Pleurobranchus areolatus

Photo courtesy of Ali Hermosillo
Puerto Vallarta, Mexico

Pleurobranchus areolatus (Morch, 1863)

Pleurobranchus aerolatus, often called the warty side-gilled slug, is one of the largest species of side-gilled slug, or Pleurobranch, on the Pacific coast of North and Central America. Specimens in California and Brazil have been documented at over 150 cm in length. This species has a very large distribution, which includes the Caribbean, tropical West Africa and the eastern Pacific.

This species first showed up in the California Channel Islands after El Nino in the late 1990’s. I received almost a dozen inquiries about its identity from interested Branchers, but at that time I was convinced it was an undescribed species. Slugo buddies Terry Gosliner and Hans Bertsch convinced me otherwise, that it was P. areolatus {see BOW Week 71} where I referred to it as Pleurobranchus sp.

In any event, discussions continue on the variability of Pleurobranchus aerolatus, and whether the number of variations in the Caribbean, are possibly separate species. See Bill Rudman’s response to my note on his Forum, January 23, 2001. Concerning the identification of the Pacific specimens, those found in Mexico like Ali’s above match the poorly described Caribbean species But those found further north in California, in more temperate waters, have a smoother mantle, and lack white specks like Eric’s animals in BOW 71.

Steve Drogin just found this handsome specimen during a recent trip to the northern area of the Sea of Cortez by Puerto Penasco.

I must say, my heart leaps every time I turn over a rock and find one of these beauties.

Puerto Vallarta, Mexico
March 2005

Ali Hermosillo and Dave Behrens Author: Pacific Coast Nudibranchs Co-Author Coral Reef Animals of the Indo Pacific Proprietor of Sea Challengers Natural History Books Send Dave mail at dave@seachallengers.com

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