U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Document Type


Date of this Version



Zoological Journal of the Linnean Society, 2013, 168, 221–425.


Bees are among the most important pollinators of flowering plants in most ecosystems. Recent concerns about population decline worldwide have highlighted the urgent societal need for species-level systematic work that facilitates assessments of the status of pollinators and pollination services. This is a comprehensive, broadly comparative study on the diversity, biology, biogeography, and evolution of Anthidium Fabricius, 1804, one of the most diverse megachilid genera, containing more than 160 species worldwide. Herein, the Western Hemisphere species are revised. All 92 recognized species, including the two adventive species Anthidium oblongatum (Illiger, 1806) and Anthidium manicatum (Linnaeus, 1758), are described and illustrated. A neotype for Anthidium emarginatum (Say, 1824) and lectotypes for 16 names are designated; five names are relegated to synonymy, three names are revalidated, previously unknown males of three species are described, and 21 new species are proposed. Identification keys as well as information on the distribution, seasonality, nesting biology, and host plants are provided. The relationships of the Anthidium subgenera and all Western Hemisphere species are explored using a cladistic analysis based on adult external morphological characters. The subgenus Callanthidium Cockerell, 1925, renders Anthidium s.s. paraphylectic in the analysis, and is here synonymized. The resulting phylogenetic hypothesis is used to examine possible biogeographical patterns, origins of the Western Hemisphere fauna, and the evolution of morphological traits associated with foraging for pollen from nototribic flowers and exudates from glandular trichomes. To facilitate the transfer of knowledge to non-specialists, some digital outputs and web-based products, including a geo-referenced specimen database consisting of more than 20 000 records, species pages, and interactive digital keys, were also developed during this study.