The invalid combination Stirtonia alba (Müll. Arg.) ined., based on Arthonia alba Müll. Arg., is listed for the continental United States in several important online repositories, including CNALH, USDA PLANTS and EOL. Although Arthonia alba belongs in Stirtonia, the name cannot be used in that combination, as it is blocked by S. alba Groenh. ex Makhija & Patw., a species described from Java, Indonesia, and both taxa are distinct morphologically, anatomically and chemically. Here, we resolve this nomenclatural impasse by proposing the new name S. caribaea for A. alba. We examined further material identified as “A. alba / S. alba” from North America and the Caribbean. Specimens ascribed to “S. alba (Müll. Arg.) ined.” from North America (Louisiana, Florida) were found to be misidentifications in other genera, with only one collection confirmed as a Stirtonia. This specimen was determined to be S. punctiformis, and is here reported as new to North America, representing a northward range extension from Central America and northern South America. Therefore, the name “Arthonia alba Müll. Arg.” listed under Stirtonia in the North American lichen checklist should be removed. Caribbean material previously identified as A. alba was found to represent two species: A. alba s.str., here renamed S. caribaea, known from Cuba and St. John of the U.S. Virgin Islands; and S. borinquensis, which we describe as a new species from Puerto Rico.