or a series of several layers of different materials (Armbrust 2004Armbrust 2004:
Armbrust, E.A. 2004. Resource use and nesting behavior of Megachile prosopidis and M. chilopsidis with notes on M. discorhina (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 77(2): 89-98.).

Diversity

Chelostomoides contains thirty-three species (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.; Raw 2007Raw 2007:
Raw, A. 2007. An annotated catalogue of the leafcutter and mason bees (genus Megachile ) of the Neotropics. Zootaxa 1601: 1-127.; Gonzalez et al. 2019Gonzalez et al. 2019:
Gonzalez, V.H., G.T. Gustafson, and M.S. Engel. 2019. Morphological phylogeny of Megachilini and the evolution of leaf-cutter behavior in bees (Hymenoptera: Megachilidae). Journal of Melittology (85): 1-123.).

Known invasives

There are no known invasives in the U.S. However, Chelostomoides otomita, which is native to the U.S., has become established in the Canary Islands, a Spanish archipelago off the western coast of Africa (Strudwick and Jacobi 2018Strudwick and Jacobi 2018:
Strudwick, T. and B. Jacobi. 2018. The American resin bee Chelostomoides otomita Cresson, 1878 established on Tenerife, Canary Islands (Spain) (Hymenoptera, Anthophila). Ampulex 10: 41-45.).

Distribution

Chelostomoides are native to North America and northern South America. In North America, they have a transcontinental range with the northern boundary extending from British Columbia, Canada to New York (Giles and Ascher 2006Giles and Ascher 2006:
Giles, V. and J.S. Ascher. 2006. A survey of the bees of the Black Rock Forest Preserve, New York (Hymenoptera: Apoidea). Journal of Hymenoptera Research 15: 208ndash;231.; 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 widespread south of this boundary, including throughout the Caribbean Islands, Mexico, and Central America to South America, where they have been recorded in Colombia and Peru (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.).

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References

Armbrust, E.A. 2004. Resource use and nesting behavior of Megachile prosopidis and M. chilopsidis with notes on M. discorhina (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 77(2): 89-98.

Deyrup, M., Edirisinghe, J. and Norden, B. 2002. The diversity and floral hosts of bees at the Archbold Biological Station, Florida (Hymenoptera: Apoidea). Insecta Mundi 16: 87-120.

Giles, V. and J. S. Ascher. 2006. A survey of the bees of the Black Rock Forest preserve, New York (Hymenoptera: Apoidea). Journal of Hymenoptera Research 15(2): 208-231. 

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.

Gonzalez, V.H., G.T. Gustafson, and M.S. Engel. 2019. Morphological phylogeny of Megachilini and the evolution of leaf-cutter behavior in bees (Hymenoptera: Megachilidae). Journal of Melittology (85): 1-123.

Krombein, K.V. 1967. Trap-nesting wasps and bees: life histories, nests, and associates. Washington, DC Smithsonian Institution Press: 570 pp.

Medler, J.T. 1966. A resin bee using trap-nests in Wisconsin, and a note on other resin bees (Hymenoptera: Megachilidae). Entomological News 77: 228-230.

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. Classifaction 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 VIII. Taxonomy of the subgenus Chelostomoides, addenda and index (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 63: 381-421.

Strudwick, T. and B. Jacobi. 2018. The American resin bee Chelostomoides otomita Cresson, 1878 established on Tenerife, Canary Islands (Spain) (Hymenoptera, Anthophila). Ampulex 10: 41-45.

Raw, A. 2007. An annotated catalogue of the leafcutter and mason bees (genus Megachile) of the Neotropics. Zootaxa 1601: 1-127.