Pierre's Armina sp.
Pierre's Armina sp. with lunch.
Pierre's Armina sp.
Armina gilchristi
Armina gilchristi
All photos Guido Zsilavecz.
After receiving a photo by Pierre Niehaus in early February 2006 (see the Q and A section) SURG has been attempting to find this species. Peter Southwood found the right area, with many sea pens on which the species feeds (other Armina are known to feed on such sea pens, so Pierre's photo which shows one right next to one allows us to deduce that this species does so too), but did not find any. On a recent dive in the same area we were luckier, and managed to find four over two dives. Of those, three were only partially burried in the sand, the third one was covered. The first and second photo shows it feeding on a sea pen. The length of the various individuals ranged from 4.5 to 7 cm. They were found on a flat, mostly featureless sandy plain, 400m offshore from Windmill, in 12 to 15m depths. This is most likely to be an undescribed species.
On the way back, nearly out of air, Peter somehow managed to spot the other species - in fact, he spotted three in very quick succession. Lack of air meant we had to return, but we immediatelly changed tanks and headed out again, and found quite a few. From the texture of the ridges we concluded it most likely is A. gilchristi. According to the reference material, it was previously only found when dredged from 70 to 80 m deep waters, although there is a record of one from 30 m. While the image in Gosliner's book shows a blue individual, we believe this is a lack of light, rather than a truly blue animal. If this is indeed A. gilchristi, it is clear that it has a greater depth range than previously thought, given that we found so many. Sizes of this species ranged from 3.5 to 4.5 cm. All were seen on the sand surface, barely dusted over by sand. While some attempted to dig, none went really far below the surface, unlike Armina sp., which does go completely underground.
Nudibranchs of Southern Africa - a guide to the opisthobranch molluscs of southern Africa, T Gosliner, 1987.