Roa haraguchiae is the newest species of Chaetodontidae and adds a sixth member to the deepwater Roa genus of butterflyfish. The description of an official new species is usually very exciting but it’s an even more special occasion when it’s a butterflyfish.
The Roa genus is interesting in that it includes members that are found both in very deep water of more than 300 feet but also includes a few species that are sometimes encountered at recreational SCUBA depth above 100 feet. Roa modesta is the shallowest member and occasionally available in the aquarium hobby while the most dramatic species, Roa excelsa is rarely offered for sale to rare aquarium fish collectors.
All of the species of Roa generally have a high body profile and a pattern of alternating white bars on a dark body, with also display varying degrees of light brown, to burnt orange to nearly yellow on the margins of the dark patches. The newly minted Roa haraguchiae is most closely related to Roa rumsfeldi but is the most monochromatic of all with dark brown bands when the fish are small with juvenile coloration but presumably will lighten up in adult specimens.
Although the Roa genus is very conservative in its appearance, there are subtle, noticeable differences in the bands, dorsal and pelvic fins that are easy to spot if you know where to look. Thankfully the description of Roa haraguchiae includes some nice closeup comparisons of the new species with its congeners.
Roa haraguchiae was described from eight specimens collected in very deep waters of Japan, between 146 and 162 meters deep, 479 to 531 feet but it has been photographed as ‘shallow’ as 230 feet. Although this most likely precludes this species from being collected alive for private or public aquariums, we can probably look forward to a couple more new Roa species getting officially described from deep waters in other parts of the world. [Ichthyo. Research]