Biologists from the National University of Singapore have identified a new deep-water species of box crab.

The crab, called Calappa karenae, is known from the island of Guam and has an unusually broad carapace measuring about 9 cm in length and 17 cm in width.

“The new species differs from its congeners by its distinctive coloration and conspicuously wide carapace,” lead author Dr Peter Ng, and his colleague Dr Joelle Lai, said in a paper published in the journal Zootaxa. “It is one of the largest Calappa species known from the Indo-West Pacific.”

The discovery of Calappa karenae has a remarkable history. In 2000, Dr Gustav Paulay of Florida Museum of Natural History invited Dr Ng to work on the crab fauna of Guam. A photograph by Dr Roy Kropp of a bright red crab with broad carapace obtained from relatively deep water caught the author’s eye.

The specimen, however, could not be found even though it was known to have been deposited in the US Natural History Museum, Smithsonian Institution. Several visits to the museum failed to find this unusual specimen.

“In January 2011, during a workshop on xanthoid systematics hosted at the MSC, the authors, assisted by collection manager Karen Reed, looked through unidentified calappid material to check on a number of taxa and the elusive jar with two specimens, including the one photographed by Dr Kropp, was found. It proved to be a new species,” the authors said.

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Bibliographic information: Ng, P.K. L., Lai, J.C.Y. 2012. Calappa karenae, a new species of box crab from Guam (Crustacea: Decapoda: Brachyura: Calappidae). Zootaxa 3393: 57–65