Megachile (Acentron)

Taxonomy

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

Overview

Megachile (Acentron) albitarsis are black bees with white, yellow, and/or black pubescence (Mitchell 1943). They range in body length from 11–13 mm (Mitchell 1943).

Diagnostic characteristics

(modified from Mitchell 1937a; Mitchell 1943; Gonzalez et al. 2018)

Preoccipital carina absent.
Female gena usually broader than the width of the eye in lateral view.
Female mandible is robust and four-toothed with the second interspace small, nearly absent, and a long cutting edge in the third interspace.
Female S6 is mostly hairless on the disc.
Female T6 is broadly rounded or apically truncate.
Male front coxa with long spine and middle coxa usually with a small spine.
Male front and middle tarsi and tibia modified and expanded.
Male mandible with a strong basal tooth on the lower margin.
Male middle tibia without a tibial spur.

May be confused with

Female Megachile (Acentron) may be confused with female bees within the subgenus Megachile (Leptorachina) with similar four-toothed mandibles with a small second interspace and mostly bare S6. Female Megachile (Acentron) can be differentiated by the wide gena and more robust mandible (Gonzalez 2018). Male Megachile (Acentron) are most similar to Megachile (Melanosarus) because they both lack tibial spurs on the middle legs and the modified front and middle tibia and tarsi. Megachile (Acentron) can be identified by the scutum, which has punctures that are dense enough that the punctures are not individually distinguishable and often by the presence of a spine on the coxa of the mid-leg (Gonzalez et al. 2018).

Host associations

Megachile (Acentron) albitarsis is a generalist that has been observed visiting a variety of species in different plant families including: Anacardiaceae, Apiaceae, Apocynaceae, Arecaceae, Asteraceae, Eriocaulaceae, Fabaceae, Haemodoraceae, Lamiaceae, Orobanchaceae, Plantaginaceae, Polygonaceae, Rubiaceae, Xyridaceae, and Verbenaceae (Mitchell 1937a; Deyrup et al. 2002).

Nesting behavior

Megachile (Acentron) have been found nesting in pre-existing cavities including artificial trap-nests, where they make nest cells using cut leaves (Reyes-Novelo et al. 2009; Hall and Ascher 2010; Torretta et al. 2017; Santos et al. 2020).

Diversity

Megachile (Acentron) includes eighteen species (Moure et al. 2012).

Known invasives

There are no known invasives.

Distribution

Megachile (Acentron) occurs from the southern U.S. to Argentina, the majority of which are found in the tropics. One species, Megachile (Acentron) albitarsis, is native to the U.S. (Michener 2007).

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