August 23, 2001
From: Yasuhiro Shirai
Thank you for your message. I saw Mr. Nishina's photos of Siphopteron cf. nigromarginatum. I took some photos similar to Mr. Nishina's individuals in spring of this year and last year at Tanabe Bay, Kii Peninsula. But my individuals of photos have bold marginal line. These photos are of different individuals. Are these Siphopteron nigromarginatum? If not, could you please identify them for me?
Date: May, 2000 and 2001
Place Tanabe Bay, Kii peninsula, Japan
Depth: 7 to 15m
Size: 5 to 10mm
Shirai, Y., 2001 (Aug 23) Siphopteron nigromarginatum? from Kii Peninsula. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5011
Thanks for these photos which are indeed Siphopteron nigromarginatum. It is apparently quite variable in colour with the black parapodial border being very heavily pigmented in some animals and almost absent in others.
I don't know if you have seen the very large new book by Dr Okutani (2000) - Marine Mollusks in Japan. In it, this species is identified as Gastropteron bicornutum Baba & Tokioka, 1965, but I think this is a misidentification. In that animal the posterior visceral hump has a secondary papilla (hence the name bicornutum), and the brief colour notes in the original description mention orange spots rather than an orange background colour. There is also no mention any black pigmentation.
A juvenile Siphopteron nigromarginatum
From: Takao Urasawa, February 11, 2006
Siphopteron nigromarginatum from Hachijo
From: Nishina Masayoshi, August 12, 2002
Re: Siphopteron cf. brunneomarginatum
From: Nishina M. & J. Imamoto, August 4, 2001
Re: Siphopteron from Japan
From: Terry Gosliner, August 2, 2001
Siphopteron cf. nigromarginatum from Japan
From: Nishina Masayoshi, August 1, 2001