A new species ofChthamalus(Crustacea: Cirripedia) characterized by enzyme electrophoresis and shell morphology: with a revision of other species ofChthamalusfrom the western shores of the atlantic ocean

Chthamalus proteussp. nov. is described as a distinct species based on its clear separation by starch-gel electrophoresis of enzymes. A redescription is given ofC. fragilis, a related species, which differs absolutely fromC. proteusin 3 out of 16 enzymes. Given the distinction ofC. proteusfromC. fragilisby enzyme methods, it has been possible to devise morphological criteria, involving simple measurement of the opercular valves and first maxilla, which can separate the two species in 99% of individuals. Although the morphological characters overlap slightly, the enzyme results show no evidence of hybridization. A species previously confused withC. proteus, C. bisinuatusfrom Brazil, differs considerably in morphology and is briefly redescribed.