Genus: Test ovoid, symmetrical, compressed, composed of a transparent membrane with or without adherent extraneous particles (Cash & Wailes, The British Freshwater Rhizopoda and Heliozoa vol. III, 1915). Species: Test covered with many grains of quartz and various extraneous particles, 55-97 μm long, 31-74 μm wide; pseudostome lacking any collar, cytoplasm containing algal endosymbionts (Cash & Wailes, The British Freshwater Rhizopoda and Heliozoa vol. III, 1915).

31 μm 63 μm 94 μm; x 640

Amphitrema stenostoma Nüsslin, test 75 μm long, 62 μm wide, L/W=1.2, x 640, No.3, Yahei-daira-shitsugen (Yahei-daira marsh), North of Higashidaiten, Azuma mountains, Yonezawa city, Yamagata Pref., Japan, July 1, 2007 by Y. Tsukii
31 μm 63 μm 94 μm; x 640

Test 78 μm long, 58 μm wide, L/W=1.3, x 400, x 640

Test 80 μm long, 60 μm wide, L/W=1.3, x 400, x 640

Test 80 μm long, 63 μm wide, L/W=1.3, x 400, x 640

Amphitrema stenostoma Nüsslin, test 80 μm long, 60 μm wide, L/W=1.3, x 640, No.3, Yahei-daira-shitsugen (Yahei-daira marsh), North of Higashidaiten, Azuma mountains, Yonezawa city, Yamagata Pref., Japan, July 1, 2007 by Y. Tsukii
31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.3, Yahei-daira-shitsugen (Yahei-daira marsh), North of Higashidaiten, Azuma mountains, Yonezawa city, Yamagata Pref., Japan, July 1, 2007 by Y. Tsukii