Dark softshell turtle
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Dark softshell turtle ( Nilssonia nigricans ) |
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| Nilssonia nigricans | ||||||||||||
| ( Anderson , 1875) |
The dark softshell turtle ( Nilssonia nigricans ), also known as the temple softshell turtle , is a rare species of turtle belonging to the Indian softshell turtle . It is one of the large breed softshell turtles , the carapace length of Indian softshell turtle can reach. It has long been considered extinct in the wild, with a single occurrence in a pond belonging to a shrine in Chittagong in southeastern Bangladesh . This population amounted to three hundred individuals in 1986 and grew to more than 500 animals by 2015. Since the beginning of the 21st century, further postures in temples, but also several natural populations have been discovered in the Indian state of Assam . As a result, the dark softshell turtle is no longer considered to be extinct in nature, but rather viewed as acutely critically endangered. The flourishing trade in turtles for consumption or keeping as pets and the destruction of habitats pose great threats to the species, despite the ban.
Appearance
The dark softshell turtle has an oval and flat shell ( carapace ) with a length of up to 91 centimeters. The carapace is from olive to gray in color in different shades and has a clearly visible network drawing and a narrow yellow border. Its surface has a rather rough surface structure. The massive head also has a net markings, but no yellow or orange spots behind the eyes and across the muzzle. The plastron is white to light gray and has four large calluses. Juvenile specimens have an olive-green carapace, which has a distinct dark net markings and four to six olive-green-orange-black-brown eye spots with small red dots. The yellow edge of the carapace is more clearly visible in comparison to adult specimens.
Two color morphs are reported in the older literature . A color morph has a copper-colored, shiny back armor with black spots and dark spots with increasing age. The belly armor is white, the top of the head and neck are gray. The temple and upper lip are spotted white. The second color morph therefore has an olive-green armor on the back, on which there are also dark spots. In this morph, the head on the upper side is gray-olive, while the snout, neck and the area above the eyes are dark yellow. In more recent literature, the distinction between color morphs is no longer taken up. It is possibly based on historical descriptions, which can also be based on incorrect identifications.
The Scottish zoologist John Anderson described the species in 1875 as follows: The back armor is olive green with black and rust brown spots. The head, neck, and outsides of the limbs are almost black, the front two thirds of the upper lip are white, and there is a white spot above the ear. The area between the neck and forelegs is whitish and there are some white spots on the edge of the shell. The head has a net-like pattern and there are black stripes in front of and above the eyes, which can hardly be seen on the dark base color. The undersides of the head and neck are almost black, on the plastron and tail there are densely arranged dark purple spots. The claws are yellow.
Anderson's compatriot Nelson Annandale , on the other hand, gave the following description forty years later: copper-colored carapace with dark marbling. Head and limbs dark clay color, but always covered with mud. The top and sides of the head are bright blue-green with a yellow markings around the eyes and nostrils, the rest with a strong network markings in black or dark green. Very old turtles have black heads with green dot markings that fade with age.
From today's perspective, it seems likely that changes in color are age-related, with the olive-green carapace of juvenile animals changing from the black-brown of subadults to a very dark gray in adult specimens, which brightens again in very old animals.
The sexual dimorphism is only weak, males have a longer carapace and a longer and thicker tail. The dark softshell turtle differs from the very similar peacock-eye softshell turtle by the rougher surface of the carapace and the larger head with a much less pronounced net markings and the missing yellow or orange spots behind the eyes and above the snout.
Way of life
Dark softshell turtles are diurnal, but live in hiding and are only seen occasionally sunbathing on sandbanks in winter. Their habitats are in the rivers of their range, natural occurrences in stagnant waters are not known. Nothing is known about their diet in nature either. Other species of the genus lurk buried in the mud for prey and feed mainly on fish. A clutch in nature contains six to 38 spherical eggs. Compared to other turtle species, the hatching rate is extremely low at only six percent.
The temple softshell turtles kept in the pond of the Bistāmī shrine in Chittagong show behavior that is adapted to the restrictions of the habitat. They spend the day mostly buried in the mud of the pond. During the night they go to a hill directly next to the pond, which is also used to lay eggs from mid-February to mid-March in rainy weather. The hill has an area of about 300 square meters, the soil is sandy to sandy and loamy with a pH of 7.5 and a humidity of 35.8 percent.
