A new species of a testate amoeba, Matsakision ogawaraensis sp. nov., is described from Ogawara pond, Aomori Prefecture, Japan. This is the third species in the genus Matsakision. Matsakision ogawaraensis sp. nov. is distinguished from two other species by the specific form of the shell in apertural view, which is triangular (the shells of other species are circular or elliptic). In addition, it has a chitinous lip around the aperture. For the first time, long needle-like pseudopodia have been observed.