Fusconaia burkei
Fusconaia burkei, the tapered pigtoe, is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels. This species is endemic to North America. It has been a federally listed threatened species under the authority of the Endangered Species Act of 1973 since 2013. Original description This species, originally called Quincuncina burkei, was first described by Bryant Walker in 1922. Walkers's original text (the type description) reads as follows: Quincuncina burkei Walker. Plate I, figs. 1 and 4. Shell of moderate size, subrhomboid, very inequilateral, subsolid, somewhat inflated; beaks only slightly elevated above the hinge-line, their sculpture consisting of strong, subcircular ridges, stronger along the umbonal ridge and curved up sharply behind, fading out anteriorly and becoming nearly parallel with the growth-lines; anterior end regularly rounded; base line curved; posterior end somewhat produced, subtruncate, curving down rather abruptly and subangulated as it approaches the posterior point, which is below the median of the disk; posterior ridge strong and angulated by the junction of the surface ridges; posterior slope with strong ridges, curving upwards, extending from the posterior ridge to the posterior margin, these form a sharp angle on the posterior ridge with heavier ridges extending