Documentation of herpetofaunal species richness in Tripura, northeast India

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Documentation of herpetofaunal species richness in Tripura, northeast India
  NeBIO   Vol. 3, No. 1, March 2012, 60-70   Author for correspondence Basant Kumar Agarwala  Email:    © NECEER, Imphal Documentation of herpetofaunal species richness in Tripura, northeast India  Joydeb Majumder, Partha Pratim Bhattacharjee, Koushik Majumdar  1  , Chiranjib Debnath and Basant Kumar Agarwala   Ecology & Biodiversity Laboratories, Department of Zoology, Tripura University, Suryamaninagar-799 022, West Tripura, Tripura, India. 1  Dept. of Botany, Tripura University, Suryamaninagar-799 022, West Tripura, Tripura, India. ABSTRACT Herpetofaunal biodiversity in a particular area determine the quantitative and qualitative data of habitat modifications because of their receptive nature. Hilly terrain, undulating slopes and valleys with semi-evergreen to moist deciduous forests of Tripura form heterogeneous habitats for rich herpetofaunal diversity, although it is inadequately documented from the state. In the present communication, 55 species of herpetofauna was recorded belonging to 39 genera and 15 families. Out of which, 18 species were snakes, 17 species of lizards, 3 species of turtles and 17 species of amphibians. Twenty six species are new record for the state. Twenty four species were enlisted in IUCN Red List category. Habitat preference and existing threats in the state from anthropogenic activities were also mentioned. Keywords : Herpetofauna, heterogeneous habitats, human activity, ethnic people, Tripura   Species documentation and conservation has become a priority when the study would focused especially on reptiles and amphibians because these faunal groups are more sensitive than birds and mammals (Stuart, et al.,  2004), due to habitat modification in course of anthropogenic disturbances (Van Rooy and Stumpel, 1995) and some what may be due to climate change (Bickford, et al.,  2010). Herpetofauna comprises the amphibian and reptiles, are the integral  part of both terrestrial and aquatic ecosystem. Accordingly, the identification of amphibians and reptiles and the study of their ecological characteristics are decisive for the success of actions directed to biodiversity conservation (Heyer, et al.,  1994; Raven and Wilson 1992). Majority of amphibians and reptiles are sensitive to habitat quality, while only few species are adaptable to such sensibility (Ahmed, et al.,  2009). Review of available literature revealed that prior to Menon (1975) no herpetofaunal survey has been undertaken in Tripura and only a limited study was made by Talukdar (1975), Whitaker (1979), Mansukhani and Sarkar (1981) on some particular taxa. After that, Sanyal, et al.,  (2002) reported 32 species of reptiles under 28 genera belonging to 11 families out of which 18 species have been recorded from Tripura and remaining species are likely to occur in the state. Regarding amphibians, Sarkar, et al.,  (2002) gave a detail report on amphibians of Tripura state. However, in course of time faunal habitats have been changed accordingly with human interference, over exploitation of natural resources and habitat modifications. Recently, an extended distribution of  Kaloula pulchra  from West Tripura district was reported by Bhattacharjee, et al.,  2010.  Nevertheless, despite the high potential local richness of herpetofauna in the state, it is still considered poorly sampled because studies are mostly restricted to few taxa and some locations of the state. In this background, an attempt has been made to document herpetofaunal richness in different  Documentation of herpetofaunal species richness in Tripura  Majumder   et al  __________________________________________________________________________________________________ NeBIO I I Vol. 3, No. 1, March 2012, 60-70 61   locations of Tripura state. The present study will also through light to the existing threats on herpetofauna of the state. Materials and Methods   Study area  Tripura is a small hilly state of northeast India surrounded by Bangladesh on three sides, Mizoram and