Known from tropical eastern Australia, but possibly more widely spread in the western Pacific.
UPPER: Phyllodesmium crypticum Angourie, northern New South Wales, Australia. October 1979. Length 5cm. PHOTO: Bill Rudman.
LOWER: Section through a tentacle of the soft coral Xenia showing the pouches of symbiotic zooxanthellae (stained red). Xenia is the preferred food of Phyllodesmium crypticum.
PHOTO: Bill Rudman.
As its name suggests, Phyllodesmium crypticum is a very cryptic species, well-camouflaged amongst the colonies of the soft-coral Xenia in which it lives and on which it feeds. This is another of the many species of aeolid which store zooxanthellae from their food, presumably obtaining nourishment when they photosynthesise. The large sacs of zooxanthellae found in the tentacles of Xenia are clearly the source of Phyllodesmium's zooxanthellae.
This species is very similar in appearance to Phyllodesmium hyalinum, another species found in association with the soft coral Xenia. See Phyllodesmium hyalinum, for distinguishing features of the two species.
• Rudman, W.B. (1981) The anatomy and biology of alcyonarian-feeding aeolid opisthobranch molluscs and their development of symbiosis with zooxanthellae. Zoological Journal of the Linnean Society 72: 219-262.
Rudman, W.B., 1998 (October 11) Phyllodesmium crypticum Rudman, 1981. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/phylcryp
January 29, 2009
From: Dominique Horst
Concerning message #20423:
Locality: Lembeh, 8 m, Indonesia, Celebes Sea, 26 November 2008. Length: 20 mm. Photographer: Elisabeth Juan.
Many thanks and kind regards,
email@example.comHorst, D., 2009 (Jan 29) Phyllodesmium crypticum ? from Indonesia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22190
It's not that easy to separate some species of Phyllodesmium from a photo, but I suspect this is P. crypticum. In P. lembehensis the brownish zooxanthellae seem to be restricted to nodules along the edge of the cerata while your animal sems to have digestive gland branches running to the flat upper and lower surfaces as well.
September 1, 2008
From: Gary Cobb
To accompany my first message [#20422], here are a few more photos of Phyllodesmium crypticum, including one of its egg ribbon.
Locality: Alexandra Headland, 10-100 mm, Queensland, Australia, Pacific Ocean, 19 April 2004, Intertial and subtidal. Length: 5-55 mm. Photographer: Gary Cobb.
firstname.lastname@example.orgCobb, G.C., 2008 (Sep 1) Phyllodesmium crypticum from sthn Queensland . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20423
The close-up of the cerata shows the secondary and tertiary branching of the digestive gland ducts very well.
September 1, 2008
From: Gary Cobb
Hi Bill and everyone!
I see you mentioned Phyllodesmium crypticum. At Alexandra Headland intertidal area I have found many of these beautiful animals. Many egg masses too. You have to be very careful when handling this species ... it casts it's cerata at the slightest touch! In this message the animal shot on white is a 5 mm long juvenile.
Locality: Alexandra Headland, 10-100 mm , Queensland, Australia, Pacific Ocean, 19 April 2004, Intertial and subtidal. Length: 5-55 mm. Photographer: Gary Cobb.
See also Part 2 [#20423 ].
email@example.comCobb, G.C., 2008 (Sep 1) Phyllodesmium crypticum from sthn Queensland . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20422
Yes one of the problems of studying these animals is their tendency to drop off their cerata [see autotomy page]. Your photos, and the ones in the second message, show many of the characters of those species of Phyllodesmium which feed on xeniid soft corals. All of them restrict the secondary and tertiary branching of the digestive gland to the cerata, so the body wall is translucent white with only the main ducts of the digestive gland, leading from the stomach to the cerata, showing through the body wall as brown lines. By comparison, the new Phyllodesmium koehleri [see message #21841] has branches of the digestive gland throughout the body wall and even the rhinophores.
August 8, 2007
From: Ken Tucker
Concerning message #20402:
Yes, since you are interested, I have a sequence of 10 photos showing the two together, and their brief encounter. C. lochi moves across the field, eventually bumping into Phyllodesmium crypticum [first photo]. C. lochi "abruptly" changes direction, and continues on around. The second photo is perhaps a better photo if P. crypticum.
