This study identifies one diatom species as Tabularia fonticola (Hustedt) C.E. Wetzel & D.M. Williams after examining the specimens collected from the Wu River, which runs through the Suining County of Hunan Province, by using light and scanning electron microscopy. The observation results demonstrate that the identified T. fonticola has the following diagnostic characters: (1) linearlanceolate valve outline with wide sternum and shortened and wide striae. (2) Thickened silica virgae and vimines. (3) Areola occluded by cribrum composed of a few transapical silica bars. (4) Only one rimoportula produced at an apex for each valve. (5) Ocellulimbus with regularly arranged porelli. (6) Open valvocopula. This article reports the ultrastructure characters of the prenormal frustule of T. fonticola for the first time. The study results not only improve the understanding of the ultrastructure of T. fonticola, but also add a new geographical distribution region for it.