The black mussel, Choromytilus meridionalis, occurs in the same area as P. perna and differs by color and the absence of a pitted resillal ridge (Schurink and Griffiths, 1990) (Gulf States Marine Fisheries Commission, 2003).
bay mussel (English), blue mussel (English), Mediterranean mussel (English), Mittelmeer-Miesmuschel (German)
Two similar tropical species occur along the south coast of Africa. Mytilus galloprovincialis, the larger European mussel, is similar to P. perna in shape and color and is located along the southwestern coast of Africa (Schurink and Griffiths, 1990). This species is extending its range on the east coast of Africa at the expense of P. perna by out-competing the brown mussel due to a resistance to specific parasites (Ugarteburu and McQuaid, 1998) (Gulf States Marine Fisheries Commission, 2003).
P. perna (brown mussel) is indigenous to Africa and the western coast of South America. P. perna has a more saturated brown color with small occasional patches of green. Until recently, Perna viridis and P. perna were geographically isolated and thus easily distinguished, however their recent expansions have made proper identification more reliant on detailed morphological features (DeVictor and Knott, UNDATED).