|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Rhynchonellata - Orthida - Plectorthidae
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|L. E. Popov and L. R. M. Cocks 2006||Ventribiconvex shell about 75 per cent as long as wide, with maximum width at mid length, about 60–70 multicostellate ribs, subcarinate ventral valve and a weak dorsal sulcus fading anteriorly.
Shell subequally biconvex, transverse and subrectangular in outline, about 75 per cent as long as wide. Hinge line slightly shorter than maximum width at mid length. Cardinal extremities rounded. Anterior commissure gently sulcate. Ventral valve subcarinate, gently convex in lateral profile, with maximum height at about one-third valve length from beak. Interarea low, apsacline, with open delthyrium. Dorsal valve gently convex with linear, orthocline interarea and shallow sulcus originating at umbo and fading anteriorly. Radial ornament slightly unequally multicostellate with first generation of ribs bifurcating at about 2–3 mm from umbo and with 4–7 ribs per 3 mm along anterior margin and about 60–70 costellae along anterior margin of mature specimens. Concentric ornament of fine, evenly spaced, elevated fila about 8–10 per mm.
Ventral interior with strong teeth supported by long, diverging, dental plates. Ventral muscle field transverse suboval, about 30 per cent as long as valve. Strongly impressed adductor scars divided by subtriangular diductor scar strongly raised anteriorly. Ventral mantle canals saccate with diverging vascula media. Dorsal interior with low notothyrial platform and subtriangular brachiophores with slightly diverging bases and deep sockets with fulcral plates. Ridge-like cardinal process with crenulated myophore. Dorsal adductor muscle field small, subquadrate in outline, about 40 per cent as long as valve, divided medially by broad ridge. Mantle canal system lemniscate.