A juvenile Siphopteron nigromarginatum
February 11, 2006
From: Takao Urasawa
Dear Dr Rudman
Thank you for you welcome advice every time.
This Siphopteron is very small. It's body is lemon yellow and red. -A beautiful colour pattern.
Locality: Laulau Beach, 6m, Saipan Northarn Mariana Islands, Pacific Ocean, 05 February 2006. Length: 1.5 mm. Photographer: Takao Urasawa
Takao Urasawa
dswith@isletwind.com
Takao Urasawa, 2006 (Feb 11) A juvenile Siphopteron nigromarginatum. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/15773
Dear Takao,
I thought at first this was Siphopteron flavum but I am pretty sure it is a juvenile Siphopteron nigromarginatum which has not yet developed all its colours. Have a look at Yasuhiro Shirai's photos [5011] which show a similar colour pattern - where your animal is translucent clear, his animal has a bluish pigment. The two red-brown spots on the edge of the parapodia are I guess the beginnings of the black line along the edge of the parapodia which give this species its name.
In many opisthobranchs black pigments start as a reddish brown colour in the juveniles. Even in adults the normal black color can be replaced by orange as occurs in Chromdoris hamiltoni and other chromodorids with black lines. I am sure a chemist could explain what is happening here, but it seems that when te black pigment is not present in sufficient quantity we get these red-browns or oranges.
Best wishes,
Bill Rudman
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