Megachile (Dasymegachile)

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Megachilini
Genus: Megachile Latreille, 1802
Subgenus: Dasymegachile Mitchell, 1943
Common name: none

Overview

Megachile (Dasymegachile) is a subgenus of robust bees with black integument that is usually covered in long, dense hair that does not form apical bands of hair on the terga. Females have entirely black scopa (Durante et al. 2006; Michener 2007). They range in body length from 10–15 mm (Michener 2007).

Diagnostic characteristics

(modified from Durante et al. 2006; Michener 2007; Gonzalez 2008)

  • Female mandible four-toothed, with an incomplete cutting edge in the second interspace and a complete cutting edge in the third interspace.
  • Female mandible with upper tooth acute or right-angled.
  • Female scopa black, without apical bands of hair on the sterna beneath.
  • Male antennal segments F1 and F2 are nearly equal in length.
  • Male front coxa without a spine.
  • Male mandible three-toothed, although the middle tooth is sometime notched which can cause it to appear four-toothed.
  • Male mandible without an inferior projection.

May be confused with

Megachile (Dasymegachile) and Megachile (Cressoniella) are similarly sized and both have four-toothed mandibles with cutting edges in the second and third interspaces (Raw 2007; Gonzalez 2008). However, female Megachile (Dasymegachile) have mandibles with an acute or right-angular upper tooth, whereas Megachile (Cressoniella) have an upper tooth which is rounded, truncate, or incised (Michener 2007). Male Megachile (Dasymegachile) antennal segments F1 and F2 are about the same length and mandibles are three-toothed (occasionally the middle tooth is notched). In contrast Megachile (Cressoniella) have an F1 that is shorter than F2, and a four-toothed mandible (Gonzalez 2008).  

Host associations

Through both observation records and pollen analysis, a number of plant families have been recorded as floral resources of Megachile (Dasymegachile), including Alstroemeriaceae, Apiaceae, Asteraceae, Aizoaceae, Boraginaceae, Cactaceae, Fabaceae, Lamiaceae, Loasaceae, Onagrariaceae, Resedaceae, and Scrophulariaceae (Durante et al. 2006).

Nesting behavior

Bees in Megachile (Dasymegachile) build nests from cut leaves or petals in existing cavities (Montalva et al. 2012). Nesting location preferences vary by species. Megachile semirufa, a high-altitude species, builds nests under flat rocks in the Andes Mountains (Montalva et al. 2012). Megachile joergenseni nests in plant material and has been observed nesting in galls (of Duvana dependens), bamboo, and in the canes used for thatched roofs (Montalva et al. 2012; Raw 2007). Megachile saulcyi nests in cavities in walls or soil and will also reuse old nests made by potter wasps (Eumeninae) and thread-waisted wasps (Sphecidae) (Montalva et al. 2012; Raw 2007).

Diversity

Megachile (Dasymegachile) consists of fifteen species (Ascher and Pickering 2020); none are known to occur in the U.S. or Canada.

Known invasives

There are no known invasives. 

Distribution

Megachile (Dasymegachile) is a South American subgenus most commonly found at high altitudes in the Andes mountain range. Their range extends from southern Argentina and Chile northward to Peru and Brazil (Michener 2007; Raw 2007; Gonzalez 2008).

Distribution
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<p><em>Megachile sauleyi </em>female face, photo: Brooke Bagot</p>
Megachile sauleyi female face, photo: Brooke Bagot
<p><em>Megachile sauleyi </em>female lateral habitus, photo: Brooke Bagot</p>
Megachile sauleyi female lateral habitus, photo: Brooke Bagot
<p><em>Megachile sauleyi </em>female abdomen, photo: Brooke Bagot</p>
Megachile sauleyi female abdomen, photo: Brooke Bagot
<p><em>Megachile sauleyi </em>male face, photo: Brooke Bagot</p>
Megachile sauleyi male face, photo: Brooke Bagot
<p><em>Megachile sauleyi </em>male lateral habitus, photo: Brooke Bagot</p>
Megachile sauleyi male lateral habitus, photo: Brooke Bagot
<p><em>Megachile sauleyi </em>male abdomen, photo: Brooke Bagot</p>
Megachile sauleyi male abdomen, photo: Brooke Bagot