Title: Studies on the Tropisternus mexicanus Complex (Coleoptera: Hydrophilidae) I. The Biology of the Races and their Genetic Crosses
Abstract: A comparison of the various stages in the life cycle of three members of the Tropisternus mexicanus (Castelnau) complex revealed no significant differences in the durations of the instars in the different races. Egg production rates and overall survival rates were also very similar. Genetic crosses between the three races proved possible, and the evidence from these crosses indicates that the three should retain their current taxonomic position as subspecies of T. mexicanus. The three races appear to be closely related physiologically, although a beginning of divergence is suggested between T. m. mexicanus and T. m. viridis Young and Spangler.