Image via Carl Williams

Given the crayfish’s distinctive appearance, scientists were surprised that it hadn’t been discovered earlier. However, it appears that this newly described species of crayfish is very rare. Via New Scientist’s Short Sharp Science Blog:

Named Barbicambarus simmonsi after the scientist who first spotted it, it is only the second member of the genus to be found. It is rare which may explain why it went unnoticed for so long.

Chris Taylor at the Illinois Natural History Survey and Guenter Schuster at Eastern Kentucky University in Richmond hurried to Shoal Creek after hearing reports of an unusually large crayfish. After two hours of fruitless searching they were about to give up, but decided to turn over one last rock and discovered their first specimen.

More on Barbicambarus simmonsi via ScienceBlog.com:

Its closest genetic relative, once thought to be the only species in its genus and discovered in 1884 about 130 miles away in Kentucky, can grow almost as big as a lobster.

The researchers found their first specimen under one of the biggest rocks in the deepest part of a creek that has been a (literal) stomping ground for aquatic biologists for at least half a century. The new species is described in a paper in the Proceedings of the Biological Society of Washington.

The new crayfish belongs to the genus Barbicambarus, which in addition to being big is very distinctive. Most notably, Barbicambarus have unusual “bearded” antennae; the antennae are covered with a luxurious fringe of tiny, hair-like bristles, called setae, which enhance their sensory function.

“This isn’t a crayfish that someone would have picked up and just said, ‘Oh, it’s another crayfish,’ and put it back,” said University of Illinois aquatic biologist Chris Taylor, the curator of crustaceans at the Illinois Natural History Survey and a co-discoverer of the new species with Eastern Kentucky University biological sciences professor Guenter Schuster. “If you were an aquatic biologist and you had seen this thing, because of the size and the setae on the antennae, you would have recognized it as something really, really different and you would have saved it.”

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Both men suspected that this was a wayward member of the originally discovered species, Barbicambarus cornutus. B. cornutushad never been seen that far south, but the researchers knew that crayfish have been moved great distances in the bait buckets of itinerant fishermen or by those interested in commercially rearing crayfishes.

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In the lab, Schuster quickly realized that the physical characteristics of the new crayfish differed in significant ways from those of B. cornutus. Taylor took tissue samples and compared the specimens’ DNA to that of B. cornutus.

“And the DNA said just what the morphology said: This thing is pretty different,” Taylor said.

And rare. The researchers made several more trips to the area before they were able to collect enough specimens to confirm what they already suspected: The giant crayfish of Shoal Creek was a new species. They named it Barbicambarus simmonsi, in honor of the TVA scientist who had collected the first specimen.

Later trips to the region confirmed that B. simmonsi was also present in the southern reaches of Shoal Creek, just north of where it drains into the Tennessee River in northwest Alabama.

Most people are shocked to learn that there are about 600 species of crayfish in the world, Taylor said, with more than half of those occurring north of Mexico. Alabama and Tennessee are hotspots of crayfish diversity, he said.