Parambassis bistigmata is a new species of the glass perch family Ambassidae so far known from the Ranga River, Arunachal Pradesh state, and the Umtrao River, Meghalaya state, northeastern India, both of which are tributaries within the Brahmaputra River watershed.

The new species is closely-related to P. ranga.

It differs from congeners by the presence of a small, dark marking on either side of the anal-fin origin connected by a thin curved line; a well developed pre-orbital with prominent, acute spines, partially obscuring the maxilla; a black longitudinal stripe on the dorsal and ventral edges of the caudal peduncle; presence of a vague, faint, vertically-elongate humeral spot. The specific name refers directly to the two markings at the anal-fin origin.

P. bistigmata appears most closely-related to P. ranga and is a member of a group of congeners characterised by possession of a humeral spot and relatively long dorsal and anal fins as per Roberts (1995).

For more information see the paper: Geetakumari, K. 2012. Parambassis bistigmata, a new species of glassperch from north-eastern India (Teleostei: Ambassidae). Zootaxa 3317: 59-64. The abstract and introduction are available here.