- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
Monograptus separatus was designated in 1958 as the species name for a group of seven subspecies with rastritiform proximal thecae and triangular distal ones. Under rules of nomenclature, however, such a group should have been designated by the oldest species among the members, so that M. separatus is here changed to M. triangulatus. The changes for the subspecies are listed.