Anthidium utahense

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Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Anthidiini
Genus: Anthidium Fabricius, 1804
Subgenus: A. (Anthidium) Fabricius, 1804
Species: Anthidium utahense Swenk, 1914
Common name: none

Overview

Anthidium (Anthidium) utahense are dark brown to black, with light brown coloration on the tarsi, and yellow maculations (Gonzalez and Griswold 2013). Females have white pubescence except for some light ferruginous to yellow hairs on the vertex, scutum, axilla, scutellum, inner tarsi, and occasionally S6. Females range in body length from 6.2–10.3 mm, and males range in length from 8.5–10.8 mm (Gonzalez and Griswold 2013).

Diagnostic characteristics

(modified from Gonzalez and Griswold 2013)

• Female basitarsi outer surface is covered with sparse tomentum.
• Female clypeus with apically curved hairs.
• Female labrum has two large preapical projections that curve upwards and lacks basal protuberances.
• Female mandible has five teeth.
• Female propodeal triangle is weakly lineolate, smooth, and shiny.
• Female hind tibia without anterior carina.
• Female T1–T5 discal areas are weakly elevated with shiny, smooth areas between coarse, dense punctures.
• Female T1–T5 depressed marginal zones are densely punctate.
• Female T1–T5 apical impunctate areas are narrow, smooth, and shiny with thick, doubly carinate margins.
• Female T6 has small but distinct lateral angles.
• Female T6 preapical carina is absent.
• Male S4 median apical brush narrow with dense, short, reddish-brown hairs.
• Male S4 apical margin is straight medially.
• Male S6 with acute lateral lobes and a broadly rounded median lobe.
• Male S8 has a long, narrow, apically bifid apical process with ventrally pointed lobes.
• Male T6 lateral spine is straight and about as long as T7 median spine.
• Male T7 lateral lobe is subquadrate and twice as broad as the distance between the inner margin and median spine.

May be confused with

Anthidium utahense may be confused with A. jocosum based on the small body size; female basitarsi lacking dense tomentum; shape of the female T6; and shape of male T7, genitalia, and sterna (Gonzalez and Griswold 2013). Female A. utahense can be differentiated from A. jocosum by the broadly truncate apical margin T6 and yellow maculations on the clypeus and paraocular area (Gonzalez and Griswold 2013). Male A. utahense can also be differentiated from A. jocosum by the slightly more developed median apical brush on S4, and the more acute, dark, and sclerotized lateral lobe on S6 (Gonzalez and Griswold 2013).

Phenology

Anthidium utahense adults have been recorded in flight from March to mid-September; however, one specimen was recorded in October. Peak activity occurs from May to July (Gonzalez and Griswold 2013).

Host associations

Anthidium utahense is a generalist that has been observed visiting a variety of species within Alliaceae, Asteraceae, Boraginaceae, Brassicaceae, Cactaceae, Cleomaceae, Crassulaceae, Euphorbiaceae, Fabaceae, Fagaceae, Lamiaceae, Liliaceae, Malvaceae, Onagraceae, Plantaginaceae, Polemoniaceae, Polygonaceae, Portulacaceae, Rhamnaceae, Rosaceae, and Themidaceae (Gonzalez and Griswold 2013).

Nesting behavior

Anthidium utahense nests in holes or crevices in the ground. Each nest has between one and four cells that are comprised of plant trichomes from Cirsium and Artemisia. Nest plugs are constructed with pebbles (Jaycox 1966).

Distribution

Anthidium utahense occur west of the Rocky Mountains in the U.S. (Gonzalez and Griswold 2013). In Mexico, they are found in Baja California. In Canada, they occur in southern British Columbia. They are found primarily in pine-oak forests, the Mojave and Sonoran deserts, California chaparral and woodlands, montane and coastal forests, shrub steppe, and grasslands. Anthidium utahense is very abundant in mediterranean California (Gonzalez and Griswold 2013).

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