In the case of the temple's turtle population, it is noticeable that the egg-laying female turtles, with an average carapace length of 48.2 centimeters and a weight of 12.6 kilograms, are significantly smaller than those females who do not lay eggs. They have an average carapace length of 63.5 centimeters and a weight of 27.6 kilograms. A female ready to lay her eggs leaves the pond in the late afternoon and goes to the hill. After 25 to sixty minutes of looking for a suitable place to lay eggs, within another ten to twenty minutes it digs a nesting pit with a diameter and a depth of 15 to 20 centimeters. Then, within five to fifteen minutes, it lays 10 to 38 round, white eggs that are 3.2 to 3.6 centimeters in diameter and 20 to 29 grams in weight. The size of the clutch depends on the size of the turtle. It takes five to ten minutes to fill the nest pit, then the turtle goes back into the pond.
The time it takes for young animals to hatch from the eggs is between 73 and 108 days. The time of hatching coincides with the onset of the monsoons . The rain then softened the ground. Newly hatched young animals weigh between 14 and 19 grams, with a carapace of 4.5 to 5.1 centimeters. Although the soil appears suitable and eggs are laid annually, the hatching rate is very low and the mortality of the young turtles is high. In a 1985 study, around 40 percent of eggs in nests hatched turtles, compared to 70 percent in a hatchery. The number of eggs deposited each year fluctuates widely and between 2010 and 2015 was between 142 and 567 eggs, of which 18 to 101 hatched. Although the Bistāmī shrine is fenced in, the clutches are lost by predators , of whom thick-billed crows , domestic dogs and domestic cats have been seen robbing eggs. Golden jackals , reed cats , civets and mongooses are also seen as a threat. Occasionally, clutches are destroyed by humans.
At the beginning of the 20th century, the age of the oldest turtles in the shrine was estimated to be 150 years, based on surveys of local residents. According to current information from the shrine administration, the oldest turtles can be 150 to 200 years old.
distribution
The type location is a pond that belongs to the shrine of Bāyazīd Bistāmī ( 22 ° 23 ′ 20 ″ N , 91 ° 48 ′ 36 ″ E ). It is located in Upazila Hathazari, in the immediate vicinity of the city of Chittagong . It was not until the 21st century that a number of other postures in temples in the Indian state of Assam became known; these animals had previously been identified as other species of the genus. In addition , natural populations of the dark softshell turtle have been identified in several places in the Brahmaputra catchment area , also in Assam. From Bangladesh only two records of the dark softshell turtle in nature are known.
With DNA barcoding of environmental DNA , the presence of the dark softshell turtle in a body of water has been able to be detected for a few years now, even without sightings and sampling of captured animals. Evidence of further populations is expected in the near future.
Natural populations in northeast India and Bangladesh
Natural populations of the dark softshell turtle occur in various locations in the Brahmaputra catchment in the Indian state of Assam . The Kaziranga National Park ( 26 ° 40 ′ 0 ″ N , 93 ° 21 ′ 0 ″ E ) is home to the first population of the dark softshell turtle to be found within a nature reserve. Outside the national parks, the species is extremely rare and threatened with habitat destruction and hunting. Evidence of the species can also be found in Manas National Park ( 26 ° 43 ′ 0 ″ N , 90 ° 56 ′ 0 ″ E ), Pakke Wildlife Sanctuary ( 27 ° 5 ′ 0 ″ N , 92 ° 51 ′ 30 ″ E ), Namdapha- National Park ( 27 ° 38 '59.4 " N , 96 ° 6' 37.1" O ), orang-National Park ( 26 ° 33 '24.5 " N , 92 ° 19' 40.4" O ) and Nameri- National Park ( 27 ° 0 ′ 36 ″ N , 92 ° 47 ′ 24 ″ E ). Further details on these populations are not known.
As part of a phylogenetic investigation of specimens of the five species of Indian softshell turtle, two specimens from Bangladesh were identified as dark softshell turtles. It was the carapace of a slain turtle from the Upazila Srimangal ( 24 ° 18 ′ 34.6 ″ N , 91 ° 43 ′ 31.8 ″ E ) in the Moulvibazar District of the Sylhet Division in the extreme northeast of Bangladesh. A living Dark soft-shelled turtle with unusually bright color was in a trench in the Upazila Manikchhari ( 22 ° 50 '4.9 " N , 91 ° 50' 10" O ) in the district Khagrachari District of Division Chittagong found.
