Ordovician graptolites from the Early Hunneberg of southern Scandinavia

A graptolite fauna of Early Hunneberg age is described from southern Scandinavia (Scania, Vastergotland, Oslo region). Correlation and boundaries within the interval are discussed and it is suggested that the Hunneberg Stage be elevated to series rank, interposed between the Tremadoc and the Arenig. One new dichograptid genus, Hunnegraptus, and three Scandinavian representatives of it, H. copiosus, H. tjernviki, and H. robustus, are erected. The genus is multiramous, with long first-order stipes, and shows presumed rejuvenation of gerontic specimens. It is likely to be most closely related to Clonograptus. Six additional species are formally named: Kiaerograptus supremus (Anisograptidae), Clonograptus (C.) magnus, Tetragraptus longus, T. krapperupensis (Dichograptidae), Paradelograptus elongatus, and P. tennis (Sinograptidae). The sequence containing these taxa is divided into three zones: the K. supremus Zone which probably starts in the Late Tremadoc, the A. murrayi Zone, and above that the H. copiosus Zone, which underlies the Late Hunneberg Tetragraptus phyllograptoides Zone. The fauna covers part of the interval when anisograptids gave way to graptolites of the dichograptid development stage, and the observed steps in this evolution (loss of bithecae) are described.