Late Wenlock biostratigraphy and the Pristiograptus virbalensis group (Graptolithina) in Lithuania and the Holy Cross Mountains

Graptolites from Lithuania and the Holy Cross Mountains comprise a succession of the lundgreni, parvus (except for the Holy Cross Mts.), nassa, praedeubeli, deubeli and ludensis biozones of the upper Wenlock, the parvus, praedeubeli and deubeli biozones being recognized for the first time in Lithuania, where a graptolite-free interval may also be distinguished. P. virbalensis Paskevicius, 1974 and the virbalensis group are not widely known, and are discussed here. Analysis of P. virbalensis shows this to be an independent taxon, closely related to P. auctus. There are three species - P. virbalensis, P.jaegeri and P. auctus - in the virbalensis group.