The New Mexico Rare Arthropod Resource

Macrotera magniceps is often collected in large dune formations, suggesting it prefers mostly sandy soils (Danforth 1996). The nesting habits of this particular species are unknown, though Macrotera species typically nest in the ground, sometimes communally. They are usually oligolectic, often specializing on plants in the mallow or cactus families (Malvaceae and Cactaceae respectively) (Carril and Wilson 2023). This species is usually collected on globe mallow species (Sphaeralcea spp.), which it appears to specialize. In particular, it is associated with S. incana, a distinct species, which grows up to two meters in height in very dry, sandy localities (Danforth 1996).

This goblin bee is known from a few scattered occurrences in the southwestern United States and northern Mexico. It was described from a male collected near Deming, New Mexico (Timberlake 1960), and has since been recorded from Los Lunas, Albuquerque, and the Sevilleta National Wildlife Refuge (Gordon 2022, Armijo-Prewitt 2019, Chesshire et al. 2023). There are also records from the American Museum of Natural History from unknown localities within Arizona and Texas, though these records are not digitized so further information, such as collection date, is not available (Ascher and Pickering 2024). It has also been recorded in Ciudad Juarez and the Samalayuca Dunes in Chihuahua, Mexico (Chesshire et al. 2023). The is an outlying record from Chiapas, in southern Mexico, collected in 1991 (Chesshire et al. 2023).  Records for Arizona, Texas, and Chiapas were not included in the range stated by Danforth (1996), so they may not be accurate.

There are no conservation measures in place for this species. It is known to occur in at least one protected area, the Sevilleta National Wildlife Refuge, though it is not removed from the main threat of severe drought in this refuge. Research is needed to better understand the current distribution, population size and trend, habitats and ecology, and threats.

The threats to this species are not well understood, though drought is likely the main threat. 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). In addition, declines observed in Macrotera species at one site the Chihuahuan Desert have been attributed to small body size of these bees, and associated sensitivity to heat and desiccation (Kazenel et al. 2024).

The population size and trend are not well understood for this species. However, based on 16 years of abundance data from the Sevilleta National Wildlife Refuge and experimentally determined heat and desiccation tolerances, climate sensitivity models predict this species is likely to decline in the coming years (Kazenel et al. 2024). This species has only been recorded recently in New Mexico. Surveys are needed to ensure the species remains extant across the range.

• 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: (13-Jan).
• Danforth, B.N.. 1996. Phylogenetic Analysis and Taxonomic Revision of the Perdita Subgenera Macrotera, Macroteropsis, Macroterella and Cockerellula (Hymenoptera: Andrenidae) . University of Kansas Science Bulletin 55: (635-692).
• Timberlake P.H.. 1960. A revisional study of the bees of the genus Perdita F. Smith, with special reference to the fauna of the Pacific Coast (Hymenoptera, Apoidea) Part IV. University of California Publications in Entomology 17: (1-156).
• Ascher, J.S. and Pickering, J.. 2024. Discover Life bee species guide and world checklist (Hymenoptera): Macrotera magniceps (Timberlake, 1960). 2024. https://www.discoverlife.org/mp/20q?search=Macrotera+magniceps&flags=subgenus:
• Gordon, E.. 2022. iNaturalist observation:. 2024. https://www.inaturalist.org/observations/130428520
• Armijo-Prewitt, T.. 2019. iNaturalist observation. 2024. https://www.inaturalist.org/observations/27107432
• Kazenel, M.R., Wright, K.W., Griswold, T., Whitney, K.D. and Rudgers, J.A.. 2024. Heat desiccation tolerances predict bee abundance under climate change. Nature 628: (342-362).
• 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).
• 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/
• Carril, O.M. and Wilson, J.S.. 2023. Common Bees of Western North America. 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).