San José, Costa Rica, since 1956

New crab species discovered in Costa Rica

A group of Costa Rican biologists have discovered a new species of river crab, and experts believe the crab only exists in Costa Rica’s Southern Zone.

The discovery of the species, the Allacanthos yawi, was published in the September 2010 edition of the zoological taxonomist journal, Zootaxa.

The new species was found 1,000 meters above sea level along riverbanks in the Río Volcán, which is located at the basin of the Río Grande de Térraba, and along offshoots of the Río Cañas.

The male crab measures 2.8 centimeters in width and 1.6 centimeters in length, and the female reaches up to 2.7 centimeters in width. 

The crabs are distinguished by olive and green colors on their back side and yellow and turquoise shades on their belly.

In Costa Rica, 18 species of river crabs exist, representing six different genera, including the most recent discovery.

For Ingo Wehrtmann, a researcher from the University of Costa Rica’s Zoology Museum and who helped identify the crustacean, the discovery is a rare treat.

“To discover a new species of river crab for the country isn’t something that happens often,” he said.

The crab was originally found in 2009 by Luis Rólier Lara Hernández, a technical assistant conducting biological research near Buenos Aires in the Southern Zone for the Costa Rican Electricity Institute’s proposed El Diquís hydroelectric plant.

The dam, should it be built, would be the largest hydroelectric project in Central America, potentially producing 630 megawatts. In spite of the project, Wehrtmann called for the protection of the animal and its habitat. He said that the greatest threat to the crab is the expansion of pineapple farms near Buenos Aires.

“This discovery should motivate us to protect rivers, streams and habitats that shelter a large number of aquatic insect species, fish and now crabs, which are only found in Costa Rica and are threatened by pollution,” he said.

The description of the crab for Zootaxa was completed by Brazilian crab expert Célio Magalhaes and the name was chosen with help from Costa Rican archeologist Melania Pérez.

The name yawi means “river crab that lives under rocks” in Cabécar, an indigenous language from the region.

The research and identification of the Allacanthos yawi was funded by Brazil’s National Board of Scientific and Technological Development and by Costa Rica’s National Board of Scientific and Technological Research.

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