The identity of Didymograptus (Expansograptus) suecicus (Tullberg) and related species (Graptoloidea, Dichograptidae)

The horizontal didymograptid species Didymograptus (Expansograptus) suecicus Tullberg, D. (E.) holmi Törnquist and D. (E.) similis (J. Hall) are redescribed using the type material and additional specimens. Their exact proximal structures are revealed for the first time from relief material. All three species can easily be differentiated taxonomically and also show differences in their biostratigrapnic distribution.