Bulbochaete thanguensis Manasi Mandal & D. Maity (Oedogoniaceae) sp. nov. is described and illustrated from Sikkim Himalaya. The specimens were collected during a floristic survey in the high mountains of North Sikkim, part of Eastern Himalaya. It is morphologically superficially resembles with B. pygmaea Pringsheim ex Hirn, in having longitudinally costate oospore ornamentation with transverse lines between costae but differs in having straight, larger, dichotomously branched, elongated plant body, narrower and longer vegetative cells with wider upper end and supreme suffultory cell division. Moreover, narrower and longer oospore makes it distinct from B. pygmaea. The new species is also compared with its other two close relatives, B. pygmaea var. erecta Jao and B. tenuis Hirn var. haimensis Jao. © 2018 Magnolia Press.