Megachile (Leptorachis)

Taxonomy

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

Overview

Megachile (Leptorachis) have primarily black integument, sometimes with reddish-brown legs, and white, yellow, reddish, black, and gray hairs (Mitchell 1937a; Genaro 1998). They range in body length from 8–16 mm (Michener 2007).

Diagnostic characteristics

(modified from Mitchell 1937a; Mitchell 1943; Michener 2007; Gonzalez 2008)

  • Female mandible four-toothed (can rarely be five-toothed) without a cutting edge in the second interspace and with a complete cutting edge in the third interspace.
  • Female apical tooth is not much broader than the second or third teeth.
  • Female gena is narrower than the eye in lateral view.
  • Female third mandibular tooth is broadly truncate.
  • Female S6 is bare with a bare, smooth rim except for a subapical fringe of hairs, and is not produced.
  • Female T6 is broad apically.
  • Male front coxa has a short, acute spine.
  • Male middle tibial spur is present but small.
  • Male T6 with dense, highly plumose hair.
  • Male T6 lacks discernible teeth on the apical margin.

May be confused with

Megachile (Leptorachis) may be confused with bees in the subgenus Megachile (Pseudocentron). Females in both groups often have a four-toothed mandible with a cutting edge in the third interspace. However, Megachile (Leptorachis) can be differentiated from Megachile (Pseudocentron) by the lack of a cutting edge in the second interspace (Mitchell 1933; Michener 2007; Gonzalez 2008). Male Megachile (Leptorachis) can be distinguished by their small, articulated spur on the middle tibia instead of the fused, immovable prong present in Megachile (Pseudocentron) (Michener 2007).

Host associations

Megachile (Leptorachis) have been observed visiting flowers from a number of plant families, including Acanthaceae, Amaranthaceae, Aquifoliaceae, Asteraceae, Cactaceae, Campanulaceae, Ericaceae, Fabaceae, Haemodoraceae, Hypericaceae, Lamiaceae, Lauraceae, Orobanchaceae, Polygonaceae, Turneraceae, Scrophulariaceae, Verbenaceae, and Vitaceae (Mitchell 1937a; Deyrup et al. 2002; Albuquerque et al. 2007; Santos et al. 2013).

Nesting behavior

Megachile (Leptorachis) build their nests out of leaf fragments and are known to nest in pre-existing cavities (Raw 2004a). In one case, Megachile (Leptorachis) was observed nesting among library books (Raw 2004a).

Diversity

Megachile (Leptorachis) consists of 31 known species (Michener 2007; Gonzalez et al. 2019).

Known invasives

There are no known invasives.

Distribution

Megachile (Leptorachis) are native to North and South America, and range from Argentina to the U.S. (Michener 2007). A majority of this subgenus is found in the tropics, although one species, Megachile (Leptorachis) petulans is found in the U.S. east of the Rocky Mountains and in Arizona (Michener 2007).

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

<p><em>Megachile (Leptorachis) </em>sp female face, photo: Jeni Sidwell</p>
Megachile (Leptorachis) sp female face, photo: Jeni Sidwell
<p><em>Megachile zexmeniae </em>female lateral habitus, photo: Jeni Sidwell</p>
Megachile zexmeniae female lateral habitus, photo: Jeni Sidwell
<p><em>Megachile (Leptorachis)</em> sp. female abdomen, photo: Jeni Sidwell</p>
Megachile (Leptorachis) sp. female abdomen, photo: Jeni Sidwell
<p><em>Megachile colombiana </em>male face, photo: Jeni Sidwell</p>
Megachile colombiana male face, photo: Jeni Sidwell
<p><em>Megachile colombiana </em>male lateral habitus, photo: Jeni Sidwell</p>
Megachile colombiana male lateral habitus, photo: Jeni Sidwell
<p><em>Megachile zexmeniae </em>male abdomen, photo: Jeni Sidwell</p>
Megachile zexmeniae male abdomen, photo: Jeni Sidwell
<p><em>Megachile zexmeniae </em>male lateral, photo: Colleen Meidt</p>
Megachile zexmeniae male lateral, photo: Colleen Meidt
<p><em>Megachile petulans </em>male middle leg, photo: Colleen Meidt</p>
Megachile petulans male middle leg, photo: Colleen Meidt