Temple softshell turtles in Northeast India
- Bhairavi Temple in Guwahati
In the Bhairavi Temple or Kamakhya Temple ( 26 ° 9 ′ 59.1 ″ N , 91 ° 42 ′ 19.8 ″ E ) as part of a temple complex around the Kamakhya Temple in Guwahati , the largest city of Assam, live next to temple Softshell turtles Ganges softshell turtles ( Nilssonia gangetica ) and peacock-eye softshell turtles ( Nilssonia hurum ). The pond of the temple has an area of 0.33 hectares, it is at an altitude of 159 meters above sea level.
- Hayagriva Madhava Temple in the Hajo Pilgrimage Center
In the Hayagriva Madhava Temple ( 26 ° 14 ′ 38.8 ″ N , 91 ° 31 ′ 35 ″ E ) in the Hajo pilgrimage center, about 30 kilometers west of Guwahati, Ganges softshell turtles ( Nilssonia gangetica ) live alongside the temple softshell turtles. and peacock softshell turtles ( Nilssonia hurum ). Other species kept here are the Indian softshell turtle ( Lissemys punctata ), the three- keeled ray turtle ( Geoclemys hamiltonii ), the Assam roof turtle ( Pangshura sylhetensis ), the Indian roof turtle ( Pangshura tecta ) and the Indian tent turtle ( Pangshura tentoria ). The pond of the temple has an area of 1.33 hectares, it is at a height of 85 meters, according to other sources, 49 meters above sea level.
Until 2007 the pond was surrounded by a plantation of coconut trees. After clearing them, the unpaved banks of the pond were provided with concrete edges. According to local residents, the number of turtles kept was more than 1000. Various fish species were associated with them, such as Cirrhinus mrigala , Labeo rohita and Labeo calbasu . The water quality was poor, with heavy algal blooms and the lack of natural vegetation. The turtles were fed by visitors with food biscuits, which are sold by the temple, and also with food they had brought with them. Despite clear indications for the visitors, the plastic packaging of the food was often thrown into the water of the pond. According to the temple, clutches of turtles were often found a few years ago, but their number has greatly decreased after the banks were fortified.
In 2007 and 2008, an increased mortality rate among turtles was found in the pond, but only corpses largely freed from soft tissues were found, which did not allow the cause of death to be determined. During the investigation of lebed turtles caught, a strong infestation with turtle leeches of the genus Ozobranchus was found; the parasites were not identified more closely. As urgently necessary measures to save the population, the reduction of the stocking density, species-appropriate feeding including the introduction of forage plants, the renaturation of the bank areas with suitable breeding places and the creation of areas for sunbathing were suggested.
- Nagshankar Temple in Biswanath
In the Nagshankar Temple ( 26 ° 43 ′ 29.3 ″ N , 92 ° 59 ′ 39.8 ″ E ) the presence of the temple softshell turtle was detected for the first time in 2017 with the help of DNA barcoding from environmental DNA . According to its own information, this temple holds about 1000 turtles of various species, which come from believers, in its pond with an area of 0.4675 hectares. The pond is overpopulated due to the constant influx of new turtles and there is fierce competition for food. For religious reasons, the animals are often given biscuits, fruit and slices of bread. The overpopulation of the water and the inadequate feeding result in poor water quality, and there is a lack of places to sunbathe in order to keep them appropriately.
Dozens of turtles of numerous different species are brought by believers every year as a gift to the gods and given to the temple or exposed there. This leads to the socialization of species that are geographically or ecologically separated from one another in the wild. Many of the turtles are heavily infected with skin fungus, which makes it even more difficult to identify them in the cloudy water.
- Postures in North Indian temples without detailed information
- Sarupeta: pond of a temple ( 26 ° 49 ′ 0 ″ N , 91 ° 7 ′ 0 ″ E ).
- Tripura Sundari Temple ( 23 ° 53 ′ 0 ″ N , 91 ° 48 ′ 0 ″ E ) in Udaipur in the northeast Indian state of Tripura .
- Swaneswar Temple ( 26 ° 29 ′ 20.4 ″ N , 89 ° 31 ′ 37.2 ″ E ) in Alipurduar, West Bengal .
Temple softshell turtles in Chittagong (Bangladesh)
Locations in Bangladesh and neighboring India
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The captive population lives in a pond belonging to the shrine of Bāyazīd Bistāmī in Chittagong . Bāyazīd Bistāmī was an Islamic mystic of Sufism . Contrary to popular belief, which regards the shrine in Chittagong as Bistāmī's tomb, the tomb is actually in Bastam in the Iranian province of Semnan . Bistāmī has probably never been to Chittagong. In addition to an old mosque on a hill about 50 meters high, the facility includes a 94.64 × 61.27 meter rectangular pond (0.58 hectares) at the foot of the hill. The pond was probably created and repeatedly expanded in the 17th century. The pond is nine to ten meters deep in places, according to other information, the water depth varies between two and a half meters in winter and five meters during the monsoon. The banks are concreted. A staircase leads to the bank on either side. The visitors and pilgrims mainly use the stairs on the west side. During the three winter months the average temperature of the water drops to 10 to 14 ° C, in summer it rises to 32 ° C. Until the 1980s there was a second occurrence in a moat, but it was drained.
