List of populations sampled. Accession numbers of sequences refer to GenBank codes. G = number of specimens used for genetics analyses. a The suffixes “o” and “x” indicate the presence and the absence of the eye pigment, respectively. b The codes KFo and TJx here substitute ICo and SVx in Casu and Curini-Galletti (2004), respectively. c Sibling codes used in Casu and Curini-Galletti (2004). d Abbreviation “Br” and “Ma” indicate brackish-water and marine populations, respectively. e Superscript codes refer to the specific analysis applied to individuals: M = morphology; K = karyology; R = reproductive biology; G = genetics. Accession numbers of newly sequenced taxa are in bold.