Ninadiscus[1] is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi (1943),[2] Order Agnostida Salter (1864).

Ninadiscus is known from the Lower Cambrian (Botomian) of northwestern Mongolia (Egyngolskaya Suite) and the USA (New York).

[4] Like all Weymouthiidae, Ninadiscus lacks eyes and facial sutures, with the glabella tapering gently forward, rounded frontally and extending to the anterior border furrow.

Two transglabellar furrows (S1 and S2) are well impressed (maximum cephalic width opposite S1).

The long and narrow pygidial axis is composed of 10 rings and almost reaches the posterior margin.