Taxonomy of the fouling cheilostome bryozoans Schizoporella unicornis (Johnston) and Schizoporella errata (Waters)

The cheilostomes Schizoporella unicornis (Johnston, 1847) and Schizoporella errata (Waters, 1878) have been used as model species in several ecological and taxonomic studies. However, these species have been consistently misidentified in a large percentage of such works. Here, full taxonomic descriptions of both species, based largely on scanning electron micrographs of type specimens, are presented. A lectotype is chosen for S. errata and it is shown that the species described as 'Lepralia unicornis Johnson MS' from the Pliocene Coralline Crag by Wood (1844) is not conspecific with Johnson's L. unicornis introduced for recent material three years later. This work has implications for the application of seemingly cosmopolitan species to the study of anthropogenic disturbance and identifies the need for molecular characterization of cryptic species complexes.