Diagnosis: Small to large, triangular to subquadrangular in outline; lateral commissure curved towards dorsal valve, anterior commissure rectimarginate to paraplicate. Beak suberect to erect, without strong beak ridges; deltidial plates conjunct as a symphytium, partly exposed; foramen small to large, mesothyridid, attrite; hinge teeth small, dental plates absent; pedicle collar very short. Cardinalia lamellar with excavate inner and outer hinge plates separated by narrow well-developed crural bases, inner hinge plates a V-shaped septalium supported by median septum, inner socket ridges steeply inclined; cardinal process absent or produced as a very small rectangular plate folded (and not supported) anteriorly; median septum low anteriorly, extending beyond mid-valve; crura short, subparallel or weakly-diverging, crural processes large and pointed. Adult brachial loop teloform (‘dalliniform’); lophophore plectolophous. (Modified from Emig 2022)