©Scott Johnson, All Rights Reserved 1996

Chromodoris rubrocornuta

Chromodoris rubrocornuta, Rudman, 1985

Chromodoris rubrocornuta is reported from Queensland, Hong Kong, and Bikini Atoll in the Marshall Islands. I found 10 of them at Bikini, all of them looking about the same. These are the only typical C. rubrocornuta I've found in the Marshalls ( To better acquaint the reader with this area in a geographic sense, the PARC Map Viewer has been enabled for the various site locations). Now consider an image taken apparently of the same species from Rongelap Atoll , Marshall Islands, about 75 or so miles east of Bikini. Only one of these was found, and it differed from the typical rubrocornuta in the rhinophore and gill coloration--pure bright white instead of reddish.

To make matters a tad more complicated, consider another image that is apparently the version from Kwajalein Atoll, a couple of hundred miles south of Bikini and Rongelap. It has the reddish rhinophores and gills, but the dorsum is lemon yellow instead of white. All 5 or 6 specimens I've found here have been of this color.

So if the Marshall Islands C. rubrocornuta are really this variable , it makes me wonder about Chromodoris galactos Rudman & Johnson, 1985, a similarly colored species, so far known only from Enewetak Atoll , about 350 miles northwest of Kwajalein (and maybe an estimated 200 miles west of Bikini ). I found over 100 specimens there, all very consistent in coloration. It is about the same size as the various rubrocornuta, and has the white dorsum, reddish rhinophores and gills, and orange margin. The maroon submargin, however, is speckled with opaque white instead of being broken and irregular but unspeckled (with the maroon and white segregated into patches) as it is in all the rubrocornuta.

If these are the same, it's interesting that atolls so close together would have such different color forms.

Photos and Text courtesy of:

Scott Johnson

Hawaiian Nudibranchs
Kwajalein, Marshall Islands
Send Scott E-Mail at johnson@kmrmail.kmr.ll.mit.edu

For those of you interested in the photographic background information of the images, the following may be of interest!
Camera System: Nikonos II with 1:1 extension tube

Strobe: Oceanpro 2003 strobe

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