Natural history and daily rhythm activity of the myrmecophytic ant, Pseudomyrmex concolor Smith (Hymenoptera, Formicidae)

Many neotropical ants form mutualistic associations with myrmecophytes, receiving shelter and/or food in exchange for protection. However, our knowledge about their natural history is still unclear. Here, we investigate the natural history of ant Pseudomyrmex concolor that nests inside the foliar rachis of Tachigali myrmecophila (Fabaceae). We describe the nest architecture, colony structure and rhythm activity of P. concolor in the Brazilian Amazon. We found P. concolor nests exclusively in T. myrmecophila. Its colony is established by claustral foundation with an independent queen, which remains the colony's only egg-laying. The nest of P. concolor is a hollow tubular construction of the swollen leaf petiole that constitutes the domatia of T. myrmecophila. The colony structure of P. concolor (eggs, larvae, pupae and adults) depends on plant traits, such as plant height, number of leaves and internal space of the domatia. Tachigali myrmecophila does not provide food for P. concolor, and the mealybugs are their only food source. Pseudomyrmex concolor has a bimodal cycle of activity, patrolling its host plant for 24 h a day and throughout the year, mainly during the Amazonian rainy season nights. Humidity and temperature are environmental factors that can explain much of the variation in the rhythm of this ant species daily activity, but not the change between the seasons. Our findings improve the knowledge of ant-plant mutualisms and eco-evolutionary studies on tropical forests.

Automated summary

In this study, the natural history of the ant Pseudomyrmex concolor nesting inside Tachigali myrmecophila in the Brazilian Amazon was investigated. The nest architecture, colony structure, and activity rhythm of P. concolor were described. It was found that the colony structure of P. concolor depends on plant traits and that mealybugs are their only food source. The ant has a bimodal cycle of activity and is mainly active during the rainy season nights in the Amazon.