Radsia barnesii (Gray 1828)

Animal of medium size, reaching a length of 28 mm in the examined specimens. Anterior valve straight; post-mucronal slope of posterior valve straight to slightly concave. Valves quite flat. Jugal region smooth; central area with numerous uneven longitudinal ribs. Lateral triangle barely raised, with 5–7 irregular nodules. Shell color cream white with reddish brown splotches on central areas, irregular longitudinal dark reddish brown bands on lateral triangles, and occasional dark reddish brown on jugum. Girdle light greenish brown with faint trace of alternating lighter bands in some specimens. Interior of valves white (After Bullock 1988).

Bullock (1988) cites this species from Coquimbo (29°58’S; 71°21’W), to the Chonos Archipelago (45°0’0”S; 74°0’0”W), Chile. The present record (at 27°S) is now the northernmost record for this species.