Colony foundation, nest architecture and demography of a basal fungus-growing ant, Mycocepurus smithii (Hymenoptera, Formicidae)

The genus Mycocepurus is a phylogenetically basal attine ant, so studies of its biology may provide insight into the evolution of behaviours associated with fungus-growing that characterize the tribe Attini. Mycocepurus smithii from Puerto Rico produces sexual females from July to September, but no males were observed in 2 years of observations, confirming previous observations elsewhere. Colonies were founded between July and August and most nests were haplometrotic (85% of 74 nests). After excavating a tunnel and small chamber, a foundress queen inserted her fore wings into the ceiling and used the wing surfaces as a platform on which the incipient fungal garden was grown. Foundresses foraged for substrate to grow the fungus garden. Growth of incipient colonies was slow: the first workers emerged 2–5 months after colony founding and, after 8 months, colonies contained on average only a single worker.