The Polyphysaceae is a well-studied family of green algae occurring in tropical and warm-temperate regions around the world. One of its species, Parvocaulis exiguus (Solms-Laubach) S. Berger et al. (Phycologia 42: 506-561, 2003), has previously been reported from both the Indian and the Pacific Oceans. This report presents the first record of Parvocaulis exiguus from the Atlantic Ocean. It was collected at 18 m depth from rocky substrata surrounded by seagrass off the Dutch Windward Caribbean island St. Eustatius. Owing to its small size and close resemblance to co-occurring species, it is possible that this species has been previously overlooked in the Atlantic. Although Polyphysaceae have been intensively studied in the Caribbean and other Atlantic regions, this is not the case for subtidal algal vegetation on St. Eustatius. Parvocaulis exiguus could have been present for a longer time around St. Eustatius or it could have been introduced with shipping. Future investigations may show if Parvocaulis exiguus will be observed in additional locations in the Caribbean.