The origin of the turtles is unclear. As early as 1912 and 1914, the Scottish herpetologist Nelson Annandale reported that the temple tortoises were so tame that they came to feed on call. The temple's turtles have great spiritual significance. The turtle pilgrimage is believed to have healing properties, and the consumption of mud from the turtles' backs is believed to enable sterile women to conceive. There is also a widespread belief that the temple softshell turtles are the descendants of evil spirits who have drawn the wrath of the Almighty and have been turned into turtles as punishment. Nevertheless, they are considered sacred and, according to the temples, do not belong in the wild. The shrine generally does not release turtles and hinders research into the population. This has prevented reintroduction and populations outside the shrine to this day. Superstition may also be the reason why there was a poison attack on the pond, resulting in massive fish deaths. The shrine employs 31 people with the care of the turtles and the care of the pond and the adjacent breeding area. Fishing is prohibited in the pond, so a large number of fish live in the water.
The population was about 320 in 1986, of which 54 percent were adult males, 36 protents were adult females, and 10 percent were juveniles. In 1998 the population was estimated at 400 specimens. According to a census published in 2018, there were 467 individuals, which is a slight increase since 2014. When each turtle is stocked with 500 animals, the shrine has a water area of less than 12 square meters, plus around 0.6 square meters of land per animal. The population, which has increased in recent years, means that there is less and less space available for the individual animals. In addition, the living space lacks a number of important elements that are indispensable for species-appropriate housing. The turtles can only use the edge of the pond as a place to sunbathe and thus to regulate the body temperature, since the possible stay in the breeding area during the day is not accepted because of the great distance to the pond's retreat. There are only a few shady trees around the pond, making it difficult to retreat from the blazing sun. After all, there is a complete lack of suitable hiding spots. The banks of the pond are polluted, but the pond itself is clean.
The young turtles eat daily, the older ones get by with three to four feedings a week. The turtles receive 1 to 1.5 kilograms of food each week from visitors and employees of the shrine, which consists of bread, rice and fruit. Several stands in the vicinity offer shrimp, fish, bread, rice, tea leaves and bananas. Fish or their carcasses and underwater plants are also consumed. Overfeeding can affect fertility and lead to other health disorders. In addition, the large number of visitors is a permanent disruption that can also have negative effects. The area of the shrine is located away from the residential developments, so that there is no impairment by residents and at least the possibility of expanding the area is available.
In 2003 the shrine administration carried out an extensive renovation of the pond. Most of the water has been pumped out, the mud has been removed from the bottom and the walls and stairs around the pond have been renewed. In 2006 the water in the pond was poisoned by strangers. All fish died, the turtles could be temporarily moved to a safe place by the shrine administration. Over a period of two months, the water was pumped out and replaced with fresh water. When the pond was ready for use again, the turtles were brought back and security increased.
Hazard and protection
The dark softshell turtle has long been considered one of the rarest turtles in the world. It was considered extinct in nature by the IUCN and was only known from the population in the Bistāmī Shrine in Chittagong. The wild animals are often confused with other species and are threatened by the destruction of their habitats. In addition, the dark softshell turtle is particularly threatened by the continued trapping and trade, despite prohibitions and drastic penalties, as well as by the collection of the clutch. Further threats exist due to the small size of the populations and the small populated areas, disease outbreaks and comparatively minor interventions in the natural balance can quickly endanger entire populations.
The protection of their breeding areas and measures against poaching are urgently needed. The populations in the temples can provide valuable assistance in captive breeding.
In its Red Lists of 1996 and 2000, the IUCN designated the dark soft shell turtle as critically endangered ( CR ). The last formal assessment of the endangerment by the IUCN led to the classification as extinct in nature ( EW - Extinct in the Wild ) in 2002 . Since then, no new assessment has taken place. The Turtle Conservation Fund (TCF) and other conservation organizations, which also use the IUCN-developed scheme for assessing the risk of extinction, have classified the dark softshell turtle as critically endangered ( CR ).
