Can you id this California crab

[archman]

Dr. Wicksten's a world-renowned decapod taxonomist (you'll see her listed in the Caribbean Humann guide). The only time she's been wrong is when she creates new species out of existing records. If she says it's P. tuberculata, it's P. tuberculata. She pulled out a book from 1927 to cross-verify... she had the thing pegged in less than three minutes, including time to go back to her office to show me the drawing out of the book. I didn't check to see what size range was listed from her refs, though.

She even knew all the names of the other possible crab names previously posted, and summarily trounced each one while I sat there. Now that's just whacked!

 

[John H. Moore]

A positive ID on that one photo? It's always hard to tell from one ID photo in a book, but the Pyromaia tuberculata photo (Jensen) has a leg:carapace ratio much larger than the photo attached above. Of course, it's all a matter of perspective and with only one, oblique photo.

Still think it looks like Herbstia -- which I've personally handled in a lab. Never seen Pyromaia tuberculata... doesn't mean it's not there, though!

John

 

[archman]

I'd be suspicious too if someone stared at a photo for ninety seconds and tagged it while the rest of us have sat in stupefaction all week. Unless it was a deepwater starfish, and then I'd do the same instant I.D. also. It's taxonomist black magic.

She trounced Herbstia along with all the others without even thinking about it. California fauna is her particular forte. I'll ask her tomorrow about the size and ratio questions... maybe she got overeager. I STILL haven't witnessed her wrong about a crab yet! Or shrimp, or anemone, pennatulacean, bivalve, siphonophore, good god make it stop!

 

[John H. Moore]

I should add that I'd be just as content with an ID of Erileptus spinosus. Only issue there for me is the white fuzz. Erileptus has fuzz, but generally not white. Herbstia is known for white fuzz (I've seem some completely covered in it). If we had a shot from the top, we could tell pretty immediately.

Meanwhile, the photographer may be able to supply more resolution. I've asked...

 

[archman]

I am pasting Dr. Wicksten's response regarding most peoples' questions on the crab.

The definitive work on spider crabs of the western U.S.A. is the book I showed you--Brachyura of the Pacific Coast of America, Oxyrhyncha, by John S. Garth. 1958, University of Southern California, Allan Hancock Pacific Expeditions Vol. 21. The pictorial guide by Jensen does NOT show all the spider crabs of California, nor was it intended to be the last word in taxonomic guides. As for the other species:
Erileptus spinosus is a very tiny crab, entire legspan could fit on a quarter. It only lives along the coasts of the California islands or in areas of coarse shelly sand and fairly strong surf or currrents. The carapace bears characteristic knobs and constrictions. Herbstia parviforns lives under rocks and in cracks. Take a closer look at the carapace, which is somewhat rounded in shape. The walking legs beaar rows of spines on the meral segments. The proportions of the walking legs to the body are shorter in comparison to the crab in the picture. The crab in the picture seems to bear algal decoration. Herbsita never does. As for the size-- Garth says that the largest male of P. tuberculata has a carapace length of 21.7 mm, but if one includes the legspan, the animal could have a width of about 4 inches.

Mary Wicksten ( I probably am the reigning authority on all decapod crustaceans of California)

In case nobody noticed, she gets rather defensive about crabs... after six years in her lab I've learned to defer anything I'm not positive of to her.

 

[John H. Moore]

Grrrr.... I'm all ready to tell you where she's wrong, but I'm not able to! I thought E. spinosus was larger. In fact, that means there's an E. spinosus-like crab in San Diego which is bigger and very similar! Wonder what it is?! Not Pyromaia tuberculata certainly. Wish I had my Morris, Abbott & Haderlie with me... Jensen lists E. spinosus as max 0.3 inches... although I've personally seen critters significantly larger than recorded size ranges... Hmmmm.

Herbstia: yes, spines - that's a real problem. But also very decorated by a white sponge. Wicksten says the unknown critter decorations are algal...??? Certainly they're white. Algal or sponge? Yes, Herbstia lives in things... but what's just outside the photo?

If in fact the carapace size was as reported, it's a size problem for Pyromaia tuberculata as well....

Hmmmmmmm.... wish we had a dorsal view of this guy. Oh well....

Perhaps we'll have to come up with some more unknown crabs just to play this fun game again!!!!

John

 

[John H. Moore]

OK, how many seconds does it take her to get this one?

big

 

[John H. Moore]

Hannah, who hates to be left out of discussions about marine life, says, "No, no, no, you're all wrong! The mouth of the starfish is located here..."

 

[drbill]

I certainly agree with Dr. Wicksten that Jensen is by no means a definitive work. Its major benefits IMHO are the photos. And I'm sure she is a far more authoritative expert on the decapods here than I am.

Here is a case where an actual collection would have resulted in a positive ID vs a photo which has limited representation. Any time I take images I try to get several different angles to show different features. However, pictures are often insufficient to really determine the characteristics that lead to successful identification.

Dr. Bill

 

[archman]

OK, how many seconds does it take her to get this one?
big

very funny. I'd probably get my butt kicked if I brought in another crab photo this week. :death2:

FYI she has for some time been trying to publish a new set of descriptions for California decapods. A lack of interest has been shown by various west coast nature publishers.