Study area, showing the areas and sites from where squid samples were obtained, also including the subareas used for the geographic differentiation in Doryteuthis sanpaulensis and D. pleii plus the shared area of co-occurrence of both species. The relative position of the study area on the South American Atlantic coast is boxed. RJ: Rio de Janeiro, SP: São Paulo, SC: Santa Catarina, RS: Rio Grande do Sul, Uy: Uruguay, MP: Mar del Plata. Subarea A: Cabo Frio (23°S) – Paranaguá (26°S), Subarea B: Paranaguá (26°S) – Santa Catarina Island (28°S). Latitudes and longitudes are decimal transformed. The 200 m isobath is showed (dashed line).