Pune zoologists find 2 new species of freshwater crabs
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PUNE:
Local farmers know all about the small reddish crabs in the rice fields
of southern Odisha and the nearby streams, but the scientific community
remained unaware that these crustaceans in plain view during the
monsoon months are a distinct species, so far unrecorded.
City-based scientists Sameer Kumar Pati and R M Sharma have identified two new species of freshwater crabs -Oziotelphusa ganjamensis in southern Odisha and Travancoriana granulate in the southern Western Ghats.
Pati, who works for the Zoological Survey of India (ZSI), hails from Odisha and came upon the Oziotelphusa ganjamensis on one of his trips back home.
"On observing the crab closely, I realized that it was not similar to other rice-field crabs. I collected a few for study which revealed that this was a new species," Pati said. The classification of the organism as a new species was based on its distinct gonopods - a copulatory organ in crabs.
Pati and Sharma published their findings in the international journal Zootaxa. While they have described the species in detail in their paper, Pati believes further research is required. "I found the crabs in large numbers in paddy fields and nearby streams where farmers do not use any pesticides. However, I couldn't find any in areas with the same habitat where pesticides are used," he added.
P S Bhatnagar, scientist-in-charge of the western regional centre of ZSI said that the crabs appear to have adapted to the eco-system of the rice-fields where water is abundant and they can easily feed on insects and pests.
Using pesticides will disturb this natural harmony, possibly threatening their survival.
The second discovery - made at the Eravikulam National Park in Kerala - occurred when a ZSI team was conducting a survey in the area.
While collecting specimens from the Bhimnada peak within the national park, Pati chanced upon a crab that looked similar to others found in the low-lying areas, but unlike them, contained granules on its carapace. Careful examination of the collected specimen revealed other differences from the crabs found in the low-lying areas.
The crab appears to have adapted to the climatic conditions in the higher altitude of the peaks in the protected area where the temperature drops below freezing point in winter.
Eventually, Pati and Sharma were able to identify it as a distinct species, publishing their findings in the Zoosystematics and Evolution journal. "It is possible that the crab evolved as a distinct species because of the different environmental conditions at higher altitudes," Pati said. There are about a hundred known species of freshwater crabs in India.
Found only in small, lowland-forest ecosystems in the Palawan island group, most have purple shells, with claws and legs tipped red.
"It is known that crabs can discriminate colours. Therefore, it seems likely that the colouration has a signal function for the social behaviour, e.g. mating," Freitag told AFP by email on Saturday.
"This could explain why large males of various Insulamon species are more reddish compared to the generally violet females and immature males."
Scientists began extensive investigations of similar freshwater crabs in the area in the late 1980s, when one new species was found -- the Insulamon unicorn, Freitag said.
More field work 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 wrote in the latest edition of the National University of Singapore's Raffles Bulletin of Zoology.
The carapace of 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 called 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.
Reptiles, birds or mammals likely prey on the crabs, and it is possible people in remote areas also collect them for food, Freitag said.
However, the main threats are the ongoing forest clearing for farming, mining or home building, since this risks drying up their small habitats and causes water pollution, he said.
"Even if the habitats are not entirely destroyed, the smaller the remaining habitats, the higher the risk of extinction for a species," he said.
City-based scientists Sameer Kumar Pati and R M Sharma have identified two new species of freshwater crabs -Oziotelphusa ganjamensis in southern Odisha and Travancoriana granulate in the southern Western Ghats.
Pati, who works for the Zoological Survey of India (ZSI), hails from Odisha and came upon the Oziotelphusa ganjamensis on one of his trips back home.
"On observing the crab closely, I realized that it was not similar to other rice-field crabs. I collected a few for study which revealed that this was a new species," Pati said. The classification of the organism as a new species was based on its distinct gonopods - a copulatory organ in crabs.
Pati and Sharma published their findings in the international journal Zootaxa. While they have described the species in detail in their paper, Pati believes further research is required. "I found the crabs in large numbers in paddy fields and nearby streams where farmers do not use any pesticides. However, I couldn't find any in areas with the same habitat where pesticides are used," he added.
P S Bhatnagar, scientist-in-charge of the western regional centre of ZSI said that the crabs appear to have adapted to the eco-system of the rice-fields where water is abundant and they can easily feed on insects and pests.
Using pesticides will disturb this natural harmony, possibly threatening their survival.
The second discovery - made at the Eravikulam National Park in Kerala - occurred when a ZSI team was conducting a survey in the area.
While collecting specimens from the Bhimnada peak within the national park, Pati chanced upon a crab that looked similar to others found in the low-lying areas, but unlike them, contained granules on its carapace. Careful examination of the collected specimen revealed other differences from the crabs found in the low-lying areas.
The crab appears to have adapted to the climatic conditions in the higher altitude of the peaks in the protected area where the temperature drops below freezing point in winter.
Eventually, Pati and Sharma were able to identify it as a distinct species, publishing their findings in the Zoosystematics and Evolution journal. "It is possible that the crab evolved as a distinct species because of the different environmental conditions at higher altitudes," Pati said. There are about a hundred known species of freshwater crabs in India.
Four new crab species found
: This undated handout photo released by Hendrik Freitag, of
Germany's Senckenberg Museum of Zoology on April 21, 2012 shows one of
the four new species of freshwater crab found in remote areas of the
Palawan island group.
Image by: Hendrik Freitag / SMZ / AFP
Image by: Hendrik Freitag / SMZ / AFP
Four new species of freshwater crab, bright purple in colour, have been discovered in the biologically diverse but ecologically-threatened Philippines, the man who found them said Saturday.
The tiny crustaceans burrow under boulders and roots in streams, feeding on dead plants, fruits, carrion and small animals in the water at night, said Hendrik Freitag of Germany's Senckenberg Museum of Zoology.Found only in small, lowland-forest ecosystems in the Palawan island group, most have purple shells, with claws and legs tipped red.
"It is known that crabs can discriminate colours. Therefore, it seems likely that the colouration has a signal function for the social behaviour, e.g. mating," Freitag told AFP by email on Saturday.
"This could explain why large males of various Insulamon species are more reddish compared to the generally violet females and immature males."
Scientists began extensive investigations of similar freshwater crabs in the area in the late 1980s, when one new species was found -- the Insulamon unicorn, Freitag said.
More field work 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 wrote in the latest edition of the National University of Singapore's Raffles Bulletin of Zoology.
The carapace of 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 called 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.
Reptiles, birds or mammals likely prey on the crabs, and it is possible people in remote areas also collect them for food, Freitag said.
However, the main threats are the ongoing forest clearing for farming, mining or home building, since this risks drying up their small habitats and causes water pollution, he said.
"Even if the habitats are not entirely destroyed, the smaller the remaining habitats, the higher the risk of extinction for a species," he said.
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