Due to being less well-studied compared to H. colei and being contemporaneous, it is possible that H. bruxelliensis and H. deshayesi are synonymous with each other. H. colei and H. deshayesi were originally placed in HemirhynchusAgassiz, 1844, which was found to be preoccupied by a junior synonym for the bird genus Suthora (HemirhynchusHodgson, 1843). Both these species were thus reclassified into the genus Homorhynchus, originally coined as a monotypic genus by Pierre-Joseph van Beneden for H. bruxelliensis.
Unlike most other early billfish, which had equally long upper and lower jaws, Homorhynchus had an elongated upper jaw and a significantly reduced lower jaw, the same as is seen in modern billfishes. Otherwise, it closely resembles the closely related, contemporaneous billfish Palaeorhynchus.