Global Distribution The range of Porites horizontalata is somewhat restricted longitudinally from the Maldives in the west to the central Pacific in the east and latitudinally from south of Japan in the northern hemisphere to New Caledonia in the southern

Taxonomy Taxonomic issues: Porites is known to be morphologically plastic and multiple sympatric species frequently exhibit intergradation of skeletal characteristics. Only limited molecular genetic analysis has been performed on the Porites thus far. In the most comprehensive, Forsman et al. (2009) identified inseparable clades that contain multiple morphological species, in some cases with morphological species that span more than one clade. However, such genetic work has not been conducted on Porites horizontalata. Laminar parts of colonies resemble those of Porites vaughani. Branching parts of colonies may have corallites arranged in a Porites rus-like pattern. Calice characters are closest to Porites eridani branches (Veron, 2000).