New species of the cleptoparasitic bee genus Stelis (Hymenoptera: Megachilidae, Anthidiini) from the Nearctic Region.

Descriptions and diagnoses of ten new Nearctic species of Stelis subgenus Stelis are presented: S. alta, S. anasazi, S. anthocopae, S. broemelingi, S. imperialis, S. joanae, S. lamelliterga, S. occidentalis, S. paiute, and S. shoshone. Six of these species have been reared from trapnests. Host associations, all within the tribe Osmiini (Megachilidae), are provided.

A new bee species that excavates sandstone nests.

Humanity has long been fascinated by animals with apparently unfavorable lifestyles [1]. Nesting habits are especially important because they can limit where organisms live, thereby driving population, community, and even ecosystem dynamics [2]. The question arises, then, why bees nest in active termite mounds [3] or on the rim of degassing volcanoes, seemingly preferring such hardship [4]. Here, we present a new bee species that excavates sandstone nests, Anthophora (Anthophoroides) pueblo Orr (described in Supplemental Information, published with this article online), despite the challenges already inherent to desert life. Ultimately, the benefits of nesting in sandstone appear to outweigh the associated costs in this system.