Genus: Anthidiellum Cockerell, 1904
Subgenera: Ananthidiellum, Anthidiellum, Chloranthidiellum, Clypanthidium, Loyolanthidium, Pycnanthidium, Ranthidiellum
Common name: none
Anthidiellum is a widespread genus of stocky, robust bees, often with the scutellum produced as broad, truncate lamella that overhangs the metanotum (Michener 2007). They are generally small bees that range in body length from 5–10 mm (Michener 2007). They have black integument with varying amounts of yellow, orange, cream, or red maculations on their head, thorax, and abdomen (Michener 2007).
Anthidiellum contains over 60 described species with multiple species being undescribed. Three species from 1 subgenus, A. (Loyolanthidium), are common in the U.S. (Michener 2007).
(modified from Michener 2007)
North American Anthidiellum can be distinguished from other pollen collecting anthidiines by the combination of arolia present, distinctly arcuate subantennal sutures, and the produced, truncate scutellum that overhangs the metanotum (Michener 2007).
There are no known invasives.
Little is known about the floral resources utilized by Anthidiellum. The North American species appear to be generalists, but some species may prefer Asteraceae (Wilson and Carril 2016).
Anthidiellum are solitary bees that primarily build aerial nests on twigs, branches, and rocks out of resin (Schwarz 1928; Grigarick and Stange 1968; Soh et al. 2016). Anthidiellum (Loyolanthidium) notatum has been observed building nests on crevices of palmetto fronds or hanging from pine needles (Schwarz 1928). Anthidiellum (Pycnanthidium) smithii smithii has been observed in trap nests and line and cap nests. Nest partitions are comprised of resin and an unidentifiable “whitish gummy substance,” presumably a plant gum (Krombein and Norden 2001). In contrast to building aerial nests, members of the subgenus Ranthidiellum excavate subterranean nests in soil. These nests are lined with resin (Pasteels 1972, Pasteels 1977). Two North American Anthidiellum species, A. notatum and A. perplexum, mate where females are foraging on flowers (Turell 1976).
Anthidiellum has a global distribution being found on all continents except Antarctica. Many of the subgenera within Anthidiellum have distinct ranges (Michener 2007).