Phestilla melanobrachia in East Pacific

September 6, 2003
From: Alicia Hermosillo

Dear Bill,
I am looking for Phestilla melanobranchia around here (Bahia de Banderas, Pacific Coast of Mexico), I have some evidence that even though it is an Indo Pacific species it might be found on our side.

One specimen of the species was found in La Paz many years ago.

A few days ago I heard of someone who had, SO VERY WRONGLY, collected a rock with Tubastrea coccinea for his aquarium (fact that I totally dissaprove of and even reported to the ecology offices) ... anyways, his "beloved piece" (meaning "his" coral, sorry, I do not like aquarists much) was slowly deteriorating and he told me that he saw the nudibranch that eats them one night.

Source of information aside, that is the second report I have heard of Phestilla melanobranchia being a nocturnal creature and the second report of the species in our Pacific. I have been able to find many other cryptic critters but not this one ... Do you (or anybody out there) have any information about its habits (nocturnal) or seasonality, even some searching tips for it that might help me find it? (Incidentally, I have the same problem with Phestilla lugubris though this one I have seen in Panama).

I appreciate your help

Hermosillo, A., 2003 (Sep 6) Phestilla melanobrachia in East Pacific. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Ali,
Firstly, its a common error to call this species melanobranchia [= black gills] when the correct spelling is melanobrachia [= black arms]. Larry Harris did a lot of work on Phestilla melanobrachia many years ago [see Fact Sheet for references] and as I discuss in an earlier message he found that it preferred, or at least was found most commonly, in broken off bits of Tubastraea lying on the substrate beneath large intact colonies. In general though, these large coral-eating species seem to be quite a catch for fish and you seldom find large animals in the field, and if you do they usually hide in crevices or under the base of the coral colony during the day. Although I sympathise with your feelings towards some aquariists, keeping some species in aquarium conditions is very useful. As I discovered many years ago, and aquariists have found out recently, a good way to find nudibranchs with specialist feeding habits is to keep the food in an aquarium for some time. If there is a nudibranch feeding on that particular colony - coral or soft coral - are two obvious choices, then they are able to grow without the danger of being picked off by fish. I was able to produce multiple generations of Phestilla lugubris, Phestilla minor and Cuthona poritophages by keeping small Porites colonies alive, in somewhat primitive aquarium conditions.

I suspect if you could find broken off pieces of Tubastraea it might be worth trying to keep them alive in an enclosed aquarium system. In this way if there are invisible juvenile nudibranchs present, thye ould have a chnace to grow to visible size.

Concerning Phestilla lugubris in Panama. I described some specimens of Phestilla from Panama as a new species Phestilla panamaensis. My argument was that its radular morphology was, in my opinion, rather different from the radula of Phestilla lugubris which was a constant shape from east Africa to eastern Australia. Terry Gosliner is of the opinion that it is just Phestilla lugubris. I suspect we will need to learn a lot more about their repective biologies, and perhaps their DNA before we can be sure one way or the other.
Best wishes,
Bill Rudman

Rudman, W.B., 2003 (Sep 6). Comment on Phestilla melanobrachia in East Pacific by Alicia Hermosillo. [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 Indonesia
    From: Helene Caillaud, November 25, 2009
  3. Phestilla melanobrachia from Thailand, with parasites
    From: Marcel Tanke, February 9, 2009
  4. Phestilla melanobrachia from sthn Queensland [2]
    From: Gary Cobb, December 17, 2008
  5. Phestilla melanobrachia? from sthn Queensland [1]
    From: Gary Cobb, December 17, 2008
  6. Phestilla melanobrachia? from Singapore
    From: Toh Chay Hoon, November 3, 2008
  7. Parasites on Phestilla melanobranchia
    From: Jon Bertsch, November 21, 2007
  8. Phestilla melanobrachia from Bali
    From: Mike Krampf, August 8, 2007
  9. Re: Phestilla melanobrachia from Hong Kong
    From: Curt Swearingen, July 25, 2007
  10. Phestilla melanobrachia from the Red Sea
    From: Sven Kahlbrock, June 4, 2007
  11. Phestilla from the NOAA website
    From: Frances Clements, August 2, 2005
  12. Phestilla melanobrachia with parasites
    From: Roberto Sozzani, February 21, 2005
  13. Phestilla melanobrachia from Reunion Island
    From: Philibert Bidgrain, February 19, 2005
  14. Phestilla melanobrachia from the Solomon Ids
    From: Bruce Potter, July 21, 2004
  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