The New Mexico Rare Arthropod Resource

Little habitat and ecology information is known for this species. Based on where it has been recorded, it is likely found in arid shrublands or grasslands in lowland areas of the Madrean Sky Island and Chihuahuan Desert ecoregions. Bees in this genus are often specialists on plants in various families (Carril and Wilson 2023). This species has been documented only on species of fiddleleaf (Nama spp.), including Nama lobbii and N. hispidum, in the Boraginaceae family (Ascher and Pickering 2024). Hesperapis species nest in the ground, often in sparse aggregations (Carril and Wilson 2023).

This species occurs in the southwestern United States, where it has been recorded at several localities across southeastern Arizona (Chesshire et al. 2023) and one locality in central New Mexico, at the Sevilleta National Wildlife Refuge (Wright et al. 2023). It is suggested the species is also known from Texas (Ascher and Pickering 2024), though no digitized records are available to confirm this.

There are no conservation measures in place for this species. It is known to occur in at least one protected are, the Sevilleta National Wildlife Refuge (Wright et al. 2023), though this will not protect against the main threat of increased drought due to climate change. Research is needed to better understand the distribution, population size and trend, habitats and ecology, and threats to this species.

The threats to this species are not well understood. Climate warming may have impacts across the range of this species, particularly due to increasing drought conditions. The southwestern U.S. saw its driest 22-year period from 2000 to 2021, since at least 800 CE (the time period used in previous climatic reconstructions) (Williams et al. 2022). Droughts are projected to become more prolonged, severe, and common in the region under future climate change scenarios (USGCRP 2018). Drought may negatively impact bee species by reducing floral resource availability (Phillips et al. 2017). Bees that are oligolectic, like this one, are generally at higher risk of extinction due to reduced host plant availability, especially under climate change scenarios (Roberts et al. 2011) and reduced effective population sizes (Packer et al. 2005).

The population size and trend are not known for this species. In the last 20 years, the species has only been recorded at the Sevilleta National Wildlife Refuge (Wright et al. 2023). Even then, only one specimen was found in 2012, despite surveys from 2002 through 2018. There are no recent records from Arizona. While sampling effort is unknown, there are regular bee surveys near Portal, Arizona at least, where this species has been recorded in the past.

• Roberts, S.P.M., Potts, S.G., Biesmeijer, K., Kuhlmann, M., Kunin, B. and Ohlemüller, R.. 2011. Assessing continental-scale risks for generalist and specialist pollinating bee species under climate change. BioRisk 6.
• Ascher, J.S. and Pickering, J.. 2024. Discover Life bee species guide and world checklist (Hymenoptera): Hesperapis trochanterata Snelling, 1987. https://www.discoverlife.org/mp/20q?search=Hesperapis+trochanterata&flags=subgenus:
• Wright, K.W., Kazenel, M.R., Bettinelli, J., Griswold, T.L., McLellan, J., Whitney, K.D. and Rudgers, J.A.. 2023. Bee species abundance and composition in three ecosystem types at the Sevilleta National Wildlife Refuge, New Mexico, USA ver 7. Environmental Data Initiative. Environmental Data Initiative. https://doi.org/10.6073/pasta/5a007cc78cf32244cb8a812f5be2ef60
• Rozen, J.G.. 1987. Nesting biology and immature stages of a new species in the bee genus Hesperapis (Hymenoptera: Apoidea: Mellitidae: Dasypodinae). American Museum Novitates 2887.
• Phillips, B.B., Shaw, R.F., Holland, M.J., Fry, E.L., Bardgett, R.D., Bullock, J.M. and Osborne, J.L.. 2017. Drought reduces floral resources for pollinators. Global Change Biology 24: (3226-3235).
• Chesshire, P.R., Fischer, E.E., Dowdy, N.J., Griswold, T.L., Hughes, A.C., Orr, M.C, Ascher, J.S. Guzman, L.M, Hung, K-L.J., Cobb, N.S. and McCabe, L.M.. 2023. Completeness analysis for over 3000 United States bee species identifies persistent data gap. Ecography e06584: (1-13).
• Packer, L., Zayed, A., Grixti, J.C., Ruz, L., Owen, R.E., Vivallo, F. and Toro, H.. 2005. Conservation genetics of potentially endangered mutualisms: reduced levels of genetic variation in specialist versus generalist bees. Conservation Biology 19: (195-202).
• Wilson, J.S. and Carril, O.M. 2016. The Bees in Your Backyard: A Guide to North America's Bees. Princeton University Press, Princeton, NJ .
• Williams, A.P., Cook, B.I. and Smerdon, J.E. . 2022. Rapid intensification of the emerging southwestern North American megadrought in 2020–2021. Nature Climate Change 12: (232-234).
• USGCRP. 2018. Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II. U.S. Global Change Research Program , Washington, DC, USA : (1515).
• ITIS. 2024. Integrated Taxonomic Information System (ITIS). 2024. https://www.itis.gov/