A comparative analysis of the venom alkaloids of 13 species of ants in the genus Monomorium collected in Africa was undertaken. Ants were collected in Kenya and South Africa. Most species produced 2,5-dialkylpyrrolidines and some of their analogous 1-pyrrolines. No alkaloids were detected in two species, M. robustior and M. macrops. Additionally, a novel 2-alkyl-1-pyrroline, whose structure was established by synthesis, was detected in M. notulum. This compound and others like it may serve as biosynthetic precursors for the formation of the 2,5-dialkylpyrrolidines found in many Myrmicine ant species.