The dark soft shell turtle is listed in Appendix I of the Washington Convention on the Protection of Species (CITES). Wild animals are not allowed to be traded, offspring are subject to severe trade restrictions, and proof of legal import or breeding of legally imported animals is required for keeping in the CITES contracting states. The EU species protection regulation ( Regulation (EC) No. 338/97 ) lists the dark softshell turtle in Appendix A.
Tortoises are protected in Bangladesh by the Bangladesh Wildlife Protection Act, 1973 and the Bangladesh Wildlife Conservation Amendment Act, 1974. Since 1998, the capture and trade of wild turtles has been completely banned. Nevertheless, rare and endangered turtles are still traded, including close relatives of the dark softshell turtle because of their particularly tasty meat.
In India, the dark softshell turtle is listed on Schedule IV of the Indian Wildlife (Protection) Act of 1972. Regardless of the ban, there is still a trade in turtles in Assam's largest city, Guwahati , for meat use and as pets. Local fishermen reported a decrease in the number of animals caught around 2010.
The Indian populations of the dark softshell turtle are also hunted for the local meat trade. It is of particular importance that the previously strictly observed taboos , with which the indigenous peoples also ensured the protection of natural resources, are becoming increasingly less important. In their place came ruthless exploitation. Members of indigenous peoples no longer only hunt the turtles for their own needs, but also plunder the clutches to eat the eggs and to sell them on the local markets.
Since 2002, Chittagong has been aiming to release turtles that have migrated to the wild. However, the staff at the Bistāmī Shrine who are responsible for caring for the turtles have only basic knowledge of animal care and the number of young animals could not be increased to such an extent that they could be released into the wild. Improved training for animal keepers should remedy this.
With reference to the Indian temples where turtles are kept, it is emphasized that they could play an important role in ex situ conservation of the species. This is mainly because of the protection that is granted to the sacred animals in the Hindu temple complexes. Indian conservationists have been trying to improve the keeping conditions for temple softshell turtles in selected temples in India since 2013. The aim is to start a conservation breeding program with the temple populations and to reintroduce them to the wild.
Systematics
Nilssonia nigricans is one of about half a dozen species of the Indian softshell turtles ( Nilssonia ). It belongs to about thirty species in ten genera of the subfamily common softshell turtles (Trionychinae). With seven other species in the subfamily flap-shelled turtles (Cyclanorbinae) it forms the family softshell turtles (Trionychidae), which in turn superfamily with a second monotypic family softshell turtles Related forms (Trionychoidea). Thus Nilssonia nigricans belongs to the suborder Halsberger tortoises (Cryptodira), which are characterized by the ability to retract their head into the shell in an upright position. The Halsberger tortoises are the significantly larger of the two sub-orders of the tortoises .
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| Cladogram of the genus Nilssonia |
Based on phylogenetic and molecular genetic studies, the genus Aspideretes was synonymous in 2007 with the genus Nilssonia , which had been monotypical with Nilssonia formosa . Within the genus, the dark softshell turtle is the sister taxon of the peacock-eye softshell turtle ( Nilssonia hurum ). This clade is opposed to a clade from the Ganges softshell turtle ( Nilssonia gangetica ) and Leith's softshell turtle ( Nilssonia leithii ). The clade with these four species is the sister taxon of Nilssonia formosa .
Synonyms and misspellings
- Trionyx nigricans Anderson , 1875
- Amyda nigricans , Mertens, Müller & Rust , 1934
- Aspideretes nigrican Meylan , 1987
- Trionix nigricans Richard , 1999
- Aspideretes nigricans ( Anderson , 1875)
Web links
- Nilssonia nigricans onthe IUCN Red List of Threatened Species . (English)
Map with all coordinates: Individual evidence
- ↑ Don Moll and Edward O. Moll: The Ecology, Exploitation, and Conservation of River Turtles . Oxford University Press, Oxford u. a. 2004, ISBN 0-19-510229-0 , p. 31.
- ↑ a b c d e f g h i j M. Firoz Ahmed and Abhijit Das: Tortoises and Turtles of Northeast India: Saving them from Extinction! Survey, Assessment of Present Status and Conservation of Tortoises and Freshwater Turtles in Northeast India . Aaranyak, Guwahati, Assam 2010, digitized .
- ↑ a b c d e f Indraneil Das: The turtles of the Indian subcontinent . Edition Chimaira, Frankfurt am Main 2001, ISBN 3-930612-35-6 , pp. 85-86.
