Crystalline deposits reveal caste identity of late embryos and larvae of the ant Cardiocondyla obscurior

Social insects are interesting models for the study of anticipatory developmental plasticity because of the striking differentiation into reproductive queens and functionally sterile workers. A few ant genera, including Cardiocondyla, represent the pinnacle of social evolution in the Hymenoptera, where workers have completely lost their reproductive organs, minimizing reproductive conflicts between queens and workers. Here we show that late embryos and larvae of queens of the ant C. obscurior can be identified by the appearance of urate deposits around the forming ovaries. The discovery of caste-specific urate patterns in C. obscurior and three additional Cardiocondyla species will facilitate future studies of developmental plasticity in ants.