Figure 2: Male colour phenotypes, calibration plate, and regions on the body and on fins examined in this study. (a) Examples of P. mexicana male colour phenotypes found in the Arroyo Bonita (AB), the El Azufre (EA), and Cueva del Azufre (CA) chambers II, V, and X (from top to bottom). (b) Example of an AB male photographed on the colour calibration plate. (c) Schematic view of the 10 regions for which L*a*b* colour values were determined. The size of the squares represents 1/35 of the individual male’s standard length.