The Morphology and Systematics of Didymograptus fasciculatus Nicholson, 1869

A new description of “Didymograptus” fasciculatus Nicholson, 1869, is given on the basis of specimens from the Skiddaw Slates (Zone of Didymograptus bifidus) some of which are preserved in relief. The uniramous rhabdosomal form is confirmed. The presence of prothecal folds indicates that the species belongs in the family Sinograptidae Mu, 1957, and adoption of the generic name Nicholsonograptus, proposed by Bouček and Přibyl (1951) with “ D. ” fasciculatus as the type species, is recommended. The possibility that Nicholsonograptus fasciculatus is an intraspecific variant of Holmograptus lentus (Törnquist, 1911) is discussed.