The dark spot in the middle of the dorsum causes this species to resemble Berthella africana, which is known from East Africa and the Canary Islands. Further study is needed to determine if they are actually the same. We have found Berthella caledonica in the Marshalls at Enewetak, Utirik, and Kwajalein Atolls, and in the Hawaiian Islands as well. John and Lynette Flynn report B. caledonica from Rongelap Atoll. Similar specimens from Okinawa photographed by Robert Bolland are also figured on the Sea Slug Forum (as Pleurobranchus caledonicus). In the Marshalls, specimens are usually found under rocks on lagoon reefs, pinnacles, or the seaward reef at depths of 2 to 20 meters.
The specimen below is one of the largest found at 55mm long.
Here is a young specimen measuring only 12mm in length. It was found in a Kwajalein Atoll seaward reef ledge at night at a depth of 12m on 18 October 2008.
The smaller specimen below was a bit of a puzzle since it lacked the dark middorsal spot. However, other aspects of color suggest it is indeed this species.
The 34mm specimen below was found under a rock on a Kwajalein lagoon reef in 5m of water on 19 September 2010.
This side view reveals the gills under the right mantle margin.
Specimens measuring 15 and 33mm were found and photographed by John and Lynette Flynn at Rongelap Atoll.
Also from Rongelap by John and Lynette Flynn is this 45mm individual that we are tentatively including as Berthella caledonica (next three photos). The tiny brown circles match in all of these animals, but this specimen lacked the distinct brown dorsal spot usually present in adults. Their photo of the bottom of the foot shows an interesting honeycomb pattern that I do not recall from typical B. caledonica, although I admit I cannot remember if I ever looked.
This one shows the gills at left.
Created 2 February 2007
Updated 3 May 2021