Arothron multilineatus from Ryukyu Islands, Japan. Credit: Matsuura 2016/Kimiaki Ito
It’s not every day that a new species of large pufferfish is described from Indo-Pacific coral reefs, but such is the case with the recent description of Arothron multilineatus, a girthy fish documented from Japan and the Red Sea. Reported to reach a length of nearly 18 inches and adorned in an attractive pattern of wavy lines, this is one of the more surprising discoveries in recent memory, but one not without some controversy.
Arothron multilineatus from Kagoshima, Japan. Credit: Matsuura 2016/KAUM
There are some important concerns which must be raised about the legitimacy of this newly recognized species, as the paper describing it relied exclusively on differences in its color pattern to diagnose it from others in the genus. This is particularly questionable given the limited number of specimens studied (4 from Japan and 2 photographs from the Red Sea) and the considerable differences in patterning seen across these specimens. Genetic data would have gone a long way towards supporting the author’s claims, but, unfortunately, none was included.
A. multilineatus from Miyazaki, Japan. Credit: Matsuura 2016/Masaaki Wada
The obvious question to ask here is how this sizable pufferfish has been able to elude the attention of divers, aquarists and zoologists up until now, especially considering it occurs in shallow reef habitats in some of the most well-dived locations on the planet. I’ve examined this genus in considerable detail for an upcoming article, using the extensive diver photography which exists in online image repositories, and I’ve found that specimens conforming to the description of A. multilineatus are tremendously rare. Out of hundreds of pufferfishes observed in the Indo-west Pacific, only a handful of examples can be confirmed. This is an entirely implausible population level to support a reproductively viable species, but it does support an entirely different hypothesis for what this phenotype represents. Click to view slideshow. Rare phenotypes are often a strong indication for a hybrid origin, and, for A. multilineatus, the presence of specimens in the Red Sea severely limits the possible parent species. Ruling out the entirely different-looking A. dimidiatus, we are left with two species native to these waters: the Starry Pufferfish A. stellatus and the regional variation of the White-spotted Pufferfish A. hispidus.
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