Plesianthidium

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Anthidiini
Genus: Plesianthidium Cameron, 1905
Subgenera: Carinanthidium, Plesianthidium, Spinanthidiellum, Spinanthidium
Common name: none

Overview

Plesianthidium typically have robust bodies which lack any pale markings, except for pale markings and hairs on their face. They range in body length from 7–16 mm, with the largest being P. fulvopilosum, which ranges in body length from 15–16 mm (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.).

Diversity

Plesianthidium contains 12 species within four subgenera in southern Africa (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.); none are known to occur in the U.S. or Canada.

Diagnostic characteristics

(modified from Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.)

• Arolia present.
• Front and middle tibiatibia:
  the segment of the leg, between the femur and the tarsus
  , particularly in females, are broad with convexconvex:
  curved outward
  , apicalapical:
  near or at the apex or end of any structure
  spines.
• Juxtantennal carinacarina:
  a clearly defined ridge or keel, not necessarily high or acute; usually appears on bees as simply a raised line
  absent.
• Omaular carinae absent.
• Subantennal sutures straight.
• Scutellum scutellum:
  shield shaped plate behind scutum
  rounded and barely overhanging the metanotummetanotum:
  the posterior dorsal segment of the thorax, behind the scutellum
  .
• Male with marginal comb on 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
  .
• 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
  is trifid or trilobed.
• 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
  is three-toothed, or has a reduced middle tooth between two long, separated teeth.
• Males have a simple, hairy gonostylusgonostylus:
  the apical-most appendage of the male genitalia, which is usually quite hairy
  .

May be confused with

Plesianthidium, especially species within subgenus Carinanthidium, may be confused with Aspidosmia due to a lack of yellow or pale markings on the abdomen. Plesianthidium males can be distinguished by the presence of a marginal comb on 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
the tridentatetridentate:
having three teeth
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
. Aspidosmia males lack marginal combs on all sternasterna:
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
and have a bilobed or bidentatebidentate:
having two teeth
T7. Females can be readily distinguished because Plesianthidium lacks the scopa-like hairs on the hind tibiatibia:
the segment of the leg, between the femur and the tarsus
present in Aspidosmia.

Known invasives

There are no known invasives.

Host associations

Plesianthidium have been observed visiting flowers within the families Fabaceae, Malvaceae, and Lamiaceae (Gess and Gess 2007Gess and Gess 2007:
Gess, S.K. and F.W. Gess. 2007. Notes on nesting and flower visiting of some anthidiine bees (Hymenoptera: Megachilidae: Megachilinae: Anthidiine) in southern Africa. Journal of Hymenoptera Research 16: 30ndash;50.).

Nesting behavior

Plesianthidium build nests out of resin (Gess and Gess 2007Gess and Gess 2007:
Gess, S.K. and F.W. Gess. 2007. Notes on nesting and flower visiting of some anthidiine bees (Hymenoptera: Megachilidae: Megachilinae: Anthidiine) in southern Africa. Journal of Hymenoptera Research 16: 30ndash;50.). Plesianthidium volkmanni has been observed nesting in electrical boxes 1.25 m above the ground (Gess and Gess 2007Gess and Gess 2007:
Gess, S.K. and F.W. Gess. 2007. Notes on nesting and flower visiting of some anthidiine bees (Hymenoptera: Megachilidae: Megachilinae: Anthidiine) in southern Africa. Journal of Hymenoptera Research 16: 30ndash;50.). Nests include up to seven, separate pot-like cells made of ochre/yellow-colored resin. The females will first create a small saucer to act as a foundation for the nest. The saucer is made out of a different material than the nest (Gess and Gess 2007Gess and Gess 2007:
Gess, S.K. and F.W. Gess. 2007. Notes on nesting and flower visiting of some anthidiine bees (Hymenoptera: Megachilidae: Megachilinae: Anthidiine) in southern Africa. Journal of Hymenoptera Research 16: 30ndash;50.). Cells are then built horizontally from the base. The nest is plugged using a tapered and narrow spout, which is likely used to ventilate the cells (Gess and Gess 2007Gess and Gess 2007:
Gess, S.K. and F.W. Gess. 2007. Notes on nesting and flower visiting of some anthidiine bees (Hymenoptera: Megachilidae: Megachilinae: Anthidiine) in southern Africa. Journal of Hymenoptera Research 16: 30ndash;50.).

Distribution

Plesianthidium are distributed in southern Africa, specifically Namibia and South Africa. Almost all species of Plesianthidium are found in Cape Province, South Africa (Michener 2007Michener 2007:
Michener, C.D. 2007. The Bees of the World (2nd ed.). Johns Hopkins University Press, Baltimore and London, 953 pp.).

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References

Gess, S.K. and F.W. Gess. 2007. Notes on nesting and flower visiting of some anthidiine bees (Hymenoptera: Megachilidae: Megachilinae: Anthidiini) in Southern Africa. Journal of Hymenoptera Research 16:30-50.
 
Michener, C.D. 2007. The Bees of the World. 2nd ed. Johns Hopkins University Press, Baltimore and London, 953 pp.