Anthidium schwarzi

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Anthidiini
Genus: Anthidium Fabricius, 1804
Subgenus: A. (Anthidium) Fabricius, 1804
Species: Anthidium schwarzi Gonzalez and Griswold, 2013
Common name: none

Overview

Anthidium (Anthidium) schwarzi are dark brown to black with yellow maculations (Gonzalez and Griswold 2013). Females have white to yellowish pubescence, except for the brown hairs found on the middle tibia, inner tarsi, and S1. Females range in body length from 9.1–11.5 mm (Gonzalez and Griswold 2013). Male pubescence is lighter than that of females. Males range in body length from 11.5–14.3 mm (Gonzalez and Griswold 2013).

Diagnostic characteristics

(modified from Gonzalez and Griswold 2013)

  • Female labrum has two large preapical projections that point upwards but lack basal protuberances.
  • Female mandible has 5–6 teeth.
  • Female propodeal triangle is weakly lineolate and shiny.
  • Female hind tibia without anterior carina.
  • Female T1T5 discal areas are slightly elevated, dull, and weakly imbricate between punctures.
  • Female T6 lacks a preapical carina.
  • Female T6 has a strong lateral spine, a small median emargination, and a depressed apical rim that projects laterally into a submedian lobe.
  • Male labrum preapical projections are larger than in females.
  • Male S4 with median apical brush of long, dense, black apical hairs.
  • Male S4 apical margin is concave medially.
  • Male S6 lateral lobes are short and broad, and median lobe is sub-rectangular and notched medially.
  • Male S7 distal margin is concave.
  • Male S8 apical process is diamond-shaped, and strongly curved ventrally in profile.
  • Male T6 lateral spine is straight and as long as T7 median spine.
  • Male T7 lateral lobe is elongate and rounded apically.

May be confused with

Female A. schwarzi may be confused with A. palmarum due to the combination of basitarsi covered with dense tomentum and T6 with distinct sublateral lobes (Gonzalez and Griswold 2013). Female A. schwarzi can be differentiated from A. palmarum by the presence of distinct lateral spines on T6 and the reduced or absent yellow markings on the face and mandibles (Gonzalez and Griswold 2013). Male A. schwarzi can be differentiated from A. palmarum by the rounded lateral lobes of T7, S7 with a concave apical margin, and a more curved apical process on S8. Male A. schwarzi may be also confused with A. collectum due to the shape of T7 with narrowly rounded lateral lobes; S4 with a concave apical margin and a median apical brush of dense black hairs; and S6 with a median, small, apically notched lobe (Gonzalez and Griswold 2013). Male A. schwarzi can be differentiated from male A. collectum by broader lateral lobes on T7 and a more concave distal margin of S4 with longer hairs on the S4 median apical brush (Gonzalez and Griswold 2013).

Phenology

Anthidium schwarzi adults have been recorded in flight from April to early July, with peak activity occurring from April to May (Gonzalez and Griswold 2013).

Host associations

Anthidium schwarzi is a generalist that has been observed visiting a variety of species within Asteraceae, Boraginaceae, Fabaceae, and Malvaceae (Gonzalez and Griswold 2013). However, A. schwarzi has such a strong preference for Phacelia (Boraginaceae) that it may be a specialist (Gonzalez and Griswold 2013).

Nesting behavior

Nesting behavior is unknown.

Distribution

Anthidium schwarzi occur in the U.S. throughout northern Arizona, southern Nevada, New Mexico, western Texas, and Utah. In Mexico, they can be found in Sonora. They are found in the Chihuahuan Desert, Colorado Plateau shrublands, Western short grasslands, and occasionally in the Great Basin and eastern Mojave Desert (Gonzalez and Griswold 2013).


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

<p><em>Anthidium schwarzi</em> female face, photo: Chelsey Ritner</p>
Anthidium schwarzi female face, photo: Chelsey Ritner
<p><em>Anthidium schwarzi</em> female lateral habitus, photo: Chelsey Ritner</p>
Anthidium schwarzi female lateral habitus, photo: Chelsey Ritner
<p><em>Anthidium schwarzi</em> female abdomen, photo: Chelsey Ritner</p>
Anthidium schwarzi female abdomen, photo: Chelsey Ritner
<p><em>Anthidium schwarzi</em> male face, photo: Chelsey Ritner</p>
Anthidium schwarzi male face, photo: Chelsey Ritner
<p><em>Anthidium schwarzi</em> male lateral habitus, photo: Chelsey Ritner</p>
Anthidium schwarzi male lateral habitus, photo: Chelsey Ritner
<p><em>Anthidium schwarzi</em> male abdomen, photo: Chelsey Ritner</p>
Anthidium schwarzi male abdomen, photo: Chelsey Ritner
<p><em>Anthidium schwarzi</em> male, ventral view of fourth sternum (S4), photo from Gonzalez and Griswold 2013</p>
Anthidium schwarzi male, ventral view of fourth sternum (S4), photo from Gonzalez and Griswold 2013
<p><em>Anthidium schwarzi</em> male, dorsal view of seventh tergum (T7), photo: Chelsey Ritner</p>
Anthidium schwarzi male, dorsal view of seventh tergum (T7), photo: Chelsey Ritner
<p><em>Anthidium schwarzi</em> male, diagram showing dorsal view of seventh tergum (T7), diagram from Gonzalez and Griswold 2013</p>
Anthidium schwarzi male, diagram showing dorsal view of seventh tergum (T7), diagram from Gonzalez and Griswold 2013
<p><em>Anthidium schwarzi</em> male, diagram showing ventral view of sixth sternum (S6), diagram from Gonzalez and Griswold 2013</p>
Anthidium schwarzi male, diagram showing ventral view of sixth sternum (S6), diagram from Gonzalez and Griswold 2013
<p><em>Anthidium schwarzi</em> male, diagram showing ventral view of seventh sternum (S7), diagram from Gonzalez and Griswold 2013</p>
Anthidium schwarzi male, diagram showing ventral view of seventh sternum (S7), diagram from Gonzalez and Griswold 2013
<p><em>Anthidium schwarzi</em> male, diagram showing ventral view of eighth sternum (S8), diagram from Gonzalez and Griswold 2013</p>
Anthidium schwarzi male, diagram showing ventral view of eighth sternum (S8), diagram from Gonzalez and Griswold 2013
<p><em>Anthidium schwarzi </em>male dorsal genital, photo from Gonzalez and Griswold 2013</p>
Anthidium schwarzi male dorsal genital, photo from Gonzalez and Griswold 2013