Notobryon wardi Odhner, 1936
Here is the second species of the Dendronotina family Scyllaeidae that Ali Hermosillo and I collection while on the Destiny Expedition to Zihuatanejo, Mexico. I cannot believe that Ali found this specimen under the conditions we were diving on this particular dive. We had huge swell this day, which dropped the visibility to less than 2 feet. As Ali has experienced with her collections in Puerto Vallarta, Bahía de Banderas night dives are the best if not only time to find this very cryptic species.
Notobryon is very similar to both Crosslandia and Scyllaea , from the Atlantic. Bill Rudman gives a detailed account of the internal anatomical differences. All three have two pairs of large lobes on the dorsum. Both Scyllaea and Notobryon have a ridge or crest on the tail which they as a paddle, to swim by vigorously waving it from side to side. Like Scyllaea, it has long branches gill-like processes between the mantle lobes. These gills are transparent and very hard to see in some specimens . Under the microscope you can see 3-4 long, tubular, branched gills just inside each lobe.
This species was just documented from the eastern Pacific when Ali reported it on the Sea Slug Forum. Its previous distribution was Indo-West Pacific, from Japan, Queensland and South Africa.
Thanks again to Steve Drogin for his hospitality onboard his boat in Zihuatanejo. We will see some of Steve's photos from the trip in coming BOW's.
David W. Behrens
Pacific Coast Nudibranchs
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