J. HYM. RES. Vol. 9(1), 2000, pp. 182-208 A Revision of the Panurgine Bee Genus Arhysosage (Hymenoptera: Andrenidae) Michael S. Engel Division of Invertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024-5192, USA Abstract. — The South American bee genus Arhysosage Brethes (Panurginae: Calliopsini) is re-vised. In addition to the previously recognized Arhysosage flava Moure, A. cactorum Moure, A. ochracea (Friese), and A. bifasciata (Friese) (new combination), two new species are described: A. atrolnnata Engel and A. zamicra Engel. Arhysosage germana Moure is newly synonymized with A. ochracea and A. melanothricha Moure is synonymized with A. cactorum, while A. bifasciata is resurrected from synonymy under A. ochracea with Camptopoeum opuntiarum Torgensen as a junior subjective synonym (new synonymies). The genus is newly diagnosed and a key to the currently recognized species is presented. The name appearing in the literature as A. xanihina is a nomen nudum. The phylogenetic position of the genus among other calliopsine bees is briefly summarized as are relationships among the species. A cladistic analysis of Arhysosage produces a single tree with the following hierarchy: A. cactorum (A. flava, A. zamicra (A. ochracea (A. atrolunata, A. bifas-ciata))). Biological information on Arhysosage is summarized. The genus is presently known from Argentina, southern Brazil, Bolivia, and Paraguay and is apparently a specialist on Cactaceae (presently recorded from Echinocactus, Echinopsis, Gymnocalycium, Notocactus, Opuntia, and Tricho-cereus). Bees of the genus Arliysosage Brethes (1922) are among the most distinctive of the South American panurgines, being characterized by the fairly robust size of most individuals, large heads of males, and mostly yellow body coloration (Fig. 1). Individuals can be readily captured at flowers of various cactus genera (e.g., Gymnocalycium, Notocactus, Opuntia, &c.) upon which they are presumably oligolec-tic (Schlindwein 1992, Schlindwein and Wittmann 1995). Outside of their affinity for cactus flowers, however, the biology of Arhysosage species has not been the focus of any published study, although Schlind-wein and Wittmann (1995) give a few de-tails of mating behavior in Arhysosage. Their observations indicate that mating is initiated at cactus flowers. Males search flowers for females, sometimes staying motionless in inflorescences for up to sev-en minutes. Once a female appears, the male grabs her waist with his long man-dibles and initiates copulation. The couple frequently continues mating during flight and may visit several flowers throughout the encounter, with the female continuing to forage the whole time. Such mating be-havior is reminiscent in some respects to that described for Perdita (Macrotera) tex-ana (Cresson 1878). Like Arhysosage, this group is oligolectic on Cactaceae (Snelling and Danforth 1992, Neff and Danforth 1992) and also demonstrates a dramatic head-size polymorphism in males that, among other uses, allows males to grasp females during copulation (Danforth and Neff 1992). Future field work on Arhyso-sage species should explore possible etho-logical-morphological associations in males as has been done for Perdita. The genus was established by Brethes (1922) for an enigmatic bee species in northern Argentina, but its systematic po-
BioStor
