Validation of the names of two new species of Codium (Chlorophyta, Bryopsidales) from Isla Guadalupe and Rocas Alijos, Pacific Mexico and the southern California Channel Islands, with some remarks on insular endemism.

The names Codium schmiederi and Codium dawsonii are validated by the provision of designated types. The species to which the invalidly published name C. schmiederi applies is known only from Isla Guadalupe and Rocas Alijos, Baja California, Mexico. The history of phycological exploration of these two remote localities is detailed. The species to which the invalidly published name C. dawsonii applies is found in those two localities as well as on coastal islands of Baja California and southern California. It is seldom found on the mainland. Codium hubbsii, originally described from Islas San Benito, has a distribution similar to that of C. dawsonii, but occurs more often on the mainland. The distributions of these three species constitute a pattern of insular endemism. [ABSTRACT FROM AUTHOR]