Anthidium placitum

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Anthidiini
Genus: Anthidium Fabricius, 1804
Subgenus: A. (Anthidium) Fabricius, 1804
Species: Anthidium placitum Cresson, 1879
Common name: none

Overview

Anthidium (Anthidium) placitum 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 yellow hairs on the vertex, scutum, axilla, scutellum, and inner tarsi. The clypeus is covered in simple, hooked, or wavy hairs. Females range in body length from 11.5–13.8 mm, and males range in length from 10.0–14.6 mm (Gonzalez and Griswold 2013).

Diagnostic characteristics

(modified from Gonzalez and Griswold 2013)

  • Female labrum is weakly elevated basally with two large preapical projections that curve upwards.
  • Female mandible has five teeth.
  • Female propodeal triangle is dull or weakly shiny and finely lineolate.
  • Female hind tibia without anterior carina.
  • Female T1T5 discal areas are weakly elevated with shiny, weakly lineolate to smooth areas between punctures.
  • Female T1T5 depressed marginal zones are uniformly punctate.
  • Female T1T5 impunctate apical zones are narrow, and the margins are doubly carinate.
  • Female T6 with a laterally projected blunt tooth.
  • Female T6 preapical carina is absent.
  • Male S4 median apical brush is narrow with red hairs that can be difficult to see among other hairs on the sternum.
  • Male S6 with medially directed lateral lobes and a subtriangular median lobe.
  • Male S7 with a truncate apical margin.
  • Male S8 has a long, narrow, bifid apical process.
  • Male T6 lateral spine is slightly curved to straight and about as long as T7 median spine.
  • Male T7 lateral lobe is broadly rounded and almost twice as broad as the distance between the inner margin and median spine.

May be confused with

Female A. placitum may be confused with A. edwardsii because of the clypeus covered in hooked or wavy hairs that are emarginate apically (Gonzalez and Griswold 2013). However, female A. placitum can be differentiated from A. edwardsii by T6 with blunt lateral teeth and dense tomentum on the basitarsi (Gonzalez and Griswold 2013). Male A. placitum can be differentiated from A. edwardsii by the broad lateral lobe on T7 (Gonzalez and Griswold 2013).

Phenology

Anthidium placitum adults have been recorded in flight from April to September, with peak activity occurring from the last half of June to September. One specimen was recorded in October (Gonzalez and Griswold 2013).

Host associations

Anthidium placitum is a generalist that has been observed visiting a variety of species within Asteraceae, Boraginaceae, Chenopodiaceae, Cleomaceae, Fabaceae, Grossulariaceae, Lamiaceae, Orobanchaceae, Plantaginaceae, Polemoniaceae, and Polygonaceae (Gonzalez and Griswold 2013).

Nesting behavior

Nesting behavior is unknown.

Distribution

Anthidium placitum occur from California, Oregon, Colorado, Arizona, and southern Washington to western South Dakota in the U.S. (Gonzalez and Griswold 2013). In Mexico, they are found in northern Baja California in the mountains. They are found primarily in shrub steppe, Colorado Plateau shrublands, and California chaparral, woodlands, and forests (Gonzalez and Griswold 2013).


​Distribution map generated by Discover Life -- click on map for details, credits, and terms of use.

<p><em>Anthidium placitum</em> female face, photo: Jeni Sidwell</p>
Anthidium placitum female face, photo: Jeni Sidwell
<p><em>Anthidium placitum</em> female lateral habitus, photo: Jeni Sidwell</p>
Anthidium placitum female lateral habitus, photo: Jeni Sidwell
<p><em>Anthidium placitum</em> female abdomen, photo: Jeni Sidwell</p>
Anthidium placitum female abdomen, photo: Jeni Sidwell
<p><em>Anthidium placitum</em> female, diagram showing the dorsal view of the sixth tergite (T6), diagram from Gonzalez and Griswold 2013</p>
Anthidium placitum female, diagram showing the dorsal view of the sixth tergite (T6), diagram from Gonzalez and Griswold 2013
<p><em>Anthidium placitum</em> male face, photo: Jeni Sidwell</p>
Anthidium placitum male face, photo: Jeni Sidwell
<p><em>Anthidium placitum</em> male lateral habitus, photo: Jeni Sidwell</p>
Anthidium placitum male lateral habitus, photo: Jeni Sidwell
<p><em>Anthidium placitum</em> male abdomen, photo: Jeni Sidwell</p>
Anthidium placitum male abdomen, photo: Jeni Sidwell
<p><em>Anthidium placitum</em> male, ventral view of fourth sternum (S4), photo from Gonzalez and Griswold 2013</p>
Anthidium placitum male, ventral view of fourth sternum (S4), photo from Gonzalez and Griswold 2013
<p><em>Anthidium placitum</em> male, dorsal view of seventh tergum (T7), photo: Jeni Sidwell</p>
Anthidium placitum male, dorsal view of seventh tergum (T7), photo: Jeni Sidwell
<p><em>Anthidium placitum</em> male, diagram showing dorsal view of seventh tergum (T7), diagram from Gonzalez and Griswold 2013</p>
Anthidium placitum male, diagram showing dorsal view of seventh tergum (T7), diagram from Gonzalez and Griswold 2013
<p><em>Anthidium placitum</em> male, diagram showing ventral view of sixth sternum (S6), diagram from Gonzalez and Griswold 2013</p>
Anthidium placitum male, diagram showing ventral view of sixth sternum (S6), diagram from Gonzalez and Griswold 2013
<p><em>Anthidium placitum</em> male, diagram showing ventral view of seventh sternum (S7), diagram from Gonzalez and Griswold 2013</p>
Anthidium placitum male, diagram showing ventral view of seventh sternum (S7), diagram from Gonzalez and Griswold 2013
<p><em>Anthidium placitum</em> male, diagram showing ventral view of eighth sternum (S8), diagram from Gonzalez and Griswold 2013</p>
Anthidium placitum male, diagram showing ventral view of eighth sternum (S8), diagram from Gonzalez and Griswold 2013