AbstractA key, synonymy, descriptions and distributions are given for twelve species ofCeratina (Euceratina), including three new species, C.maghrebensis, C.neocallosa, C.saundersi; two species ofCeratina (Ceratina, s.s.); and two species ofPithitis. A neotype is designated forC.callosaand lectotypes forC.callosa algeriensis, C.chalybea, C.cyanea imitatrix, C.decolorans, C.laevifrons moricei, C.mocsaryi and C.nigrolabiata. Ecology of bees in overwintering nests in Tunisia is discussed. Evidence is given for congeneric interference competition for nesting substrates and resource partitioning.C.dallatorreanais shown to reproduces probably entirely by thelytoky and thus is unique among Apoidea.