Description of a new Scottocheres Giesbrecht, 1897 (Copepoda, Siphonostomatoida, Asterocheridae), including an emended diagnosis and key for the genus.

The siphonostomatoid copepod genus Scottocheres was established by Giesbrecht in 1897 and now includes nine species. Consequently, these new species introduced new characteristics that must be considered to define the genus. This study provides an emended diagnosis of the genus, describes a new species, discusses the geographic distribution and hosts of the genus, and includes a key to the species. The new species was found associated with the sponge Callyspongia in Todos-os-Santos Bay and can be distinguished from its congeners by a set of characters that includes the presence of a unique seta on the inner margin of the second endopodal segment of legs 1 to 4 and only two spines on the outer margin of third endopodal element of leg 1.