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Limulus Australis

Jo O'Keefe Copyright 2013. Photos may be used for educational purposes only. Contact me with inquiries.

In 1818 entomologist Thomas Say identified a Horseshoe Crab in the Southeast and in Florida -- not yet a state -- that had five spines in a row across the top of its opisthosoma. He named it Limulus australis and said he thought it was a separate species. Here is a link to the journal entry: Journal of the Academy of Natural Sciences.

During 2013 DNA analyses are being conducted to determine if it is distinct species. Most scientists think it is a morphological variant. It is, in fact, referred to as "the variant." Because the name Limulus australis has not been verified, using the phrase "the variant" is more appropriate at this time.

After I first learned about the variant, I heard that it formerly had been found in both Florida and Georgia yet now, reportedly, it was only found in Georgia. Since December I have identified the variant in the following locations:

Cumberland Island, GA
Sapelo Island, GA
Wassau Island, GA
Edisto Island, SC
Waties Island, SC
Sunset Beach, SC
Masonboro Island, SC

If the variant is found to be a separate species, perhaps researchers will look for it further north.

Photos of some Limulus polyphemus and of some "Limulus australis" follow.

 
Left side of top photo
 
Right right side of top photo
 
Sunset Beach, NC, 08/28/2013
 
This is Glenn Gauvry's view 1 of L. polyphemus from the Carl Shuster collection. I see two spines counting wing-like flaps on the left and right.
This is Glenn Gauvry's view 1 of L. australis from the Carl Shuster collection. I see five spines, counting wing-like flaps on the left and right.
 
Glenn Gauvry's view 2 of L. polyphemus from the Carl Shuster collection. I see three spines, left, center and right.
Glenn Gauvry's view 2 of L. australis from the Carl Shuster collection. It appears identical to the photo labeled L. polyphemus on the left. I see three spines. Perhaps I mislabeled this image.
 
Glenn Gauvry's view 3 of L. polyphemus from the Carl Shuster collection. I see left, center and right spines.
Glenn Gauvry's view 3 of L. australis from the Carl Shuster collection. It has five spines.
 
Glenn Gauvry's view 4 of L. polyphemus (Left) and L. australis (Right) from the Carl Shuster collection. I see three spines on L. polyphemus. I am not sure where the first and fifth spines are on the right shell. See shell below in comparison.
 
This is Glenn Gauvry's view 5 of L. polyphemus from the Carl Shuster collection. I see three spines.
This is Glenn Gauvry's view 5 of L. australis from the Carl Shuster collection. I see five or six spines.
Edisto Island specimen from 2008. Five spines.
Masonboro Island, NC crab with four clear spines. Limulus australis.
Sunset Beach, NC, crab, five spines, Limulus australis
 
Waties Island, SC
Waties Island, SC
Waties Island, SC
Waties Island, SC
 
Waties Island, SC
Cumberland Island, GA, photo by Gayle Plaia
Georgia, photo by George Kash