Collections of Drosophila made at altitudes of 200–3300 m at Bogotá and elsewhere in Colombia have yielded D. mesophragmatica Duda, D. viracochi Brncic and Koref, D. gasici Brncic, and a new species, D. brncici, which seems most nearly allied to D. gasici. The other 4 species of the mesophragmatica group are known at present only from areas outside Colombia. The results of crosses between isofemale lines of Bogotá mesophragmatica and stocks of D. pavani Brncic and D. gaucha Jaeger and Salzano indicate that the Bogota strain differs genetically from the mesophragmatica of Bolivia and Peru.