The western Atlantic pontoniine shrimp Ascidonia miserabilis is reported for the first time from Atol das Rocas, off Rio Grande do Norte, representing the first record of this species and the genus Ascidonia for Brazil and the south-western Atlantic. In addition, its geographical range in the Caribbean Sea is extended to Honduras and Panama. All specimens of A. miserabilis were collected from inside cryptic ascidians, Acidia spp., in very shallow water (1–2 m). Illustrations of the previously unknown colour pattern of A. miserabilis are provided for the first time.
