Originally native to the lower Brahmaputra River, the only population ever reliably known consists of 150-300 turtles in a manmade pond which is part of the HazratSultanBayazid Bastami (also transliterated "Bostami" or "Bustami") shrine at Chittagong, where they are dependent on humans for survival. To the locals and worshippers, the black softshell turtle is known as mazari ("Mazar inhabitant"); specimens from this shrine were used in the first scientific description.
The shrine's caretakers – the Mazar Committee – protect the turtle population, but will not allow specimens to be taken anymore, regardless of whether they would be killed or used for reintroduction into the wild. This is due to the animals being considered the descendants of sinners who were miraculously turned into turtles by a saint during the 13th[verification needed] century. Scientific study of the shrine's turtle population can be arranged for, however, providing the animals are not harmed.
As of 2002, the IUCN classified the species as Extinct in the Wild. However, it has since been found that in Assam at least one wild population still exists, inhabiting the Jia Bhoroli river which is a northern tributary of the Brahmaputra. Also, a population of these turtles was identified in the Kasopukhuri pond on Nilachal Hill, next to the Kamakhya Temple temple at Guwahati in Assam.
Anderson, J. (1875): Description of some new Asiatic mammals and Chelonia. Ann. Mag. Nat. Hist.4(16): 282-285.
Praschag, P. & Gemel, R. (2002): Identity of the black softshell turtle Aspideretes nigricans (Anderson 1875) with remarks on related species. Faunistische Abhandlungen23: 87-116.
Praschag, P.; Hundsdörfer, A.K.; Reza, A.H.M.A. & Fritz, U. (2007): Genetic evidence for wild-living Aspideretes nigricans and a molecular phylogeny of South Asian softshell turtles (Reptilia: Trionychidae: Aspideretes, Nilssonia). Zool. Scripta36(4): 301–310. doi:10.1111/j.1463-6409.2007.00282.x (HTML abstract)