Cardicola parvus n. sp. (Digenea: Aporocotylidae) infects the heart of Atlantic croaker, Micropogonias undulatus (Linnaeus, 1766) (Perciformes: Sciaenidae), in the South Atlantic Bight off Cow Island (34°38′49″N, 76°33′41″W, type locality) and Figure Eight Island (34°15′48″N, 77°44′27″W), North Carolina, USA, and off Jacksonville Beach (30°08′23″N, 81°20′52″W), Florida, USA. The new species is most easily differentiated from other members of Cardicola Short, 1953 by the combination of having a minute adult body (≤1 mm total length) that is 3.1–4.7× longer than wide, widely dispersed ventral tegumental sensory papillae, ∼180 tegumental spine rows per side of body, a spheroid anterior sucker that is apparently aspinous, an esophagus that is 38–39% of the body total length, a male genital pore that is anterior to the ootype, a uterus that transitions from ascending to descending portions posterolaterally to the ovary, and a nearly transverse oviducal seminal receptacle. The new species is the second named aporocotylid from a littoral fish of the South Atlantic Bight and the fifth aporocotylid species reported from fishes of the northwestern Atlantic Ocean.