A flea preserved in Dominican amber is described as Atopopsyllus cionus, n. gen., n. sp. (Atopopsyllini n. tribe, Spilopsyllinae, Pulicidae). The male specimen has two unique characters that have not been noted in previous extant or extinct fleas, thus warranting its tribal status. These characters are five-segmented maxillary palps and cerci-like organs on abdominal tergite X. Additional characters are the absence of ctenidia, very small eyes, a lanceolate terminal segment of the maxillary palps, legs with six notches on the dorsal margin of the tibiae, five pairs of lateral plantar bristles on the distitarsomeres, and nearly straight ungues with a wide space between the basal lobe and tarsal claw. Trypanosomes and coccobacilli in the rectum and coccobacilli on the tip of the epipharynx of the fossil are depicted and briefly characterized.