Genus: Pseudoanthidium Friese, 1898
Subgenera: Branthidium, Exanthidium, Gnathanthidium, Immanthidium, Mesanthidiellum, Micranthidium, Neanthidium, Pseudoanthidium, Royanthidium, Semicarinella, Tuberanthidium, Zosteranthidium
Common name: none
Pseudoanthidium is a broad group with diverse species ranging from 6–11 mm in body length. Their color varies from having black integument with distinct maculate bands on the abdomen to being entirely black (Michener 2007).
(modified from Litman et al. 2016 unless otherwise stated)
Pseudoanthidium and Afranthidium are very similar genera, with the multi-dentate mandibles in females and similar morphology. Recently several subgenera that were once considered part of the genus Afranthidium were placed in the genus Pseudoanthidium (Litman et al. 2016). Pseudoanthidium differs from Afranthidium by the presence of strongly concave sterna with combs or specialized bristles (Michener 2007).
Pseudoanthidium nanum is native to the western Palearctic region and has been found in the U.S. as early as 2008 in northern New Jersey. Since then, it has been collected in several states between Maryland and Massachusetts (Droege and Shapiro 2011).
Most Pseudoanthidium species are believed to be specialized on flowers in the family Asteraceae, although some may specialize on different tribes and subfamilies within Asteraceae (Müller 1996). There are, however, a few exceptions: P. ochragnathum is known to transition between families within Brassicaceae, Boraginaceae, and Fabaceae (Müller 1996). Pseudoanthidium (Immanthidium) has been seen on Fabaceae, and P. (Branthidium) has been observed visiting flowers in both Fabaceae and Asteraceae (Gess and Gess 2007).
Although nesting habits of most species are unknown, the nesting behavior of P. (Immanthidium) repetitum make it particularly capable of spreading outside its native range. Pseudoanthidium repetitum has been found nesting in electrical boxes, a heavy-duty vice, and electrical adaptors. Its ability to nest in man-made objects is likely how it was introduced to Australia in the 2000s, where it is now common in some areas (Baumann et al. 2016).
Pseudoanthidium are widespread across Africa, Europe, and Asia (Michener 2007). Pseudoanthidium nanum has been introduced to the northeastern U.S. and Australia (Droege and Shapiro 2011).
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