Janolus fuscus from northern Japan

July 9, 2004
From: Nishina Masayoshi

Dear Bill,
In response to Fraser Stanton's message [m12676] here are some images photographed by Fujita at Rausu in Hokkaido Is. in northern Japan. The first description of this species from Japan was by K. Baba (1974) from Sado (an island located in northern part of Sea of Japan). I cannot confirm any further records from that area, however, I noticed that this species is now widely distributed
around coasts of Hokkaido Island. As far as I know, this species was known to local scuba divers at least 20 years ago and they said that it's not uncommon.

DATE: Aug,2000
LOCATION: Rausu,Hokkaido Is.(northernmost island of Japan),East longitude -145,North latitude-44,
LENGTH: 20-30mm
PHOTO BY: Yoshie Fujita

About one year ago, Dr.Jeff Goddard kindly gave me some advice on this species from Japan, and he has agreed that this is conspecific. It is possibly introduced from the Pacific coast of North America.Best Regards,
Nishina Masayoshi


Masayoshi, N., 2004 (Jul 9) Janolus fuscus from northern Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/12680

Thanks Nishina,
I would appreciate a reference to Baba's record of this species in Japan. While it's possible that this species has been introduced to nthn Japan by shipping it is also possible the distribution around the nthn Pacific is a natural phenomenon. As we get a better knowledge of the fauna, quite a number of species appear to have a wide distribution in the northern Pacific down both the coast of Nth America and the coast of Asia. Goddard & Foster (2002) record it from Alaska.

Best wishes
Bill Rudman

Rudman, W.B., 2004 (Jul 9). Comment on Janolus fuscus from northern Japan by Nishina Masayoshi. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/12680


Janolus fuscus

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