Re: Siphopteron cf. brunneomarginatum

August 4, 2001
From: Nishina M. & J. Imamoto

Dear Dr.Rudman,
I and Jun Imamoto are always surprised by your information. This kind of Siphopteron is not so rare at Hachijo Island. I said that this animal is S. brunneomarginatum with confidence, because I did not know that the kind called S. nigromarginatum existed. So I completely mixed up those species. Black and a dark brown distinction are difficult for me. I think that the color is influenced by the light.I will be very happy if you have a good photos of S. brunneomarginatum and S. nigromarginatum.

I cannot discriminate whether my animal is a S. brunneomarginatum and whether it is a S. nigromarginatum. The description about the color of the hump is helpful. Scattered orange was present on the head shield and visceral hump. Also with the naked eye, it has been checked clearly. The purple pattern(line?) of a clear metallic tone was also conspicuous. But I thought that it was a kind of color variation.

By the way, I guessed the meaning of the Latin name "nigromarginatum" as possibly meaning "black margin"? I have sent some images by Jun Imamoto of S. flavum (I guess) in a separate message.
Best Regards,
Nishina Masayoshi, Jun Imamoto

Nishina, M. & Imamoto, J., 2001 (Aug 4) Re: Siphopteron cf. brunneomarginatum. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Nishina & Jun,
These little gastropterids are difficult to see and there are quite a few similarly coloured species. Black and brown are often difficult to determine. Fortunately Clay Carlson and Patty Jo Hoff have just sent a photo of their Siphopteron brunneomarginatum so it now easier for you to see the differences.

Concerning the meaning of the Latin name "nigromarginatum" - yes 'black margin' or 'black edge' will do, Just as "brunneomarginatum" means 'brown-edged'.
Best wishes,
Bill Rudman

Rudman, W.B., 2001 (Aug 4). Comment on Re: Siphopteron cf. brunneomarginatum by Nishina M. & J. Imamoto. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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