Tridacna ningaloo officially described as a new species of giant clam

Tridacna ningaloo is the newest species of bivalve we can welcome into the growing family of giant clams. Earlier this year scientific research into the genetic makeup of Australian giant clams revealed that a cryptic species was lurking among the Tridacna around Ningaloo in western Australia, and now the species has been officially described.

From a distance the newly described Tridacna ningaloo has an appearance closest to the most widespread species, T. maxima but genetically it is more closely related to T. squamosa. T. ningaloo is differentiated from other species in the genus Tridacna by having an asymmetrical shell which is highly elongate, and it usually has one less shell ‘rib’ or undulation than specimens of Tridacna maxima from the region.

The mantle of T. ningaloo bears some similarities with both squamosa and maxima clam with eclectic colors that can be mottled, swirled or dashed but often appearing somewaht darker. The biggest noticeable difference about the ningaloo giant clam is a marked greater abundance of papillae (protrusions) on its mantle giving it a somewhat bumpy and less smooth appearance than its congeners.

Those bumps on the mantle are diagnostic from an aquarist’s point of view, given that the type locality of the clam is also known and it is with these details that we conclude that T. ningaloo has been exported for the aquarium market before. Even before the genetic analysis of these western australian “maxima” clams was known, aquarium experts such as Julian Sprung and Kevin Kohen had already begun to suspect that the maxima clams with the bumpy surface from Western Australia were possibly a new species.

Australian reefers have long considered some of the clams from western australia, and particularly Ningaloo Reef as being a distinct species and home clam farmer extraordinaire Acro Al recently reported that he has already succeeded in breeding and raising this species in captivity. The difficulty in identifying this species in the field poses some challenges to conservation for this species in the future.

While the species is identified and described from specimens clustered around Ningaloo Reef, Western Australia, there is some evidence to support that this species could be distributed in small densities all the way to the Solomon Islands. The newest species of giant clam Tridacna ningaloo is described volume 34 of Molluscan Research by Shane Penny and RIchard Willan.