January 22, 2009—This fish out of water is a newly identified species from a remote region in Venezuela.
The catfish handily inches along rocks using its highly flexible pelvic fins (bottom, the two leg-like appendages) and wide mouth as grasping tools. Such climbing ken may be crucial for the fish, which live in strong, high-flow streams.
An anthropologist first collected the fish in the state of Amazonas about two decades ago, but the odd sample brought to Caracas's Instituo de Zoologíca looked "like it was run over by a truck," American Museum of Natural History ichthyologist Scott Schaefer said in a statement.
Intrigued, Schaefer and colleagues eventually pinpointed the source of the fish—a tributary of the Orinoco River—and literally picked 84 specimens off of rocks.
New analysis of the samples, published in the journal American Museum Novitates, confirmed that the new species, dubbed Lithogenes wahari, belongs to a group of fish that span two families.
Bony plates on its head and tail (top) link the creature to Loricariidae, a family of armored catfishes.
But its specialized pelvic fins—which move backward and forward independently—are seen only in Astroblepidae, a family of climbing catfish found in the Andes.
(Related story: "Fish Lives in Logs, Breathing Air, for Months at a Time" [November 6, 2007].)
The combination of features suggests that common ancestors to both fish families lived in upland streams of the Amazon and Orinoco Rivers, which currently house most of the groups' members.
"We see new fish species all the time," Schaefer said, "but when you also get new information about the biological history of a group, it's the most fun."