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Colourful river crabs: newly discovered and already threatened

21 March 2012 Senckenberg Research Institute and Natural History Museum

Mining project puts recently identified crab species at risk

Scientists at the Senckenberg Research Institute in Dresden and De La Salle University in Manila have discovered four new species of the colourful Insulamon freshwater crab as part of their Aqua Palawana research programme. But various mining projects on the island of Palawan pose a huge threat to these creatures. The relevant study was recently published in the scientific journal Raffles Bulletin of Zoology.

The Philippine island of Palawan is something special. Located between the Sundaic and Philippine region it 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.

“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”, says Dr Hendrik Freitag from 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 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”, says Freitag.

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. 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”, says Freitag and adds, “that’s why our next step is to investigate Palawan’s species-rich freshwater prawns”.

As an associate professor at the Ateneo de Manila University Freitag increasingly gets local students involved in bio-systematic research, in order to create awareness of this unique habitat.

Participants cooperating in the Aqua Palawana research project in addition to Senckenberg and the Phyllodrom Leipzig are the Ateneo de Manila University, Western Philippines University, De La Salle University Manila and the Philippine National Museum, as well as the Vienna Natural History Museum and the National University of Singapore.

Attached files

  • A particularly colourful new species: Insulamon palawanense


  • IInsulamon magnum – one of the freshwater crabs recently discovered on Palawan


  • The recently discovered Insulamon johannchristiani species also exists only on Palawan


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