- ↑ a b c d e Peter CH Pritchard : Encyclopedia of Turtles . TFH Publications, Neptune, NJ 1979, ISBN 0-87666-918-6 , pp. 644-646.
- ↑ a b c d e f g h i j Subhasish Das et al .: Conservation Status of Black Soft Shell Turtle (Nilssonia nigricans) in Bangladesh . In: Journal of Wildlife Research 2018, Volume 6, No. 2, pp. 12-16.
- ↑ a b c d Chittaranjan Baruah et al .: Community Awareness and Capacity Building for Endangered Turtle Conservation in northeast India . Conservation Leadership Program, Guwahati 2011, digitized .
- ↑ a b Md. Farid Ahsan and Md. Abu Saeed: Some aspects of the breeding biology of the black softshell turtle, Aspideretes nigricans . In: Hamadryad 1992, Volume 17, pp. 28-31, ZDB -ID 920308-4 .
- ↑ a b c d M. Farid Ahsan and M. Abu Saeed: Bostami turtle (Aspideretes nigricans) no longer endemic only to Bangladesh . In: Tigerpaper 2009, Volume 23, No. 2, pp. 29–32, digitized version (entire issue).
- ↑ a b c Turtle Conservation Coalition (Ed.): Turtles in Trouble: The World's 25+ Most Endangered Tortoises and Freshwater Turtles - 2011 . IUCN / SSC Tortoise and Freshwater Turtle Specialist Group, Lunenburg, MA 2011, digitized .
- ↑ a b c d e Nicole Liebing et al .: Molecular phylogeny of the softshell turtle genus Nilssonia revisited, with first records of N. formosa for China and wild-living N. nigricans for Bangladesh . In: Vertebrate Zoology 2012, Volume 62, No. 2, pp. 261-272, digitized .
- ↑ a b c Shantanu Kundu et al .: Environmental DNA (eDNA) testing for detection of freshwater turtles in a temple pond . In: Herpetology Notes 2018, Volume 11, pp. 369–371, digitized .
- ↑ a b Shiv Sahay Singh: Under divine care, turtles swim on in Assam's temple tanks . In: Under divine care, turtles swim on in Assam's temple tanks , The Hindu , June 12, 2018, accessed May 30, 2019.
- ↑ Kamakhya Temple. In: Kamakha Temple - kamakya-temple.com. Retrieved April 13, 2020 .
- ↑ a b c Jayaditya Purkayastha: Urban biodiversity: an insight into the terrestrial vertebrate diversity of Guwahati, India . In: Journal of Threatened Taxa 2018, Volume 10, No. 10, pp. 12299-12316, doi: 10.11609 / jott.3721.10.10.12299-12316 .
- ↑ a b c Dipa Rani Devi and Maitrayee Mishra: Survey of temple tanks as a reference for conservation of turtle fauna in Kamrup (Rural and Metropolitan) District . In: International Journal of Science, Environment and Technology 2017, Volume 6, No. 2, pp. 1335–1342, digitized .
- ^ A b Don Moll and Edward O. Moll: The Ecology, Exploitation, and Conservation of River Turtles . Oxford University Press, Oxford u. a. 2004, ISBN 0-19-510229-0 , pp. 233-235.
- ^ A b Hafiz All Hosen and Idris Miah: Marketing of Freshwater Turtles and Tortoises in Different Markets of Rangpur Division, Bangladesh . In: Global Veterinaria 2014, Volume 13, No. 4, pp. 496–502, doi: 10.5829 / idosi.gv.2014.13.04.8610 .
- ^ A b Don Moll and Edward O. Moll: The Ecology, Exploitation, and Conservation of River Turtles . Oxford University Press, Oxford u. a. 2004, ISBN 0-19-510229-0 , p. 18.
- ↑ Anders GJ Rhodin et al .: Turtles of the World: Annotated Checklist and Atlas of Taxonomy, Synonymy, Distribution, and Conservation Status (8th Ed.) (= Chelonian Research Monographs (ISSN 1088-7105) No. 7) . Chelonian Research Foundation, Lunenburg, MA 2017, doi: 10.3854 / crm.7.checklist.atlas.v8.2017 .
- ↑ a b Abhik Gupta: The Beleaguered Chelonians of Northeastern India . In: Turtle and Tortoise Newsletter 2000, No. 6, pp. 16-17.
- ↑ Uwe Fritz and Peter Havas: Checklist of the Chelonians of the World . In: Vertebrate Zoology 2007, Volume 57, No. 2, pp. 149-368, digitized .