Questions remain about the taxonomy and distribution of geographically widespread species in the circumtropical gobiid genus Awaous. Previous work that placed two species in synonymy on the basis of morphological characteristics effectively redefined the range of Awaous guamensis to include distant locations from Hawai'i and Guam to the islands of South-East Melanesia. Here we evaluate the synonymy of A. guamensis and A. stamineus through phylogeographic analysis of mitochondrial DNA sequence variation and morphological comparisons of Hawai'i and Guam populations. Phylogenetic assessments show clear separation of molecular characteristics, and morphological analyses illustrate statistically significant phenotypic differences indicating that the populations represent distinct evolutionary lineages. Based upon genetic, morphological, and geographic distributional differences, we recommend that Hawaiian populations be recognized as a distinct species, and reversion to the previous nomenclature of Awaous stamineus.