N. delessertiana was long considered to be merely a form of the much more common and much more widely distributed species Neverita duplicata. In 2006 a paper was published which made it clear that Neverita delessertiana is a different species than N. duplicata.[2]
Distribution
This species is found in the United States in Florida, Alabama, Mississippi, Louisiana and Texas.[3]
^Huelsken, T. et al. (2006) Neverita delessertiana (Recluz in Chenu, 1843): a naticid species (Gastropoda: Caenogastropoda) distinct from Neverita duplicata (Say, 1822) based on molecular data, morphological characters, and geographical distribution. Zootaxa, 1-25. PDF.