Anthidium mormonum

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Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Anthidiini
Genus: Anthidium Fabricius, 1804
Subgenus: A. (Anthidium) Fabricius, 1804
Species: Anthidium mormonum Cresson, 1878
Common name: none

Overview

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).

Diagnostic characteristics

(modified from Gonzalez and Griswold 2013)

• Female labrum is elevated basally and has two large preapical projections that curve upwards.
• Female mandible has 5–6 teeth.
• Female propodeal triangle is dull and finely lineolate to imbricate.
• Female hind tibia without anterior carina.
• Female T1–T5 discal areas are strongly elevated and weakly shiny between dense punctures.
• Female T1–T5 depressed marginal zones have nearly contiguous punctures.
• Female T1–T5 impunctate apical zones are dull and narrow with doubly carinate margins.
• Female T6 apical rim is distinctly depressed and medially projected.
• Male S4 median apical brush is narrow, with light reddish-brown hairs that can be difficult to see among sternal hairs. The apical margin of S4 is straight medially.
• Male S6 with pointed lateral lobes and a broadly rounded median lobe.
• Male S7 is truncate apically.
• Male S8 apical process is long, narrow, and deeply bifid apically with ventrally bent pointed lobes.
• Male T6 lateral spine is straight, and as long as the T7 median spine.
• Male T7 lateral lobe is apically rounded, and 1.0–1.5 times wider than the distance between the inner margin and median spine.

May be confused with

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).

Phenology

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).

Host associations

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).

Nesting behavior

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).

Distribution

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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