Anthidium porterae

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Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Anthidiini
Genus: Anthidium Fabricius, 1804
Subgenus: A. (Anthidium) Fabricius, 1804
Species: Anthidium porterae Cockerell, 1900
Common name: none

Overview

Anthidium (Anthidium) porterae are black, with some light ferruginous coloration on the legs and abdomen, and yellow maculations (Gonzalez and Griswold 2013). Females have white pubescence except for yellow pubescence on the vertex, scutum, axilla, scutellum, inner tarsi, and sometimes S6. The clypeus and distal half of the supraclypeal area are covered in apically hooked hairs. Females have a body length of 9.2–12.3 mm, and males vary in length from 11.5–13.1 mm (Gonzalez and Griswold 2013).

Diagnostic characteristics

(modified from Gonzalez and Griswold 2013)

• Female labrum lacks basal protuberances and has two large preapical projections that curve upwards.
• Female mandible has 6–7 teeth.
• Female propodeal triangle is dull and finely imbricate to lineolate.
• Female hind tibia with anterior carina present.
• Female T1–T5 discal areas are strongly elevated with dull or weakly shiny, finely imbricate areas between punctures.
• Female T1–T5 depressed marginal zones are coarsely punctate.
• Female T1–T5 apical impunctate zones are narrow, and the margins are doubly carinate.
• Female T6 depressed apical rim laterally projected into ventral lobes.
• Female T6 is elevated along the midline with a small lateral angle and minutely crenulate preapical carina.
• Male S4 median apical brush is broad and dense, with reddish-brown hairs on the median one-third of the concave apical margin.
• Male S6 lacks lateral projections and has a broadly rounded median lobe.
• Male S6 with a median preapical carina projected as a long spine.
• Male S7 is apically pointed.
• Male S8 apical process is long, broad, and weakly bifid.
• Male T6 lateral spine is weakly curved and about as long as T7 median spine.
• Male T7 lateral lobe is subquadrate, and about 1.5 times broader than the distance between the inner margin and median spine.

May be confused with

Anthidium porterae can be differentiated from all Anthidium in the New World by the presence of the depressed apical rim that projects into a distinct ventral lateral lobe on female T6, and median preapical carina that projects as a long spine on male S6 (Gonzalez and Griswold 2013). Anthidium porterae may be confused with A. cochimi due to the clypeus with apically hooked hairs, tomentum on the outer hind basitarsi, and depressed apical rim that projects into a small ventral lobe on T6 (Gonzalez and Griswold 2013). Female A. porterae can be differentiated from A. cochimi by the presence of large, distinct preapical projections on the labrum and the elevated midline of T6 (Gonzalez and Griswold 2013).

Phenology

Anthidium porterae adults have been recorded in flight from April to early November, with peak activity occurring from late June to the first half of September (Gonzalez and Griswold 2013).

Host associations

Anthidium porterae is a generalist that has been observed visiting a variety of species within Apocynaceae, Asteraceae, Boraginaceae, Fabaceae, Loasaceae, and Plantaginaceae (Gonzalez and Griswold 2013).

Nesting behavior

Anthidium porterae has been observed nesting in shallow abandoned burrows in the ground (Custer and Hicks 1927). The nest contains a single cell that is comprised of plant trichomes from Artemisia campestris (Asteraceae) and Cryptantha sp. (Boraginaceae) (Custer and Hicks 1927). Nest plugs are constructed with pebbles. Males defend floral resources preferred by females (Villalobos and Shelly 1991).

Distribution

Anthidium porterae occur in the U.S. in Arizona, South Dakota, Nebraska, Oklahoma, Texas, Utah, and Wyoming. In Mexico, they are found in Baja California Sur, San Luis Potosi, and Chihuahuan to Aguascalientes. They are restricted to grasslands, Edwards Plateau savanna, Colorado Rockies, Arizona mountain forests, Colorado Plateau shrublands, Chihuahuan desert, Sierra Madre Occidental pine-oak forests, and central Matorral ecosystems (Gonzalez and Griswold 2013).

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