The reddish-violet species of the Insulamon crab genus was found on Palawan, a biodiversity hot spot where 50 percent of the species are found nowhere else in the world, wired.co.uk reported Monday.
The crab species on the island are unable to spread elsewhere, as they skip the larval stage in seawater and depend on freshwater at all stages of their development, keeping them contained in Palawan's inland waters, researchers said.
The colors of the purple crab, Insulamon palawense, likely serve as a signal function for some social behavior such as mating, researchers said, since it's known crabs can discriminate colors.
The discovery of the crabs comes as Palawan's biodiversity is coming under threat from several mining projects and as parts of the forest are being cleared for farms and homes, scientists said.
"The smaller the remaining natural habitat the greater is the risk to endemic fauna and flora," said Hendrik Freitag of Germany's Senckenberg Museum of Zoology.
"Even minor environmental changes can lead to extinctions. It is all the more important to do research in this region and show that the biodiversity of these islands is unique and worth protecting."