Spirochete-like cells in a Dominican amber Ambylomma tick (Arachnida: Ixodidae)

Amber preserves microscopic, soft-bodies organisms and is a good medium in which to trace the evolution of pathogen–vector associations. Spirochetes-like cells (Spirochaetales: Spirochaetaceae) in the hemocoel and lumen of the alimentary tract of a larva tick (Amblyomma sp. Arachnida: Ixodidae) in Dominican amber are described in the collective fossil genus and species, Palaeoborrelia dominicanan. gen., n. sp. The size and shape of the fossil spirochetes closely resemble those of present-day Borrelia species. This discovery represents the first record of spirochete-like cells associated with fossil ticks.