The globally dispersed sun-coral species is _Tubastraea coccinea_ (Cnidaria: Anthozoa)

Species of the genus Tubastraea (sun corals) have spread globally over recent decades, but morphological trait identification has led to taxonomic confusion, with multiple authors proposing conflicting species identifications due to high morphological plasticity and overlapping diagnostic traits. We combined global-scale molecular phylogenetics with chromosome-level genome assemblies to resolve this taxonomic issue. Using mitochondrial and nuclear markers from 287 specimens across five ocean regions, including type localities in Bora Bora ( T. coccinea ) and Galapagos ( T. tagusensis ), we reconstructed phylogenetic relationships and inferred demographic history through approximate Bayesian computation. We also generated high-quality, chromosome-level genome assemblies for three morphologically distinct morphotypes from the Brazilian coastline. Phylogenetic and species delimitation analyses revealed two well-supported clades: a small, geographically restricted T. tagusensis clade confined to the Galapagos Islands, and a large cosmopolitan clade containing all worldwide samples, including T. coccinea from its type locality. Platinum grade Genomic analyses confirmed that the three morphotypes represent a single species, sharing a triploid karyotype of 14 chromosomes with extensive synteny and gene-tree discordance consistent with incomplete lineage sorting. Spread-route analyses identified the Centralwestern Pacific as the ancestral source, with at least three independent, human-mediated colonization events establishing populations in the Southwestern Atlantic, Gulf of Mexico, and Western Pacific. Our results definitively establish Tubastraea coccinea as the cosmopolitan species responsible for global dissemination, while T. tagusensis is endemic to the Galapagos and not involved in the worldwide spread.