CARBONIFEROUS ORTHOSTERNI AND THEIR RELATIONSHIP TO LIVING SCORPIONS

Five species of Upper Carboniferous orthostern scorpions are described from Britain and North America. Two are established taxa, and three a re new: Palaeopisthacanthus vogelandurdeni sp. nov., Cryptoscorpius am ericanus gen. et sp, nov., and Corniops mapesii gen. et sp. nov. An ad ditional species, Gymnoscorpius mutillidigitus gen. et sp. nov., is re ferred to the suborder Neoscorpionina, but is too incompletely known f or its systematic position to be determined more accurately. The descr iptions are based on fragmentary material from dispersed arthropod cut icle assemblages. These have yielded sufficient anatomical detail to a ssess the relationship between fossil and Recent orthostern scorpions for the first time. A cladogram is presented, demonstrating that Carbo niferous orthosterns comprise the stem group from which all Recent sco rpions (the crown group) were derived. The recognition of important ch aracter state transition series in the Orthosterni, and their polariti es, will facilitate more accurate assessment of the relationships betw een modern scorpion genera.