Phestilla melanobrachia from Indonesia

November 25, 2009
From: Helene Caillaud


Here is a picture of a nudibranch, that i'm trying to identify.

I'm hesitating between Phyllodesmium briareum or Phestilla melanobrachia. Could you help me to identify it

Locality: Bali, 20 metres, Indonesia, 8 october 2009, sandy area, muck dive. Length: 30 mm. Photographer: Helene Caillaud.

Thank you very much,

from France

Caillaud, H., 2009 (Nov 25) Phestilla melanobrachia from Indonesia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Helene,

This is the black colour form of Phestilla melanobrachia which gave the species its name [melano = black]. I think the very blue look is caused by the way light is bent by the fine cilia on the cerata - you get a similar effect with black velvet cloth.

We usually think of this species as bright orange, but when they feed on the black form of the coral Tubastraea the digestive gland in their cerata fills up with black material. However, as we can see in the close-up, the orange pigment on the rhinophores and oral tentacles stays orange as it is based on skin pigment. As I discuss elsewhere on the forum [see coral feeding] species of Phestilla drop their cerata as a defensive strategy. In the close-up you can see two rows of small replacement cerata growing amongst the full size ones.

Best wishes,
Bill Rudman

Rudman, W.B., 2009 (Nov 25). Comment on Phestilla melanobrachia from Indonesia by Helene Caillaud. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

  1. Who can identify?
    From: Carmen Obrist, December 23, 2009
  2. Phestilla melanobrachia from Thailand, with parasites
    From: Marcel Tanke, February 9, 2009
  3. Phestilla melanobrachia from sthn Queensland [2]
    From: Gary Cobb, December 17, 2008
  4. Phestilla melanobrachia? from sthn Queensland [1]
    From: Gary Cobb, December 17, 2008
  5. Phestilla melanobrachia? from Singapore
    From: Toh Chay Hoon, November 3, 2008
  6. Parasites on Phestilla melanobranchia
    From: Jon Bertsch, November 21, 2007
  7. Phestilla melanobrachia from Bali
    From: Mike Krampf, August 8, 2007
  8. Re: Phestilla melanobrachia from Hong Kong
    From: Curt Swearingen, July 25, 2007
  9. Phestilla melanobrachia from the Red Sea
    From: Sven Kahlbrock, June 4, 2007
  10. Phestilla from the NOAA website
    From: Frances Clements, August 2, 2005
  11. Phestilla melanobrachia with parasites
    From: Roberto Sozzani, February 21, 2005
  12. Phestilla melanobrachia from Reunion Island
    From: Philibert Bidgrain, February 19, 2005
  13. Phestilla melanobrachia from the Solomon Ids
    From: Bruce Potter, July 21, 2004
  14. Phestilla melanobrachia in East Pacific
    From: Alicia Hermosillo, September 6, 2003
  15. Phestilla melanobrachia & parasites
    From: Lisa Malachowsky, May 12, 2003
  16. Phestilla melanobrachia from Myanmar
    From: Mary Jane Adams, March 25, 2003
  17. Phestilla melanobrachia from Malaysia
    From: Kheong Sann Chan, April 18, 2002
  18. Phestilla melanobrachia from Hong Kong
    From: Leslie Chan, July 17, 2001
  19. Phestilla melanobrachia from Hong Kong
    From: Bill Rudman & Brian Darvell, July 17, 2001

Show factsheet and all related messages