A first distribution record of the Indian Peacock Softshell Turtle Nilssonia hurum (Gray, 1830) (Reptilia: Testudines: Trionychidae) from Mizoram, India

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The trionychid turtle species composition remains poorly documented in Mizoram. So far, only three turtle species under this family have been reported by previous workers. Here, we report the occurrence of the Indian Peacock Softshell Turtle Nilssonia hurum (Gray, 1830) based on two individuals collected from Buhchangphai and Serlui, Mizoram, India. Chelonians are by far the most ancient quadruped vertebrates on Earth and are widely distributed in India (Das 1985(Das , 1995(Das , 2002. Having one of the most diverse chelonian fauna in the world, India is currently inhabited by 30 species of freshwater turtles and tortoises and six marine turtles (Ahmed et al. 2009;Das & Gupta 2015) including the recent record of Manouria impressa by Mital et al. (2019). Eight species of turtles belonging to the family Trionychidae (Reptilia: Chelonia) are known to occur in the country, viz., Nilssonia gangetica, N. hurum, N. leithii, N. nigricans, Chitra indica, Amyda cartilaginea, Pelochelys cantorii, and Lissemys punctata which comprises three subspecies-L. punctata punctata, L. punctata andersonii, and L. punctata vittata (Das 1990(Das , 1996Bhupathy et al. 1992;Frazier & Das 1994;Choudhury 1995;Datta 1998;Sengupta et al. 2000;Pawar & Choudhury 2000;Praschag & Gemel 2002;Praschag et al. 2011). Till date, little is known about the distribution pattern and the actual species composition of trionychid turtles in Mizoram State, however, three distinct species are currently known to occur, namely, L. punctata, P. cantorii (Matthew 2007), and A. cartilaginea (Pawar & Choudhury 2000;Hmar et al. 2020).
The conservation status of N. hurum is presently listed as Vulnerable in the IUCN Red List (Das et al. 2010), Appendix I in CITES, and is also categorized as Schedule I under Wildlife Protection Act, 1972 in India (Das & Gupta 2011). In India, it was first reported by Annandale (1912a) from Puri, Orissa (Odhisha). It is commonly J TT known as the Indian Peacock Softshell Turtle, widely distributed in the northern and central parts of the Indian sub-continent; at tributaries of the rivers Indus, Ganga, Brahmaputra, and Subarnarekha (Smith 1931;Moll & Vijaya 1986). It was also reported from isolated water bodies of Maharashtra (Varghese & Tonapi 1986), Madhya Pradesh (Das 1987), Rajasthan (Bhupathy & Kumar 1988), Uttar Pradesh (Pai & Basu 1988), and Manipur (Singh 1995 (Manhas et al. 2018). Outside India, its distribution ranges include eastern Pakistan, Bangladesh, and Nepal (Mertens 1969;Das 1989;Mitchell & Rhodin 1996;Schleich & Kastle 2002;Noureen et al. 2008). In this paper, we report two individuals, male and female of Nilssonia hurum from Kolasib District which represents the first record for Mizoram State, northeastern India. While

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The second individual was sighted on 23 July 2020 from a fish pond ( The two individuals were identified as the Indian Peacock Softshell Turtle Nilssonia hurum based on the identification key provided by Annandale (1912b), Rashid & Swingland (1997), Praschag et al. (2007), and Das et al. (2010). According to Das et al. (2010), the sex of the first individual was identified as a female due to its short tail and cloaca positioned close to the base of the tail and the second one as a male as the tail is thick, long and edgeless; also, the cloaca positioned close to the

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tip of the tail. After morphometric measurements were taken with the help of a measuring tape nearest to 1mm, both individuals were handed over to the field staff to be released into the natural habitat with the permission issued by the Chief Wildlife Warden, Department of Environment, Forest and Climate Change, Government of Mizoram. Details of both individuals are given in Table 1. The individuals have a large head and snout strongly turned down; the head and limbs are olivegreen; forehead with dark reticulations and large yellow or orange patches or spots, especially behind the eyes and across the snout, that are larger than those in its sister species, N. nigricans; carapace low and oval, dark olive green to nearly black sometimes with a yellow rim and the anterior edge has blunt tubercles. The juveniles have four striking, orange ringed dark-centered ocelli that are subequal and symmetrically positioned on an olive green carapace with dark reticulation; the markings becoming obscured with growth. The plastron is dark in juveniles, turning light grey in adults. Males possess relatively longer and thicker tails than females, with the cloaca situated close to the tail-tip. No sexual dimorphism in shell colour or patterns or size has been reported (Das et al. 2010). Das et al. (2010) reported that the Indian Peacock Softshell Turtle utilizes rivers, lakes, and ponds, from the upper reaches of the rivers, to the lowest, while apparently avoiding the saline river mouths. Its ability to burrow into the mud may be associated with its ability to inhabit ponds and other lentic environments that may dry up during the dry season. Adults were observed to utilize deeper sections of the river, while yearlings appear to stay in the shallower parts. Rashid & Swingland (1997) mentioned that the species migrates from drying ponds, and are known to bask on the surface of the water.
The vegetation of the present surveyed area falls under the tropical wet evergreen forest and tropical semi-evergreen forest associated with moist deciduous forest corresponding to the Cachar tropical evergreen 1B/C3 and semievergreen 2B/C2 forest (Champion & Seth 1968) (Fig 1). The average annual rainfall of Kolasib District is 2,703mm and temperature ranges 23°C-35°C (NIC 2020). The closest published locality record for this species is in Rukri River, Hawaithai, Cachar District, Assam (24.5°N & 92.8° E) (Das & Gupta 2011), which is approximately 29.9km from the first distribution record and 24.9km from the latter to the south. Being the components of Barak drainage system, the three collection sites, Chhimluang, Serlui, and Rukri rivers join later in Assam that suggested the possibility of dispersal in between these two states. Due to construction of Serlui B Dam for hydroelectric power in 2006 that was completed in 2009, the dam creates a reservoir catchment area of ca. 53km 2 that drastically altered the natural habitat of these valuable species. Moreover, it had been reported that turtles and tortoises in these areas are commonly hunted for meat and trade by the local people and we suggest that a proper assessment on their conservation measures needs to be initiated.