Delayed maturation of the exoskeleton and muscle fibres in the ant Platythyrea punctata

In many species of eusocial Hymenoptera, workers exhibit a division of labour based on age, wherein young workers remain protected within the nest before transitioning to foraging activities. These changes in tasks and in external stress exposure are accompanied by physiological and anatomical modifications. Although pigmentation changes in the exoskeleton are well documented in ants, limited information is available on muscle morphology and developmental changes in the adult cuticle. Here, we investigated the alterations in the exoskeleton and thoracic muscles across different age groups of the clonal ant Platythyrea punctata, in which reproduction is monopolized by one or a few dominant workers. Our findings revealed a significant thickening of the cuticle and muscle fibres in young workers during the intranidal period, reaching a final stage in forager individuals. We further tested the influence of reproductive status on body development and found variations only in muscle fibres between reproductive and nonreproductive individuals. This suggests that dominant individuals allocate resources in egg-laying by minimizing other metabolic costs. These findings shed light on how eusociality profoundly alters selection pressures and results in temporal shifts in individual development. This strategy probably provides advantages to colonies by minimizing nutritional waste and optimizing resource allocation.