Occurrence of a rare desmid <Tetmemorus laevis> Ralfs ex Ralfs from Yumthang Valley, northern Sikkim with a note on the genus in India

The rare desmid genus Tetmemorus Ralfs ex Ralfs with a single species T. laevis Ralfs ex Ralfs is reported for the first time from the Yumthang Valley of northern Sikkim. This genus is characterized by apical incision apart from the lateral median constriction. Only five species have been reported from different parts of India. This is the first record of the specimen from eastern Himalaya as well as northern part of India. Occurrence of the other species of the genus in India has also been discussed.