Locality: North Sulawesi, Lembeh Strait, 10 metres, Indonesia, Celebes Sea, 5 Nov 2005. Length: 2+ cm. Photographer: Ken Tucker.
firstname.lastname@example.orgTucker, K.C., 2007 (Aug 8) Re: Chromodoris lochi from Indonesia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20415
Species of Phyllodesmium lack the cnidosac filled with stinging nematocysts at the tip of each ceras, which is the first line of defence for most aeolids, and instead have a large gland at the ceratal tip producing secretions apparently to deter potential predators. Perhaps that is what caused the avoidance action in your Chromodoris.
May 28, 2007
From: Bruce Wilkie
I found this animal the other day, and I think it may be Phyllodesmium crypticum, could you please confirm the id?
Locality: Flat Rock North Stradbroke Island, 16 metres, Queensland Australia, Pacific ocean, 24 February 2007, rocky reef with sponges, hard & soft corals . Length: 15mm. Photographer: Bruce Wilkie.
Wilkie, B., 2007 (May 28) Phyllodesmium crypticum from sthn Queensland. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19626
Yes this is P. crypticum. I have added a couple of close-ups to show the branching of the digestive gland in the cerata. Your animal shows only a few scattered brown patches on the ceratal wall which suggests it is short of the unicellular algae [zooxanthellae] it gets from feeding on certain soft corals. I guess it hasn't fed for a while.
April 16, 2005
From: Binyamin Koretz
Another newcomer to Eilat: Phyllodesmium crypticum.
Locality: Eilat, Village Beach, Israel, Red Sea (Gulf of Eilat). Depth: 23 m. Length: ca. 4 cm. 02 April 2005. sea grass and patch reef. Photographer: Binyamin and Shulamit Koretz.
Koretz, B., 2005 (Apr 16) Phyllodesmium crypticum from the Red Sea. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/13485
When I first saw your photos I wondered if you had a pale version of the sacoglossan Cyerce, but the branching of the digestive gland in the cerata [see lower right photo] are characteristic of P. crypticum. As far as I can recall this has not been found in the western Indian Ocean before - another interesting find.
March 24, 2003
From: Patricia Danna
Location: Lembeh Strait, Sulawesi, Indonesia. Depth: 12m
Length: 3 to 4cm
Date: November 2001. [#c30]
email@example.comDanna, P., 2003 (Mar 24) Phyllodesmium from Indonesia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9139
I think, like your other specimen, that this is P. crypticum, but it is pretty difficult to be sure just from a photo. I have listed some of the external differences on the Phyllodesmium hyalinum Fact Sheet but two of the important differences are difficult. The position of the anus, is only useful, if it can be seen in the photos, and whether te cerata are in single or double rows can be confused if the animal has dropped a lot of its cerata - a fairly normal defensive strategy. The distinctive 'edges' to the cerata and the relatively long rhinophores, make me think this is P. crypticum, but I can't more than about 75% sure.
February 26, 2003
From: Pat. Danna
I'd be most grateful if you could help me identify this tiny nudibranch.
Photos: Lembeh Strait, Sulawesi, Indonesia. Depth 7m. Long 15 to 20mm. November 2001. [#c30]
Thanks for your help.
firstname.lastname@example.orgDanna, P., 2003 (Feb 26) Phyllodesmium from Indonesia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9138
There are a number of species of Phyllodesmium which feed on the softcoral Xenia and look very like it. I am pretty sure this is Phyllodesmium crypticum.
December 19, 2002
From: Mary Jane Adams
I can't figure this one out. I photographed it in Lembeh Strait, Sulawesi Island, Indonesia on Nov. 23, 2002. It was 15mm long.
Divesite: Hairball Too. Depth: about 15 meters.
Can you ID it for me?
email@example.comAdams, MJ., 2002 (Dec 19) Phyllodesmium crypticum from Indonesia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/8650
Dear Mary Jane,
I am pretty sure this is Phyllodesmium crypticum. Although I initially described this species from northern New South Wales in eastern Australia, later finds from Western Australia suggest it may have wide Indo-West Pacific distribution. It feeds on colonies of Xenia, and its knobbly cerata, make it very well camouflaged on its prey.
May 3, 1999
From: Clay Bryce
Is this Phyllodesmium crypticum? I am unfamiliar with this animal and is the
first I have seen, if it is indeed P. crypticum? It is from the Dampier Archipelago.
firstname.lastname@example.orgBryce, C., 1999 (May 3) Phyllodesmium crypticum from NW Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/810
I am pretty sure this is Phyllodesmium crypticum. I reported specimens of this species from the Dampier Archipelago in northwestern Australia from your museum collections in my 1991 paper. Before that it was only known from eastern Australia.