Hoplodoris armata? in Perth West Australia

July 13, 2006
From: Tom Davis

Hi Bill

We have seen a large nudibranch a couple of times that we have been unable to identify from the books we have. The nudibranch looks like Hoplodoris armata?. We have seen two colour variants and I would appreciate it if you could help with their identification.

Upper Photo: Approx. 12 cm in length. Spotted at Rockingham wreck dive trail, Rockingham, Perth, West Australia on 15 April 2006 in 11 m of water.

Lower Photo: Approx. 8 cm in length. Spotted at BHP jetty, Naval Base, Perth, West Australia on 26 December 2005 in 7 m of water

Locality: Cockburn Sound, Perth, 7 m and 11 m, West Australia, Indian Ocean, 26 December 2005 and 15 April 2006, Silty bottom. Length: 8 cm and 12 cm. Photographer: Nicola Davis.

Both sites are in the Cockburn Sound which also has major berths for the Port of Fremantle. Could the Nudibranchs have come from Japan/Korea in ballast water?

Tom Davis

tom.davis@worleyparsons.com

Davis, T.R., 2006 (Jul 13) Hoplodoris armata? in Perth West Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16739

Dear Tom,
They certainly look like a species of Hoplodoris, and certainly if they were from the northeast Pacific I would have no difficulty in identifying them as H. armata from their colour pattern, shape, and size. I would appreciate some feedback from anyone familiar with living H. armata.

If they are this species it is a worrying development, for as you suggest, it would probably mean they have arrived in ballast water. While they may not cause environmental problems, it would be unlikely that they were the only larvae to arrive, and as we know from Tasmania and Port Phillip, Victoria, Australian waters have proved fertile territory for a number of invertebrate species which are causing untold damage to the marine environment.

Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Jul 13). Comment on Hoplodoris armata? in Perth West Australia by Tom Davis. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16739

Factsheet

Hoplodoris armata

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