In this study, the first records of lesions in osteoderms of Holmesina, a group of fossil cingulates related to armadillos, possibly caused by the action of penetrating fleas (Siphonaptera) are described. Three individuals of Holmesina cryptae (Pampatheriidae) were collected from Quaternary sediments in Lapinha Cave (Iramaia, Bahia state, Brazil). Their osteoderms were analyzed by stereomicroscope and scanning electron microscopy and alterations on their surfaces were recognized. We found 63 marks distributed in 23 of 1300 analyzed osteoderms (approximately 1.8% of the total of osteoderms), characterized by vertical cavities with well-delimited circular borders similar to those lesions made by Tungidae fleas in extant mammals. These records indicate that there was an interaction between penetrating fleas and pampatheres during the Quaternary in Brazilian Intertropical Region, and contribute to the understanding of the evolution of these ectoparasites and the relationship with their hosts.
