Fossilized Mammalian Erythrocytes Associated With a Tick Reveal Ancient Piroplasms.

Ticks transmit a variety of pathogenic organisms to vertebrates, especially mammals. The fossil record of such associations is extremely rare. An engorged nymphal tick of the genus Ambylomma in Dominican amber was surrounded by erythrocytes from its mammalian host. Some of the exposed erythrocytes contained developmental stages of a hemoprotozoan resembling members of the Order Piroplasmida. The fossil piroplasm is described, its stages compared with those of extant piroplasms, and reasons provided why the mammalian host could have been a primate. The parasites were also found in the gut epithelial cells and body cavity of the fossil tick. Aside from providing the first fossil mammalian red blood cells and the first fossil intraerythrocytic hemoparasites, the present discovery shows that tick-piroplasm associations were already well established in the Tertiary. This discovery provides a timescale that can be used in future studies on the evolution of the Piroplasmida.
(© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com Version of Record, first published online March 20, 2017 with fixed content and layout in compliance with Art. 8.1.3.2 ICZN.)