The taxonomic status of the seahorse Hippocampus procerus Kuiter, 2001, type locality Hervey Bay, QLD, Australia, was re-examined based on its strong morphological similarity and geographical proximity to its congener H. whitei Bleeker, 1855, a species recorded in ten estuaries of New South Wales, Australia. Kuiter (2001) distinguished H. procerus from H. whitei by a taller coronet, marginally lower meristics, and spinier physiognomy. Meristic, morphometric, and key diagnostic morphological character comparisons from vouchered specimens of the two purported species collected from Sydney Harbour, Nelson Bay, Port Stephens, NSW and Hervey Bay, Bundaberg, and Moreton Bay, QLD did not show diagnostic differences to support species-level classification of H. procerus. Furthermore, partial mitochondrial COI sequence data from specimens sampled from known geographical distributions in NSW and Southport, QLD failed to discriminate between populations as a result of shared haplotypes, and revealed an average intraspecific divergence of 0.002%. Hippocampus procerus is hereby placed in the synonymy of H. whitei; a redescription is provided, with a revised record of its range across eastern Australia.
