I wrote a few lines for a forum recently about huge number and variety of nature reserves in India:

India has many many nature reserves / national parks with a huge range of wildlife and environments. Many species are endemic to only India. Some notable places to look up are:

Gir National Park- only place in the world where you can see the Asiatic Lion
Ranthambore – one of the best managed tiger reserves & has a beautiful ruins of a medieval fort inside the park. (lan
Sunderbans- largest tiger santuary in the world. mangrove & swamp environment with a huge crocodile population. The tigers here are reputed to be man-eaters.
Kaziranga- home to the Indian rhino (closed most of the time these days)
Periyar- tiger and elephant reserve
Corbett – tiger reserve in the Himalayan foothills
Bharatpur- one of the foremost bird santuaries in the world. Winter grounds for the rare Siberian crane
Gahirmatha- Nesting ground for the endangered Olive Ridley turtles
Namdhapha- High in remote eastern himalayas. Home to the elusive snow leopard. Also cloud leopard and tigers
Dachigam- another himalayan santuary. home to the Hangul / Kashmir Stag and black bears
Great Himalayan National Park- spectacular views, unique flora and fauna
Hemis High Altitude National Park- highlights the unique and beautiful cold desert of Ladakh
Marine National Park, Kutch- home to the dugong and other rare marine species
Wandoor / Gandhi National Park- coral reef ecosystem in the Andaban & Nicobar Islands with excellent scuba and snorkelling opportunities

and there are many many more, a list is available here:
http://en.wikipedia.org/wiki/National_parks_of_India

India offers everything from pristine reefs, lush tropical rainforest, sandy deserts to snowy mountains, so imagine the variety of flora and fauna !