Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 October 2022 | 14(10): 22029–22031
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.7908.14.10.22029-22031
#7908 | Received 08 March 2022 | Final
received 21 September 2022 | Finally accepted 28 September 2022
New distribution
record of Black Softshell Turtle Nilssonia
nigricans (Anderson, 1875) from Manas National
Park, Assam, India
Gayatri Dutta 1,
Ivy Farheen Hussain 2, Pranab Jyoti Nath
3 & M. Firoz Ahmed 4
1,2,4 Tiger Research and
Conservation Division, Aaranyak, Guwahati, Assam
781028, India.
3 Assam Forest
Department, Manas National Park, Assam 781315, India.
1 gayatri@aaranyak.org
(corresponding author), 2 ivy@aaranyak.org, 3 pronabjyotinath955@gmail.com,
4 mfa.aaranyak@gmail.com
Editor: Raju Vyas, Vadodara,
Gujarat, India. Date of
publication: 26 October 2022 (online & print)
Citation: Dutta, G., I.F.
Hussain, P.J. Nath & M.F. Ahmed (2022). New distribution record
of Black Softshell Turtle Nilssonia
nigricans (Anderson, 1875) from Manas National
Park, Assam, India. Journal of Threatened Taxa 14(10): 22029–22031. https://doi.org/10.11609/jott.7908.14.10.22029-22031
Copyright: © Dutta et al. 2022. Creative Commons
Attribution 4.0 International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: None.
Competing interests: The authors
declare no competing interests.
Acknowledgements: The authors express their gratitude to Mr.
Amal Chandra Sharma, former field director of the Manas
TR for his encouragement to publish this record. Our special thanks to the Manas Tiger mobile patrol team of Bhuyanpara
Range, Mr. Kameswar Baro,
I/C Bhuyanpra Range, Manas
National Park for their assistance in field. We would like to thank Aaranyak and Panthera for their
support.
Nilssonia
is a genus of softshell turtles under the family Tionychidae
distributed widely in southern Asia including Pakistan, India, Afghanistan,
Nepal, Bangladesh, and Myanmar (Rhodin et al. 2021).
The Black Softshell Turtle Nilssonia
nigricans is listed as ‘Critically Endangered’ and the population is
decreasing as per the latest IUCN Red List (Praschag
et al. 2021). Back in 2002, the IUCN Red
List categorized the N. nigricans as ‘Extinct in the wild’ (IUCN 3.1) -
only surviving in restricted temple ponds in Bangladesh and Assam (IUCN Red
List 2002). But gradually, individuals started getting reported from the
Brahmaputra River Basin in India as well, Meghna River Basin in Bangladesh (Praschag et al. 2021), and Koach
Behar of West Bengal (Yasmin et al. 2021). It is also known to be distributed
in some isolated sub-populations in several temple ponds of Assam and Tripura (Praschag & Gamel 2002; Ahmed
& Das 2010). The presence of N. nigricans has been reported from Kaziranga National Park, Nameri
Tiger Reserve, and Pakke Tiger Reserve, and may also
be distributed in Assam’s Kaziranga-Orang Riverine
Landscape (KORL) (Ahmed & Das 2010). Little is known about its distribution
and much work needs to be done concerning its habitat and ecology. This diurnal
large softshell turtle inhabits large rivers and wetlands but its diet in the
wild is still unknown, while in the temple ponds, its diet consists of
different types of fruit, animal viscera and other substances like puffed rice
and bananas (Ahmed et al. 2009).
This
species is also observed in wildlife trade as documented from the Brahmaputra
River basin (Baruah & Sharma 2010). The targeted exploitation pressure on
this species is also known for human consumption but with a small range (Praschag et al. 2021). However, N. nigricans is
facing extensive local exploitation including sustained and targeted egg
collection for local consumption (Ahmed & Das 2010).
During
a field visit to the Manas National Park, we came
across a large softshell turtle in a stream (Durabeel
Nala of Rupahi River)
located in the transitional area between woodland and grassland (26.72°N &
91.075°E) (Figure 1). It was sighted at around 1000 h on 02 May 2021. The
turtle was identified as a Black Softshell Turtle N. nigricans using
description and taxonomic keys (Prachag & Gamel 2002; Ahmed et al. 2009). In addition to the
characters observed on several live specimens along with the one presented with
photographs here: a. High dome carapace grey in colour
(Image 2); b. Mid-dorsal carapace concave; c. Distinct groove between the bony
carapace and the cartilaginous flaps; d. a visibly sharp fall of carapace dome
to the posterior (in lateral view (Image 1)); and e. Thick and muscular nuchal
fold on carapace.
This
is the first confirmed distribution record of the N. nigricans with an
adult individual from the Manas National Park, Assam.
Earlier, Ahmed & Das (2010) observed small (app. 4 cm carapace width) young
ones in streams originating inside Manas NP which were
believed to be juvenile N. nigricans. This observation confirms that the
species is also found in protected areas other than the PAs mentioned above,
increasing its population coverage to more PAs.
This also signifies that the species uses more tributaries of the
Brahmaputra river to inhibit in addition to the Jia Bhoroli
river, that flows by the Nmaeri TR and Pakke TR on the north bank of the Brahmaputra. This
occurrence is reported from a stream of the Pahumara
River, a tributary of Beki River that drains into the Brahmaputra River in
western Assam.
The
Manas National Park (26.6594° N, 91.0011° E) is
located in the Bodoland Territorial Region (BTR) of Assam in the districts of Baksa and Chirang and spread over
an area of 500 km2 (Das et al. 2014). It is located in the
sub-Himalayan landscape of northeastern India, contiguous with the Royal Manas National Park, Bhutan, and forms the core of the
Indo-Bhutan Transboundary Manas Conservation Area (TraMCA) that covers app. 6,500 km2 area (Borah
et al. 2013). It falls under the Key Conservation Area- Jigme Dorji-Manas-Bumdaling conservation landscape in the eastern
Himalayan ecoregion (Wikramanayake
et al. 2001). In and around Manas National
Park, the turtles and their habitats are threatened by loss of habitats due to
extensive siltation of riverbed (landslide and mining in Bhutan hills),
overfishing, and catching of turtles for meat consumption. The population of
this species might be affected given the above threats over the last
two-to-three decades. Systematic efforts are needed to study and monitor this
species to understand the ecology, food habit, and conservation threats
associated.
For
images - - click here for full PDF
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