Assam by one sides. Tripura is geographically lies between 22 ° 56´ to 24 ° 32´N and 91 ° 10´ to 92 ° 21´E (Fig. 1) and an integral part of the Indo-Burma global  biodiversity hotspot (Myers 2000). Topographically the state has hilly terrain with undulating slopes and valleys varying from semi-evergreen to moist deciduous and secondary bamboo brakes (Sarkar, et al.,  2002) which in turns support diverse faunal communities. The temperature of the state ranges  between 10.4 0 C in winter to 25.5 0 C in summer with an average annual rainfall 2109.3 mm. Despites small size and landscape pattern, the state is very heterogeneous and thus facilitate great degree of habitat isolation for diverse floral and faunal  biodiversity. Figure 1. Map of Tripura showing sampling locations. Sampling regime Present herpetological survey was conducted in various locations of the Tripura state (Fig. 1; Fig. 2 a,  b, c, d; Table 1). Considering the breeding season, survey was restricted to only Jun to September, 2007 and 2008. For collection of as many species as  possible, a wide range of sampling methods were adopted viz., active searching and refuge examination of aquatic vegetation, paddy fields,  bushes, waterfalls, bamboo bushes, along road sides, canals, streams, underneath of stones, logs, barks, tree holes, banks of ponds, lakes, rivers and leaf litter etc. Daytime digging of soil and humus to a depth of c. 30 cm was carried out in paddy fields and forests. Secondary information from local people living in the area regarding amphibians and reptiles were also taken by Participatory Rural Appraisal (PRA) method. Two road killed specimens was also included in this study. Beside these we also supplement our data through market survey. As we don’t have the permission to collect any live specimen, we did only photography and necessary measurements for easy identification following field identification guide by Ahmed, et al.,  2009; Das, 2002; Daniel, 1963a, b, 1975; Daniel and Sekhar, 1989; Daniels, 1997a, b, c; Smith, 1935; Smith, 1943 and Whittaker and Captain, 2004. Soon after identification specimens was released at the same habitats. Voucher photographs of available specimens are deposited in Digital Photographic Collection of the Ecology and Biodiversity laboratory, Department of Zoology, Tripura University (DPCZTU). If the photographic vouchers are present, they are indicated by [P]. Rests of the species reported in this study are combination of sightings and compared with photographic guides which are indicated by [S]. Unidentified specimens are considered as single species in this report and numbered consecutively by Arabic numerals. Results and Discussion Overall 55 species of herpetofauna was recorded  belonging to 39 genera and 15 families for Tripura state during the study. Out of which, 18 species was snakes belonging to 18 genera in five families; 17 species of lizards belonging to 10 genera in four families, 3 species of turtles belonging to 3 genera in two families and 17 species of amphibians belonging to 12 genera in five families; (Table 1, Fig. 3, 4, 5, 6). Among the snakes, Colubridae family represents maximum number of species (12 species).  Documentation of herpetofaunal species richness in Tripura  Majumder   et al  __________________________________________________________________________________________________ NeBIO I I Vol. 3, No. 1, March 2012, 60-70 62   Figure 2: (a) Semi-evergreen forest (b) Riparian secondary forest (c) Secondary woody forest (d) Water stream habitat Figure 3.  (a)  Xenochrophis piscator (b)  Rhabdophis subminiatus  (c)  Bungarus fasciatus (d)  Enhydris enhydris (e)  Dendrelaphis tristis (f)  Ptyas mucosa (g) Chrysopelea ornata (h)  Lycodon aulicus (i)  Ahaetulla nasuta (j)  Elaphi radiate (k)  Boiga ochraceus (l)  Naja kaouthia (m) Trimeresurus gramineus   (n) Typhlops diardii  Documentation of herpetofaunal species richness in Tripura  Majumder   et al  __________________________________________________________________________________________________ NeBIO I I Vol. 3, No. 1, March 2012, 60-70 63   Figure 4.  (a) Calotes versicolor (b)  Japalura sp.   1 (c)  Japalura sp.   2 (d) Calotes sp. (e)  Eutropis multifasciata (f)  Eutropis macularia  (g) Sphenomorphus maculatus  (h) Unidentified sp. (i) Varanus salvator   (j) Gekko gecko In case of amphibians, lizards and turtles, maximum number of species represented by Dicroglossidae (5 species), Gekkonidae (6 species), Trionychidae (2 species), respectively. Twenty six species was recorded first time for the state (Table 1). The distribution pattern of herpetofauna was widely varied among different habitat types of Tripura. In most cases, physiological constraints have confined the amphibians to moist habitats, added to which their dispersal capacity and strong site fidelity have further restrained them (Sinsch, 1990; Blaustein, et al.,  1994; Marsh and Pearman, 1997). Although, different type of forest ecosystems offered available resources for growing, feeding and breeding; because high floristic diversity brings seasonal variation in  prey-predator relationship which strongly depends on  plant species composition and environmental gradients. The present herpetofaunal richness may be effective indicator to predict the quality of biotic interference in those forests ecosystem.  Rhabdophis  subminiatus Schlegel (Fig. 3b) efficiently adapted in diverse habitat types and frequently observed from hilly terrain to settle plain lands. In contrast, Trimeresurus graminens  (Fig. 3m) and  Japalura sp. (Fig. 4b, c) was restricted to hilly areas only. Some species are more sensitive to habitat modification ( Typhlina diardii Schlegel, Trimeresurus graminens (Shaw)  , Ahaetulla nasutus (Lacepede),  Japalura sp.,   Nilssonia nigricans (Anderson),  Hoplobatracus tigerinus Daudin). Whereas, species like  Amphiesma  stolata (Linnaeus),  Enhydris enhydris (Schneider),  Eyphlyctis cyanophlyctis  (Schneider), Varanus  salvator (Laurenti), and  Hemidactylus frenatus  Schlegel were more adaptable to habitat modifications and disturbance.  Documentation of herpetofaunal species richness in Tripura  Majumder   et al  __________________________________________________________________________________________________ NeBIO I I Vol. 3, No. 1, March 2012, 60-70 64   Figure 5.  (a)  Nilssonia nigricans (b)  Lissemys punctata (c)  Indotestudo elongata Major threats for herpetofauna of the state were the  jhum cultivation in the hilly areas, forest destruction for fodder and fuel wood collections, habitat fragmentation, illegal logging, hunting for ethno medicinal preparations, excessive use of agrochemicals and pesticides in agricultural fields, illegal trading and consumption of particular taxa (Table 1). Particularly in urban areas major threats were road killings, chemicals used for mosquito control in canals and drains. Similarly, many herpetologists opine that forest fragmentation threatens native populations by eliminating blocks of continuous habitat and is a direct negative influence of human activity (Williams and Hero, 2001). Being the state is inhabited by nineteen ethnic communities (Majumdar and Datta, 2011), more or less, there traditional food habits still today rely on some specific fauna.  Hoplobatracus tigerinus, Eyphlyctis cyanophlyctis, Fejervarya pierrei, and  Fejervarya crassus is caught extensively during monsoon and consumed by Chakma, Noatia, Jamatia, Halam, Tripuri, Kuki and Reang peoples. Most of the snake species particularly  Ptyas mucosus,    Python molurus, Ophiophagus Hannah, Naja kauthia and   Xenochrophis piscator   caught, sold in local markets and consumed by Chakma, Tripuri, Kuki and Reang community. Even they also eat eggs of snakes, lizards etc. Although, snake is worship by many  people in Tripura but they frequently kill snakes only for sheer fear. More recently the demand of Gekko  gecko  was increased due to its medicinal properties ( However, the only turtle species  Nilssonia nigricans is protected due to religious myth but the population is not increasing satisfactorily due to pollution of water by excessive  pilgrims and modification of their natural hatchery at Kalayansagar Lake of Gumati Tripura district and other two species documented in this study was found to sale in the local market.
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