Image courtesy of Merry Passage and Phil Garner
Photo by Merry Passage
. Found on Kevin's Reef, Palos Verdes, CA by Phil Garner on December 11, 2016.
"Cratena" originally then Trinchesia, then Cuthona now Abronica.
Abronica abronia (MacFarland, 1966)

Well Happy New Year to all of you - It must be time for a new name for an old species.

This species has gone from Cratena, then Trinchesia to Cuthona, and now to Abronica. The genus level names of members of the aeolid family Tergipedidae, have bounced back and forth for years. It has been an ongoing tug-a-war across both the Atlantic and Pacific Oceans.

Finally a group of researchers (see Cella et al, below) have conducted genetic analysis across several closely related families and genera and determined that a major reorganization was necessary to more accurately depict the relationships between species. The results - No more family Tergipedidae, and in fact no more Trinchesia and only one species of Cuthona (C. nana, the type species). All the rest are now either, Tenellia, Cuthonella, Tergiposacca, Rubramoena or Abronica.

Turns out what we used to call Cuthona abronia (seen here in Merry's photo) from California waters is distinct from all other members in several larger clades now lumped under the family Fionidae. The purple bands on the rhinophores, opaque white spots on notum and opaque white and/or yellow rings on cerata unite members of this clade. Additionally, internally both Cratena abronia and Cratena purpureoannulata Baba, 1961, are distinguished by having an elongate, curved penial stylet, a feature that has not been observed in other fionids.

This reorganization is quite complex and has led to numerous name changes. You can study it yourself at this - link.

This tiny aeolid is not particularly common, but is a highly photogenic find when you do. I will miss the name Cuthona, but it nice to know that with this new research, we now have a clear systematic phylogenetic picture.

Thanks guys. Good New Year's reading. May all of you have a healthy and prosperous one.

Dave & Mike


Kristen Cella, Leila Carmona, Irina Ekimova, Anton Chichvarkhin, Dimitry Schepetov, Terrence M. Gosliner. 2016. A Radical Solution: The Phylogeny of the Nudibranch Family Fionidae. PLoS ONE 11(12): e0167800. doi:10.1371/journal.pone.0167800.

Dave Behrens
Sammamish, WA 98074
Jan., 2017
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Merry Passage worked as a genetics research scientist at Harbor UCLA for three decades. After retiring she has used her degrees from Arizona State University and laboratory experience as an aid to scuba diving. She spends countless hours researching many of the animals we find underwater. Her home office is filled with binders and identification books from algae to whales.

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From left to right, Terry Gosliner, Angel Valdes, Dave Behrens La Jolla, Calif.

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