Diagnosis: Small to medium sized, valves biconvex, elongate oval to subtriangular in outline; lateral commissure straight or curved towards dorsal valve, anterior commissure rectimarginate to intraplicate. Beak short, suberect to erect; beak ridges not developed; deltidial plates conjunct as narrow symphytium, exposed; foramen large, permesothyridid to mesothyridid; hinge teeth small, dental plates absent; pedicle collar very short. Cardinalia lamellar with lightly excavate inner and outer hinge plates separated by poorly- to well-developed crural bases, inner hinge plates a V-shaped septalium supported by median septum, inner socket ridges lightly inclined; cardinal process a small plate folded (and not supported) anteriorly (and bearing an oval myophore facing posteriorly); median septum extending anteriorly approximately ½ to ⅔ dorsal valve length; crura short, subparallel or weakly diverging, crural processes large and pointed. Adult brachial loop diploform (‘campagiform’) to trabecular; lophophore plectolophous. (Modified from Emig 2022)