A revision of the Upper Ordovician brachiopod "Pentamerus angulosus Törnquist"

The species Pentamerus angulosus Törnquist is best known from the illustrations of Angelin & Lindström (1880). These authors based their description on a sample of seven shells, which is here shown to be composed of four distinct brachiopod stocks. More importantly, examination of Törnquist's original material shows that the type of shell illustrated by them as angulosa docs not occur in Törnquist's large, essentially conspecific, sample whose shells, not unexpectedly, possess more markedly angular ribbing. The name Parastrophina angulosa (Törnquist) is therefore accorded to an appropriate Törnquist shell, and the species redescribed biometrically from his sample. The name Parastrophina lindstroemi is erected for specimens hitherto masquerading as the species angulosa.