Eye-popping purple crabs discovered in the Philippines

Jeremy Hance
April 23, 2012

New species of purple crab: Insulamon palawanense. Photo by: Hendrik Freitag.
New species of purple crab: Insulamon palawanense. Photo by: Hendrik Freitag.

Scientists have discovered four new species of brilliantly-colored freshwater crabs on the Philippine island of Palawan. Described in the Raffles Bulletin of Zoology, the new species expands the genus, Insulamon, from one known crab species to five. Although its ecosystems are threatened by widespread mining and deforestation, the Philippines is a mega-diverse country, meaning that it belongs to a select group of 17 countries that contain the bulk of the world's species.

Found in streams, the primarily nocturnal crabs feed on plants as well as small animals. The largest of the four new species is still quite small, its carapace spanning 5.3 centimeters, while the smallest carapace's measures just 2.5 centimeters. The researchers theorize that the bright colors evolved for mating behavior.

The discovery of the new crab species follows two other recent biodiversity announcements in the Philippines. Two new frogs were discovered in Leyte Island in a biological survey last year. Meanwhile, the Dinagat bushy-tailed cloud rat (Crateromys australis) was rediscovered earlier this year after not being recorded for nearly forty years.

Palawan is home to a number of imperiled species only found in the Philippines, including the Palawan peacock-pheasant (Polyplectron napoleonis), listed as Vulnerable by the IUCN Red List; the Philippine mouse-deer (Tragulus nigricans), Endangered; the Philippine pangolin (Manis culionensis), Near Threatened; the Palawan bearded pig (Sus ahoenobarbus), Vulnerable; and the Palawan Hornbill (Anthracoceros marchei), Vulnerable.

Palawan Island retains around half of its forest cover, but most of this in mountainous regions. The island's lowland forests are imperiled by deforestation and mining, including widespread illegal mining. The Philippines remaining primary forests are largely found on Palawan.

CITATION: Hendrik Freitag. Revision of the genus Insulamon NG and Takeda, 1992 (Crustacea: Decapoda: Potamidae) with description of four new species. The Raffles Bulletin of Zoology. 2012 60 (1): 37-55.

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Jeremy Hance
mongabay.com (April 23, 2012).

Eye-popping purple crabs discovered in the Philippines.