PROC. BIOL. SOC. WASH. 93(1), 1980, pp. 229-283 EIGHTEEN NEW SPECIES OF BRUCHIDAE, PRINCIPALLY FROM COSTA RICA, WITH HOST RECORDS AND DISTRIBUTIONAL NOTES (INSECTA: COLEOPTERA) John M. Kingsolver Abstract. — Diagnostic descriptions, illustrations of salient characters, geographic distribution, and host plants are given for the following new species: Amblycerus epsilon, A. imperfectus, A. multiflocciilus, A. ptero-carpae, A. spondiae, A. vegai, Zabrotes chavesi, Merobruchus santarosae, M. boucheri, M. hastatus, M. paquetae, M. sonorensis, M. terani, Acan-thoscelides hectori, A. Johns oni, A. megacornis, A. petalopygus, and A. triumfettae. Blackwelder's checklist (1946) of neotropical Coleoptera included only 9 species of Bruchidae from Costa Rica. Essentially no biological data were available for any of the Central American species at that time. In the last 15 years, however, largely through the intensive efforts of D. H. Janzen, University of Pennsylvania, Philadelphia, and his students, a prodigious amount of specimens and data has accumulated on the bruchids of Costa Rica, both in numbers of species represented, and in knowledge of life histories and host plant associations. The number of species now known from that country is 135, more than one-half of them undescribed when collected. Approximately 75% of these species have been reared from field collections of seeds, making this fauna one of the best known in the world for bruchids. Janzen's comprehensive studies on seed-seed predator inter-action systems resulting from his collecting and rearing activities has stim-ulated a number of taxonomic papers on bruchids from Costa Rica including this paper. The purpose of this paper is to describe for the first time 18 species of Bruchidae involved in Janzen's ecological studies. Keys to species described in this paper are not provided because the genera represented are large, and all are being taxonomically revised at this time. Species herein included comprise only small parts of their respective genera. Primary type-specimens are deposited in the United States National Mu-seum of Natural History, Washington, D.C. (USNM). Paratypes of all species are deposited in USNM, in the C. D. Johnson Collection, Flagstaff, AZ, and in the Canadian National Collections, Ottawa, Ontario (CNCI).