New species of giant crayfish found in US

January 2011: Two aquatic biologists have proved that you don't have to travel to exotic locales to search for unusual new species. They discovered a distinctive species of crayfish in Tennessee and Alabama that is at least twice the size of its competitors. 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.

REMARKABLE DISCOVERY: The newly described crayfish; Barbicambarus simmonsi.

‘If you were an aquatic biologist and you had seen this thing, you would have recognized it as something really, really different and you would have saved it,' said Chris Taylor, the curator of crustaceans at the Illinois Natural History Survey at the University of Illinois and co-discoverer of the new crayfish species.

The researchers found their first specimen under one of the biggest rocks in the deepest part of a stream that has been a stomping ground for aquatic biologists for at least half a century. 

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.

It is something really, really different
‘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.

Schuster first learned of the crayfish in 2009 when a colleague forwarded photos from a man who had seen the animal in Shoal Creek, a stream in southern Tennessee that ultimately drains into the Tennessee River. Schuster immediately recognised it as a member of the genus Barbicambarus, and sent the photos to Taylor, his longtime collaborator. The researchers contacted a colleague in Tennessee, who told them that a scientist with the Tennessee Valley Authority, Jeffrey Simmons, had collected a crayfish that looked like the one in the photo near the same spot.

We were ready to give up, admit researchers
So, with two other biologists, Taylor and Schuster scoured Shoal Creek for more specimens. After two hours of turning over boulders and kicking up the sediment to flush the crayfish into their seine, the researchers had found nothing out of the ordinary.

‘We were ready to give up,' Schuster said. ‘And we saw this big flat boulder underneath a bridge and so we said, "OK. Let's flip this rock, just for the heck of it; this will be our last one." And that's where we got the first specimen.'

It was a big male, about twice the size of any other crayfish they had seen that day. And it had the characteristic bearded setae. The researchers found only two specimens that day, a very small haul for nearly three hours of work. The second specimen, a female, was under a large, flat boulder.

Back in the lab, Schuster quickly realised 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. ‘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 honour of the TVA scientist who had collected the first specimen.

The new species is described in a paper in the Proceedings of the Biological Society of Washington.