LM: Valves dorsiventral, moderately arched, with triundulate, convex dorsal margin, straight to slightly concave ventral margin (Figs 1–9). Valve ends protracted, capitate. Dimensions: length 34.3–40.8 μm, width 5.4–6.9 μm. Axial area very narrow, central area indistinct. Raphe arched, proximal ends weakly expanded, slightly dorsally deflected, distal ends dorsally deflected. Dorsal striae with fine punctuation, slightly radiate throughout, 23–25(27) in 10 μm dorsally at valve centre, 24–27 in 10 μm ventrally, 28–30 in 10 μm near valve ends.

SEM: Externally, raphe located in flat, narrow ledge, slightly wider in valve centre (Figs 10, 11, 14, 17). Ledge ornamented with shallow, non-penetrating depressions, rounded or irregular in shape with variable size (Figs 14, 17). Striae uniseriate, composed of elongate areolae of variable length (Fig. 10–19). Dorsally, striae continuing uninterrupted onto mantle, mantle with 3–4 rows of areolae of variable length in valve centre, and one row of elongate areolae near valve ends (Figs 12, 13). Ventrally, striae composed of one row of transapically elongated areolae (Figs 11, 14–16). Girdle bands open, each bearing one or two rows of rounded or slightly transapically elongated poroids similar in size to ventral areolae (Figs 14–16, 20, 24). Internally, distal raphe ends slightly ventrally deflected terminating in large helictoglossae (Figs 22, 23). Proximally, raphe ends terminating in wide fused central helictoglossa (Fig. 25).

Type: — CHINA. Sichuan Province: Tibetan Autonomous Prefecture of Garzi, Daocheng County, Haizishan Nature Reserve, Lake Congqiancuo, 29°21′58″ N, 100°04′51″E, elevation 4389 m a.s.l., samples collected by Q.C. ZHOU, 20 Sep. 2018. Holotype NMW.C.2019.01! Amgueddfa Cymru — National Museum Wales, isotype slide CQC1#, SHOU! Department of Hydrobiology, College of Fisheries and Life Science, Shanghai Ocean University (SHOU), Shanghai.

Etymology: —The specific epithet ‘ daochengensis ’ refers to the locality from which the new species was described.