New giant clam species discovered

In a surprising find, Australian researchers have discovered a vivid new species of giant clam on reefs in the Solomon Islands and at Ningaloo in Western Australia.

Giant clams, from the genus Tridacna, are classic coral reef animals found in the Indian and Pacific Oceans. Easily recognisable by their massive shells and vibrantly coloured mantle tissue, their populations have been depleted by extensive harvesting by humans.

“DNA sequences strongly suggest that a distinct and unnamed species of giant clam has been hiding literally in plain sight, looking almost the same as the relatively common Tridacna maxima,” said postgraduate biological sciences student at the University of Queensland Jude Keyse.

“Giant clams can grow up to 230 kilograms and are some of the most recognisable animals on coral reefs, coming in a spectrum of vibrant colours including blues, greens, browns and yellow hues.”

Charles Darwin University postgraduate student Shane Penny, who collaborated in the work, said identifying a new species within a well-known group such as giant clams was a unique opportunity.

“To correctly describe the new species now becomes critical as the effects of getting it wrong can be profound for fisheries, ecology and conservation," he said.

Giant clams are beloved by divers and snorkellers but also prized as a source of meat and shells.

Over-consumption by humans has depleted giant clam populations in many areas and most giant clam species are on the International Union for Conservation of Nature Red List of Threatened Species.

Keyse said the discovery of a new species had implications for management of giant clams.

“What we thought was one breeding group has turned out to be two, making each species even less abundant than previously thought,” she said.

These results have been published in the open access journal PLoS One.