ARKHANGELSK, June 24. /TASS/. Scientists of the Federal Research Center for Integrated Arctic Studies of the Russian Academy of Sciences' Urals Branch (Arkhangelsk) discovered two new genera of freshwater mollusks in India. The biologists named one of them Assamnaia, that is, a naiad from the state of Assam, and the second genus was named Pseudoscabies, the Center's Director, the Russian Academy of Sciences Corresponding Member Ivan Bolotov told TASS.
"It is a very interesting discovery, and the region, where this work was done, is a special place. It is the state of Assam in northeastern India, few people have worked there or conducted research. These mollusks, collected alive, formerly have been seen in the form of dry shells, collected in the late 19th century. We have managed to find viable populations of both of these mollusks, and they have turned out to be very specific from a genetic point of view, and we have described them as two new genera. This is a very significant discovery in freshwater malacology," the scientist said.
Russian specialists have supervised remotely morphological and genetic studies performed by Indian scientists. India conducted fundamental research in molluscan taxonomy during the years of direct subordination to the British Empire (until the middle of the 20th century). The information was very outdated, and relied only on morphological data. The work in partnership with German scientists in the 2010s did not bring tangible results, thus Indian specialists turned to a group of Russian malacologists.
The significant interest in the study of freshwater mollusks in India can be explained by the fact that they are highly sensitive bio indicators of aquatic environment. The degree of rivers' pollution and salinity is determined by the species composition and conditions. Besides, bivalves are eatable.
The Indian legislation severely restricts export of biological materials, which hindered the cooperation. Thus, Indian biologists collected samples and processed them according to protocols provided by the Arctic Center scientists. Genetic tests were performed at the Rajiv Gandhi Center for Biotechnology (RGCB), while Russian researchers conducted taxonomy.
The new genera mollusks are quite big, the size of their shells is 5-6 cm. The Assamese has a thin and fragile shell, while genetic naiads from Assam are close to mollusks from the genus Parreysia that have very massive and hard shells. Pseudoscabies are superficially similar to the Scabies genus mollusks, which live in Thailand and Laos in the Mekong River basin. Their shells have a specific zigzag pattern. However, the genetics results have shown that is a special Indian species and genus that bears a resemblance to scabies, perhaps due to the habitat peculiarities. Both populations are small.
Indian mollusks reviewed
The international team has found there are nine species of naiads in Assam, and only two of them are found in other regions of India. Three genera, including seven species, are endemic to the Brahmaputra basin. This allows a supposition that the Brahmaputra was isolated for a long time from other big bodies of water in the Indian subcontinent, including the Ganges River. Nowadays, it is the Ganges' tributary. "The Brahmaputra River basin is a very interesting area," he continued. "We haven't imagined, but it turned out that it is an ancient center of endemism that has developed separately. These mollusks have a great genetic distance from related species in other regions of the Indian subcontinent."
The Brahmaputra's another endemic genus is the Balwantia genus. They have an elongated shell shape, they live in burrows that they dig in the hard clay of river banks. During the study, Russian specialists created a reference library of genetic sequences of freshwater mollusks in India, and Indian scientists now can correctly identify naiad species by molecular data.
The Center will continue to study India's freshwater mollusks, and has plans to study mollusks in reservoirs of Sri Lanka, Bangladesh and Pakistan, he added.
Continental drift
This study is part of a global paleo reconstruction project, which demonstrates that the ancestors of mollusks that live in Indian reservoirs drifted millions of years ago along with the Indian Plate, which had separated from the ancient continent of Gondwana, through the Tethys Ocean. "A significant group of mollusks that now live in Africa have descended from the mollusks that live in India, and they have a common ancestor. The Brahmaputra basin studies have confirmed the results, obtained earlier in the study of the Ganges and other major Indian. This is unequivocal. We can see this is the same subfamily, that is, the same ancient group that drifted from Africa to Asia on India, like on a ferry," the scientist said. Naiads of India and some other South Asian countries are genetically close to Africa's malacofauna representatives, he added.
Some 335 - 175 million years ago, there was one supercontinent on the Earth - Pangaea. Later, it split into two supercontinents - Gondwana and Laurasia. Gondwana included Africa, South America, Australia and a number of other tectonic plates, while Laurasia included North America and Eurasia. According to modern ideas, Hindustan was part of Gondwana, and was adjacent to Africa. "By accumulating the data, we assume, we will be able to create a supermodel, to calculate data using supercomputers, to look at the Globe's plate tectonics from the point of view of biological evolution," the scientist said in conclusion.