Four new species are assigned to Vogelgnathus Norby and Rexroad because of the close similarity of their Pb and ramiform elements to those of the type species, V. campbelli (Rexroad). Recognition of the four new species requires that the generic diagnosis, based almost exclusively on the morphology of V. campbelli, be modified, chiefly to accommodate greater variation in Pa element morphology. Vogelgnathus dhindsai n. sp., V. gladiolus n. sp., V. kyphus n. sp., and V. pesaquidi n. sp. all possess abbreviated, carminiscaphate Pa elements. Spathognathodus postcampbelli Austin and Husri is reassigned to the genus.
The origins of Vogelgnathus are uncertain but V. gladiolus first appeared in the early Viséan and gave rise to V. pesaquidi. The latter species appears to represent the rootstock from which V. kyphus, V. campbelli, and V. dhindsai evolved. Vogelgnathus postcampbelli evolved from V. campbelli during the late Viséan.
Vogelgnathus campbelli and, to a lesser extent, V. postcampbelli have a wide geographic distribution; the four new species, however, are currently known only from Atlantic Canada, northern England, and southwest Scotland.