Haetosmia is a species-poor genus of osmiine bees (Megachilidae) containing six species, which inhabit deserts and semideserts from the Canary Islands to Central Asia. Formerly considered to be restricted to the southern Palaearctic region, the genus is shown here to occur also in the northern Afrotropical region. The females of all six Haetosmia species collect pollen from the narrow-tubed flowers of Heliotropium (Boraginaceae) with the aid of specialized pollen-harvesting bristles on the proboscis. Current knowledge suggests that Haetosmia species are restricted to sandy habitats, excavate their nests in the ground and use chewed leaves to construct their urn-shaped brood cells, which are placed side by side in an enlarged chamber at the end of the nesting burrow. The taxonomic revision of Haetosmia revealed the existence of two undescribed species, H. ethiopiensis spec. nov. from eastern Africa and H. pakistaniensis spec. nov. from Pakistan. Due to clear morphological gaps and overlapping distribution area with the nominotypical subspecies, H. brachyura altera (Peters 1974) is elevated to species rank. Keys for the identification of the six Haetosmia species are provided.
Keywords: Hymenoptera, Apiformes, Heliotropium, host-plant choice, Hymenoptera, nesting behaviour, oligolectic, pyrrolizidine alkaloids.