A previous observation suggested that a novel phenotype of lionfish supraocular tentacle is evolving rapidly in the Red Sea and Indian Ocean. We confirm the existence of this phenotype in high prevalence in invasive populations of lionfish in the Western North Atlantic. Observations of individual lionfish from the Atlantic populations indicate that supraocular tentacles are more prevalent on juvenile and young adult lionfish suggesting this characteristic is size specific and is not associated with a genetic lineage. The high prevalence of this novel phenotype in the Atlantic may be a founder effect rather than continued selection. Genetic analysis further supports this conclusion as this phenotype is present in two Pterois species found in the Atlantic.