Family: Megachilidae
Subfamily: Megachilinae
Tribe: Anthidiini
Genus: Anthidium Fabricius, 1804
Subgenus: A. (Anthidium) Fabricius, 1804
Species: Anthidium mormonum Cresson, 1878
Common name: none
Anthidium (Anthidium) mormonum are black with light reddish-brown coloration on the tarsi and yellow maculations (Gonzalez and Griswold 2013). Females have white to light ferruginous pubescence, sometimes with slightly darker coloration on the face, vertex, scutum, axilla, scutellum, inner tarsi, and sides of propodeum. The clypeus and supraclypeal area is covered with erect, simple, apically curved hairs. Females have a body length of 8.0–11.2 mm (Gonzalez and Griswold 2013). Males have dense, brown, short, stout, simple hairs on the ventral surface of the hind coxa. Males range in body length from 7.7–13.0 mm (Gonzalez and Griswold 2013).
(modified from Gonzalez and Griswold 2013)
Female A. mormonum can be easily distinguished from all other Anthidium species in the U.S. by the combination of a distinctly dull propodeum, lack of the anterior carina on the hind tibia, lack of dense tomentum on the outer basitarsi, and depressed apical rim of T6 that is distinctly projected medially. Male A. mormonum can be distinguished from other Anthidium by the combination of apically rounded lateral lobe on T7, acute lateral lobes and broadly rounded median lobe of S6, and reddish-brown, sparse, and indistinct median apical brush of hairs on S4 (Gonzalez and Griswold 2013).
Small specimens of A. mormonum may be confused with A. utahense; however, A. mormonum can be differentiated by the dull propodeal triangle, the shape of T6 in females, and T7 with a rounded lateral lobe in males (Gonzalez and Griswold 2013).
Anthidium mormonum adults have been recorded in flight from March to early September, with peak activity occurring from May to August (Gonzalez and Griswold 2013).
Anthidium mormonum is a generalist that has been observed visiting a variety of species within Apiaceae, Asteraceae, Boraginaceae, Brassicaceae, Cactaceae, Caryophyllaceae, Crassulaceae, Fabaceae, Geraniaceae, Iridaceae, Lamiaceae, Malvaceae, Onagraceae, Phrymaceae, Plantaginaceae, Polemoniaceae, Polygonaceae, Portulacaceae, Rhamnaceae, and Rosaceae (Gonzalez and Griswold 2013).
Anthidium mormonum nest in preexisting cavities in abandoned beetle tunnels in old yucca flower stalks (Agavaceae) and oak stumps (Fagaceae). Each nest has between one and four cells. Nests are comprised of trichomes from Lepidospartum squamatum (Asteraceae). Females have been observed competing over nest space. During this altercation, the females grabbed each other, and attempted to bite and sting each other as they fell to the ground (Hicks 1929).
In the U.S., Anthidium mormonum occur from the Pacific coast to Montana, western South Dakota, western Nebraska, Colorado, and New Mexico. In Canada, they are found in British Columbia. In Mexico, they occur in northern Baja California. They are restricted to forests, Mediterranean California chaparral and woodlands, shrublands, and shrub steppes (Gonzalez and Griswold 2013).
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