A team of scientists from the Senckenberg Research Institute in Dresden and De La Salle University in Manila has discovered four new species of the freshwater crab on the Philippine island of Palawan.

A paper, published in the journal Raffles Bulletin of Zoology, describes four new species of the colorful Insulamon freshwater crab, called Insulamon palawanense, I. magnum, I. johannchristiani and I. porculum.

“In the Aqua Palawana research programme I am head of, we have been investigating the biodiversity of Palawan’s inland waters for over 10 years”, said Dr. Hendrik Freitag of the Senckenberg Natural History Collections in Dresden. “This also included taking a closer look at the Insulamon crabs and we discovered four new species in the process.”

The Philippine island of Palawan, located between the Sundaic and Philippine region, combines two of the world’s most important biodiversity hotspots. Its bio-geographical special status is also reflected in its fauna and flora. Around 50 per cent of the species living on Palawan are defined as endemic, as they are exclusively native to the island.

The reddish violet species of the Insulamon crab genus are the only varieties that are endemic to only one or a few islands. The sea means these creatures are unable to spread elsewhere, as they skip the larval stage in seawater and depend on freshwater at all stages of their development. Having been completely separated from their relatives, they have developed their own separate species and genera over tens of thousands of years.

“We have proved that the only previously known type of Insulamon is restricted to the Calamian group of islands to the north of Palawan. The four newly discovered species live exclusively on the actual island of Palawan and make it a unique habitat”, Dr. Freitag explained.

But this unique biodiversity is under threat. Several mining projects are to be conducted despite massive protests by people from all walks of life and against the resistance of indigenous peoples.

“The smaller the remaining natural habitat the greater is the risk to endemic fauna and flora,” Dr. Freitag said. “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. That’s why our next step is to investigate Palawan’s species-rich freshwater prawns”.