Megachile (Cressoniella)

Taxonomy

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

Overview

Megachile (Cressoniella) are medium-sized bees with black integumentintegument:
a tough, protective outer layer
and often with dense long hair that may or may not form pale apicalapical:
near or at the apex or end of any structure
bands hair 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 9–15 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 1935aMitchell 1935a:
Mitchell, T.B. 1935. A revision of the genus Megachile in the Nearctic region. Part II. Morphology of the male sternites and genital armature and the taxonomy of the subgenera Litomegachile, Neomegachile and Cressoniella (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 61: 1-44.; Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.)

• Female F1 is longer 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 four-toothed, with the upper tooth truncatetruncate:
  ending abruptly, or squared off
  and often notched, sometimes giving the appearance of being five-toothed.
• Female mandiblemandible:
  bee teeth, so to speak, usually crossed and folded in front of the mouth
  with a complete cutting edge in the second interspace and a complete cutting edge in the third interspace.
• Female tarsal claws with thickened, tooth-like basalbasal:
  originating at the foundation of a structure
  setae.
• Female 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
  is straight in profile with distinct, erect hairs.
• Male front coxacoxa:
  the basal segment of the leg
  not spined.
• Male fore tarsitarsi:
  the group of segments at the end of the leg following the tibia
  are not expanded or modified.
• Male mandiblemandible:
  bee teeth, so to speak, usually crossed and folded in front of the mouth
  is four-toothed and lacks an inferior projection.
• 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
  preapicalpreapical:
  referring to a section of a bee that is physically found just before the outermost (or apical) end of the section or segment
  carinacarina:
  a clearly defined ridge or keel, not necessarily high or acute; usually appears on bees as simply a raised line
  forming two often spine-like projections.

May be confused with

Megachile (Cressoniella) is a sister group to the subgenus Megachile (Dasymegachile), and they have species with similar sizes and hair patterns. Females are four-toothed in both subgenera, but the inner tooth of Megachile (Cressoniella) is truncatetruncate:
ending abruptly, or squared off
or notched, whereas it is acute in Megachile (Dasymegachile). Males of Megachile (Cressoniella) can be differentiated by their four-toothed mandibles and the lack of a spine on their front coxacoxa:
the basal segment of the leg
.

Host associations

Megachile (Cressoniella) is known to visit plants in the families Aizoaceae, Asteraceae, Asclepiadaceae, Fabaceae, Lamiaceae, Onagraceae, and Solanaceae (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.; Raw 2007Raw 2007:
Raw, A. 2007. An annotated catalogue of the leafcutter and mason bees (genus Megachile ) of the Neotropics. Zootaxa 1601: 1-127.).

Nesting behavior

Megachile (Cressoniella) are leaf-cutter bees and use cut pieces of leaves to build their nest cells (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.). One species, Megachile (Cressoniella) grandibarbis, has been found nesting in old beetle burrows in dead branches and in the soil using the leaves of the genus Nothofagus to build its nest cells (Raw 2007Raw 2007:
Raw, A. 2007. An annotated catalogue of the leafcutter and mason bees (genus Megachile ) of the Neotropics. Zootaxa 1601: 1-127.).

Diversity

Megachile (Cressoniella) consists of twenty-one species (Raw 2007Raw 2007:
Raw, A. 2007. An annotated catalogue of the leafcutter and mason bees (genus Megachile ) of the Neotropics. Zootaxa 1601: 1-127.). Megachile (Cressoniella) zapoteca is the only species that occurs in the U.S. (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.).

Known invasives

There are no known invasives.

Distribution

Megachile (Cressoniella) ranges from Arizona in the southern U.S. south to Argentina. They are predominantly found in xericxeric:
a very dry habitat
environments, but several species are found in high altitudes within the Andes (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 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.).

​Distribution map generated by Discover Life -- click on map for details, credits, and terms of use.

References

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, 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.

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

Mitchell, T.B. 1935. 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 II. Morphology of the male sternites and genital armature and the taxonomy of the subgenera Litomegachile, Neomegachile and Cressoniella (Hymenoptera: Megachilidae). Transactions of the American Entomological Society 61: 1-44.

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