Gymnodoris sp. undescribed
This week the Webmaster walks the plank in terms of introducing a new description by the folks up at Nudibranch Central, California Academy of Sciences.
Well, look on the bright side of the presentation in that you will be introduced to a new paper although my conclusions based on the paper may be out of kilter as the saying goes! Two of the three descriptions in the paper are very similar in appearance (Gymnodoris brunnea and Gymnodoris pseudobrunnea ). The photographs in the paper serve science well but I wanted the image in this presentation to go beyond merely a basic portrayal to one that illustrates the animal in exacting detail! To accomplish this goal, I turned to buddy and ace underwater photographer, Jim Black !
The taxomonic key I hung my hat on was the presence of white internal organs that appear at the gills in a position indicative of G. pseudobrunnea .
To quote the authors "... The features that best differentiate these species externally include the shape and position of the white patch visible through the skin on the dorsal side of the animals, and the external visibility of the intestine. The margin of the white patch is far more irregular in shape in G. pseudobrunnea than it is in G. brunnea. Also, in G. pseudobrunnea, the white patch appears at the gills and posteriorly, whereas in G. brunnea, the white can be seen forward of the gill and posteriorly. In G. brunnea, the intestine is visible through the skin as a dark arch; this does not appear to be visible in G. pseudobrunnea..."
Sea Slug identifications are inherently problematic based on visual markers. In this case we can probably be assured it is one of the two descriptions, but which one? It's all in the eye of the beholder and I would certainly entertain other opinions as to which?
Well, the responses were quick in coming in. Nudibranch Central has indicated that the subject of this week's presentation is neither G. brunnea or G. pseudobrunnea and has also been collected at Dive Site Basura for those who are familar with the Anilao area. It is presently undescribed ! So there you have it folks!
Reprinted from: Williams, Gary C., and Terrence M. Gosliner, eds. 2014. The Coral Triangle: The 2011 Hearst Philippine
California Academy of Sciences, San Francisco, California 94118, USA. Published 15April14.
Three New Species of Gymnodoris Stimpson, 1855 (Opisthobranchia, Nudibranchia) from the Philippines Vanessa L. Knutson and Terrence M. Gosliner Department of Invertebrate Zoology and Geology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA 94118;
Jim Black is retired from US Airways after 37 years as a pilot..., flying Captain on an Airbus 330 Internationally.
Diving since 1970...with over 7500 dives logged. Shoots Nikon D-300 in Subal Housing with Ikelite strobes. Macro Mate on 105mm for supermacro.
Jim's photography has been featured in a number of books and publications including Helmut Debelius' Nudibranchs and Sea Snails of Gosliner, Behrens and Williams Coral Reef Animals of the Indo-Pacific. A photo of Jim petting a shark in "Sleeping Shark Caves" off Isla Mujeres Island, Mexico, taken by Amy Foster his significant other, recently appeared in Dave Behrens' Diving Guide to Cozumel, Cancun & The Riviera Maja.
Jim has been a solid supporter of the Slug Site since day one. His countless contributions put him near the top of the list of photographers who have greatly expanded our knowledge of sea slugs. There are a lot of kids in the formative stage of their education who are getting their first introduction to our sea slug friends via the great photographs Jim and other contributors have made to the site. My hat is off to Jim for making this presentation possible!
Send Jim email at firstname.lastname@example.org