This book deals with two lineages of solitary bees that are distributed throughout the Neotropical Region, collecting oil from plants with oil-bearing flowers, producing their reproduction.

New species for science belonging to the two groups studied are described here: the subgenera Centris (Aphemisia) and C. (Schisthemisia). Additionally, diagnoses of the species already described, identification keys, a complete list of floral hosts, distribution maps and an updated catalogue of all the species studied are also presented.