Four New Species of Freshwater Crab Discovered in the Philippines

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Four New Species of Freshwater Crab Discovered

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.

New species of the colorful freshwater crab Insulamon palawanense (Hendrik Freitag)

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.

Insulamon magnum (Hendrik Freitag)

“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.

Insulamon johannchristiani (Hendrik Freitag)

“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”.

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New purple crab species found in Philippines

Saturday, April 21, 2012 – 17:04
crabA photograph of the crab taken from the Senckenberg museum

MANILA: Four new species of freshwater crab, bright purple in colour, have been discovered in the biologically diverse Philippines, according to a scientific paper.

The tiny crustaceans were found in streams in remote areas of the Palawan island group, according to a team led by Hendrik Freitag, of Germany’s Senckenberg Museum of Zoology.

“They are semi-aquatic and hide in burrows at the stream bank, which are usually found under boulders and roots,” said his paper published in the latest edition of the National University of Singapore’s Raffles Bulletin of Zoology.

Their eggs hatch directly into juvenile crabs, and the creatures emerge at night to forage under water, Freitag added.

Photographs of the adult crabs published on the website of Dresden-based Senckenberg museum showed them with a purple carapace, and with claws and legs tipped red.

Scientists began extensive investigations of similar freshwater crabs in the area in the late 1980s, with one new species being found – the Insulamon unicorn – Freitag’s paper said.

More field work in the noughties led Freitag to conclude there were four other unique species.

“Based on available new material, a total of five species are recognised… four of which are new to science,” Freitag said.

The biggest, Insulamon magnum, is just 53 millimetres by 41.8 millimetres while the smallest, Insulamon porculum, measures 33.1 by 25.1 millimetres.

The two other new species were Insulamon palawense and Insulamon johannchristiani.

The four slightly differ from the first find, and from each other, in the shapes of their body shells, legs, and sex organs.

US-based Conservation International lists the Philippines as one of 17 countries that harbours most of Earth’s plant and animal life.

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