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 tarsitarsi:
the group of segments at the end of the leg following the tibia
and yellow maculations (Gonzalez and Griswold 2013Gonzalez and Griswold 2013:
Gonzalez, V.H. and T.L. Griswold. 2013. Wool carder bees of the genus Anthidium in the Western Hemisphere (Hymenoptera: Megachilidae): diversity, host plant associations, phylogeny, and biogeography. Zoological Journal 168: 221ndash;425.). Females have white pubescencepubescence:
short, fine hair
except for yellow hairs on the vertexvertex:
the area between the ocelli and the back of the head
, scutumscutum:
the large segment on top of the thorax located between the wings and behind the head
, axillaaxilla:
the triangular or rounded point on the thorax where thoracic muscles meet the forewing of an insect
, scutellumscutellum:
shield shaped plate behind scutum
, and inner tarsitarsi:
the group of segments at the end of the leg following the tibia
. The clypeusclypeus:
a section of the face below the antennae, demarcated by the epistomal sutures
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 2013Gonzalez and Griswold 2013:
Gonzalez, V.H. and T.L. Griswold. 2013. Wool carder bees of the genus Anthidium in the Western Hemisphere (Hymenoptera: Megachilidae): diversity, host plant associations, phylogeny, and biogeography. Zoological Journal 168: 221ndash;425.).

Diagnostic characteristics

(modified from Gonzalez and Griswold 2013Gonzalez and Griswold 2013:
Gonzalez, V.H. and T.L. Griswold. 2013. Wool carder bees of the genus Anthidium in the Western Hemisphere (Hymenoptera: Megachilidae): diversity, host plant associations, phylogeny, and biogeography. Zoological Journal 168: 221ndash;425.)

