First Mesozoic Record of a Parasitiform Mite: a Larval Argasid Tick in Cretaceous Amber (Acari: Ixodida: Argasidae)

Abstract

A larval argasid tick (Acari: Ixodida: Argasidae) is described from a single specimen preserved in amber from New Jersey. The amber is dated as Turonian, 90 94 mya, and thereby doubles the age of the oldest fossil in the mite order Parasitiformes. The specimen shows general characteristics of the genus Carios, but is unique because of its pattern of dorsal setae, featuring a double row of posterior marginal setae. Earlier hypotheses that Carios arose after the isolation of South America are challenged but not rejected by the discovery of this fossil. Salvaging these hypotheses seems most compatible with dispersal on birds, an idea consistent with the presence of a small feather in the same outcrop in which the tick fossil was found.