“Dorsal valve only slightly sulcate, with very shallow sulcus originating in the umbonal area.”

“Its shell is considerably twisted just below the umbonal region, while its whole surface is densely striated.”

“Ventral valve lateral profile anterior to the umbo gently convex with maximum height at the umbonal region.”

“The cap is 1 30 mm broad, initially obtuse to convex, later becoming broadly umbonate.”

“The pileus is often umbonate or gibbous, and the center is often darker than the margin.”

“The pileus is first nearly cylindrical, then conic, becoming bell-shaped and finally nearly expanded, when it is umbonate.”