Kudoid parasites are significant pathogens of marine fish. In the past, specific identification has been difficult due to a paucity of detailed morphological and biological information provided in the original description of some species. However, the introduction of DNA analysis has dramatically improved diagnosis. For morphological characterization, this paper proposes a new set of schematics including additional measurements to give a more thorough description of spore morphology, and provides evidence for uniqueness of 4 new species: Kudoa gunterae n. sp. (from 10 pomacentrid species and 1 apogonid species), K. kenti n. sp. (from 4 pomacentrid species), K. paraquadricornis n. sp. (from 4 carangid species), and K. whippsi n. sp. (from 8 pomacentrid species and 1 apogonid species). Subtle morphological differences found between closely related species were reflected in their genetics, with increased resolution provided by the large subunit, compared with that of the small subunit, of the ribosomal DNA gene region. This article proposes comprehensive requirements for species descriptions within the Kudoidae that incorporate biology, morphology, and genetic sequence.