The systematic position of Pseudolingula Mickwitz and related lingulacean brachiopods

The systematic position of the genus Pseudolingula Mickwitz is re-examined in the Light of a new study of the Upper Ordovician (uppermost Caradoc) type species P. quadrata (Eichwald) from Estonia. Although the genus has been placed previously within the obolide subfamilies Lingulellinae or GlosseIIinae, this study shows that it is referrable to neither. P. quadrata díffers in: (1) its musculature, which shows both obolide and lingulide affinities, but has a divided umbonal muscle in both valves; (2) vascular markings, which lack aIl evidence of the dorsal vascula media and approach a lingulide bifurcate condition, and (3) pseudointerareas, which show similarities with, e.g., Recent Lingula adamsi. The new obolide subfamily Pseudolingulinae is proposed.