Black bees in the desert: Description of a new species of wool carder bee (Hymenoptera, Megachilidae, Anthidium) from the northern Sahara with colouration atypical for xeric environments

Bees inhabiting xeric environments often exhibit, like many other insects, brown, beige, and sandy colours, aligning with the hues of the desert landscape. In this study, we study two bee species belonging to the tribe Anthidiini that defy this general colour pattern. These species feature an almost entirely black integument, contrasting with the typical rich yellow or beige colour pattern found in most members of the genus Anthidium Fabricius, 1804. The new species, A. nigrum Kasparek, sp. nov., was found in the deserts of the northern Sahara, where also another dark congener lives, the little-known Anthidium pullatum Morice, 1916, which is re-described here based on the rediscovery of the type material which has been thought lost. We hypothesise that this colouration phenomenon may be explained by an adaptation to the strong day-and-night temperature differences in the desert environment. The black colouration enables bees to harness solar energy early in the day, capitalizing on enhanced heat retention due to the lower reflectance of their integument. It is hypothesized that this allows bees to optimize their activity pattern during the brief period before temperatures rise to levels posing a high risk of overheating.