• Female labrumlabrum:
  part of the head abutting the clypeus, folds down in front of the mouthparts
  is weakly elevated basally with two large preapicalpreapical:
  referring to a section of a bee that is physically found just before the outermost (or apical) end of the section or segment
  projections that curve upwards.
• Female mandiblemandible:
  bee teeth, so to speak, usually crossed and folded in front of the mouth
  has five teeth.
• Female propodealpropodeal:
  the last segment of the thorax
  triangle is dull or weakly shiny and finely lineolatelineolate:
  marked with fine lines
  .
• Female hind tibiatibia:
  the segment of the leg, between the femur and the tarsus
  without anterioranterior:
  toward the head or on the head side of a segment being described
  carina.
• Female T1–T5 discal areas are weakly elevated with shiny, weakly lineolatelineolate:
  marked with fine lines
  to smooth areas between punctures.
• Female T1–T5 depressed marginal zones are uniformly punctatepunctate:
  studded with tiny holes
  .
• Female T1–T5 impunctateimpunctate:
  marked with punctures or pits
  apicalapical:
  near or at the apex or end of any structure
  zones are narrow, and the margins are doubly carinatecarinate:
  having keels or carinae
  .
• Female T6T6:
  the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
  with a laterally projected blunt tooth.
• Female T6T6:
  the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
  preapicalpreapical:
  referring to a section of a bee that is physically found just before the outermost (or apical) end of the section or segment
  carinacarina:
  a clearly defined ridge or keel, not necessarily high or acute; usually appears on bees as simply a raised line
  is absent.
• Male S4S4:
  the plates on the underside of the abdomen, often abbreviated when referring to a specific segment to S1, S2, S3, S4, S5, S6, S7, or S8
  median apicalapical:
  near or at the apex or end of any structure
  brush is narrow with red hairs that can be difficult to see among other hairs on the sternum.
• Male S6S6:
  the plates on the underside of the abdomen, often abbreviated when referring to a specific segment to S1, S2, S3, S4, S5, S6, S7, or S8
  with medially directed laterallateral:
  relating, pertaining, or attached to the side
  lobes and a subtriangular median lobe.
• Male S7S7:
  the plates on the underside of the abdomen, often abbreviated when referring to a specific segment to S1, S2, S3, S4, S5, S6, S7, or S8
  with a truncatetruncate:
  ending abruptly, or squared off
  apicalapical:
  near or at the apex or end of any structure
  margin.
• Male S8S8:
  the plates on the underside of the abdomen, often abbreviated when referring to a specific segment to S1, S2, S3, S4, S5, S6, S7, or S8
  has a long, narrow, bifidbifid:
  divided into two branches; forked
  apicalapical:
  near or at the apex or end of any structure
  process.
• Male T6T6:
  the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
  laterallateral:
  relating, pertaining, or attached to the side
  spine is slightly curved to straight and about as long as T7T7:
  the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
  median spine.
• Male T7T7:
  the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
  laterallateral:
  relating, pertaining, or attached to the side
  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. edwardsiibecause of the clypeusclypeus:
a section of the face below the antennae, demarcated by the epistomal sutures
covered in hooked or wavy hairs that are emarginateemarginate:
a notched or cut out place in an edge or margin, can be dramatic or simply a subtle inward departure from the general curve or line of the margin or structure being described
apicallyapically:
near or at the apex or end of any structure
(Gonzalez and Griswold 2013Gonzalez and Griswold 2013:
Gonzalez, V.H. and T.L. Griswold. 2013. Wool carder bees of the genus Anthidium in the Western Hemisphere (Hymenoptera: Megachilidae): diversity, host plant associations, phylogeny, and biogeography. Zoological Journal 168: 221ndash;425.). However, female A. placitum can be differentiated from A. edwardsii by T6T6:
the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
with blunt laterallateral:
relating, pertaining, or attached to the side
teeth and dense tomentumtomentum:
a form of pubescence composed of short matted, woolly hair
on the basitarsibasitarsi:
the segment of the tarsus that is the nearest to the body of the bee, usually the largest of all the tarsal segments
(Gonzalez and Griswold 2013Gonzalez and Griswold 2013:
Gonzalez, V.H. and T.L. Griswold. 2013. Wool carder bees of the genus Anthidium in the Western Hemisphere (Hymenoptera: Megachilidae): diversity, host plant associations, phylogeny, and biogeography. Zoological Journal 168: 221ndash;425.). Male A. placitum can be differentiated from A. edwardsiiby the broad laterallateral:
relating, pertaining, or attached to the side
lobe on T7T7:
the segments on the top side of the abdomen, often abbreviated when referring to a specific segment to T1, T2, T3, T4, T5, T6, or T7
(Gonzalez and Griswold 2013Gonzalez and Griswold 2013:
Gonzalez, V.H. and T.L. Griswold. 2013. Wool carder bees of the genus Anthidium in the Western Hemisphere (Hymenoptera: Megachilidae): diversity, host plant associations, phylogeny, and biogeography. Zoological Journal 168: 221ndash;425.).

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 2013Gonzalez and Griswold 2013:
Gonzalez, V.H. and T.L. Griswold. 2013. Wool carder bees of the genus Anthidium in the Western Hemisphere (Hymenoptera: Megachilidae): diversity, host plant associations, phylogeny, and biogeography. Zoological Journal 168: 221ndash;425.).

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 2013Gonzalez and Griswold 2013:
Gonzalez, V.H. and T.L. Griswold. 2013. Wool carder bees of the genus Anthidium in the Western Hemisphere (Hymenoptera: Megachilidae): diversity, host plant associations, phylogeny, and biogeography. Zoological Journal 168: 221ndash;425.).

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 2013Gonzalez and Griswold 2013:
Gonzalez, V.H. and T.L. Griswold. 2013. Wool carder bees of the genus Anthidium in the Western Hemisphere (Hymenoptera: Megachilidae): diversity, host plant associations, phylogeny, and biogeography. Zoological Journal 168: 221ndash;425.). 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 2013Gonzalez and Griswold 2013:
Gonzalez, V.H. and T.L. Griswold. 2013. Wool carder bees of the genus Anthidium in the Western Hemisphere (Hymenoptera: Megachilidae): diversity, host plant associations, phylogeny, and biogeography. Zoological Journal 168: 221ndash;425.).

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

References

Gonzalez, V.H. and T.L. Griswold. 2013. Wool carder bees of the genus Anthidium in the Western Hemisphere (Hymenoptera: Megachilidae): diversity, host plant associations, phylogeny, and biogeography. Zoological Journal of the Linnean Society 168: 221-425.