Nesting and foraging behavior were studied in Cephalurgus anomalus and Perditomorpha brunerii, two oligolectic bee species on Malvaceae flowers, in the University of São Paulo campus, Ribeirão Preto, Brazil. Bees were monitored on flowers of Sida, Malvastrum, Gaya and Wissadula. Perditomorpha brunerii females collect pollen with the forelegs and abdomen to transport it in short-branched hairs on the hind tibia and metasomal sterna; males patrol flowers and spend the night in closed flowers of Sida cerradoensis and Sida sp. C. anumalus females lean the dorsal region of the body agains the petals and collect pollen with the forelegs, accumulating the grains on the mesepisterna before placing them into sparse unbrached hairs on tha anterior outer side of the hind tibiae; males patrol and wait for females in flowers, here the copulate throughout the foraging season. Both speces nest in the soil among the host plants. P. brunerii bees buidl solitary nests; whereas in C. anumalus one or more foraging females are associated with an individual nest. The nests, in both species, consist of a descent straight main tunnel and cells arranged singly and horizontally at the end of the branches, which are filled with soil. The efficient foraging behavior, location of the nestes among the host plants and scopal setae that allow the transport of large pollen grains in large amounts indicate an inimate association between these two bee species and Malvaeae flowers.

Keywords: Behavior, foraging, Malvaceae, nests, oligolectic bees, Perditomorpha, Cephalurgus