Fig. 1

Distribution of Pantosteus plebeius-nebuliferus species-group and sampling localities. The colours correspond to the eight main basins and numbers to the localities: (1) Santa Gertrudis, (2) Arroyo Las Bayas, (3) Pino Suarez, (4) La Barranca, (5) Puente Mimbres, (6) El Cuarto, (7) Peñón Blanco, (8) Covadonga, (9) Arroyo Torreones, (10) El Peñasco, (11) El Olote, (12) Atotonilco, (13) Las Vegas, (14) Fuerte, (15) Oteros, (16) Bocoyna, (17) Conchos, (18) Ureyna, (19) South Fork Palomas Creek, (20) Escalariado, (21) Casas Grandes, (22) Ignacio Zaragoza, (23) Buenaventura and (24) Santa Clara