File descriptions: Patella_rustica_allozyme_data.txt – file containing information for a set of nine allozyme loci screened through starch gel electrophoresis for samples of Patella rustica Linnaeus, 1758 collected in 13 sampling locations from the Mediterranean and the Iberian and African Atlantic shores. Patella_ulyssiponensis_allozyme_data.txt - file containing information for a set of seven allozyme loci screened through starch gel electrophoresis for samples of Patella ulyssiponensis Gmelin, 1791 collected in 12 sampling locations from the Mediterranean and the Iberian and African Atlantic shores. Data collected by Alexandra Sá Pinto. For questions please contact Alexandra Sá Pinto, Centro de Investigação em Biodiversidade e Recursos Genéticos (CIBIO/UP), Campus Agrário de Vairão, 4485-661 Vairão, Portugal. Telephone: +351 252660414. Fax: +351 252661780. e-mail: xanasapinto@gmail.com Column headings: Patella_rustica_allozyme_data.txt: Species (scientific species name; taxonomic classification based on morphological characters); sampling location (self-explanatory), country (political country of sampling location); voucher (code attributed to each individual sampled); PepD (phenotype obtained for the allozyme Peptidase D, EC: 3.4.13.9); ME (phenotype obtained for the allozyme Malic enzyme, EC: 1.1.1.40), GOT (phenotype obtained for the allozyme Glutamate-oxaloacetate transaminase, EC: 2.6.1.1), GPI (phenotype obtained for the allozyme Glucosephosphate isomerase, EC: 5.3.1.9), MDH (phenotype obtained for the allozyme Malate dehydrogenase, EC : 1.1.1.37), IDH (phenotype obtained for the allozyme Isocitrate dehydrogenase, EC: 1.1.1.42), PGM1 (phenotype obtained for the first locus of the allozyme Phosphoglucomutase, EC: 2.7.5.1), PGM2 (phenotype obtained for the second locus of the allozyme Phosphoglucomutase), PGD (phenotype obtained for the allozyme 6- Phosphogluconate dehydrogenase, EC: 1.1.1.44). Patella_ulyssiponensis_allozyme_data.txt: Species (scientific species name; taxonomic classification based on morphological characters); sampling location (self-explanatory), country (political country of sampling location); voucher (code attributed to each individual sampled); PepD (phenotype obtained for the allozyme Peptidase D, EC: 3.4.13.9); ME (phenotype obtained for the allozyme Malic enzyme, EC: 1.1.1.40), GOT (phenotype obtained for the allozyme Glutamate-oxaloacetate transaminase, EC: 2.6.1.1), GPI (phenotype obtained for the allozyme Glucosephosphate isomerase, EC: 5.3.1.9), MDH (phenotype obtained for the allozyme Malate dehydrogenase, EC : 1.1.1.37), IDH (phenotype obtained for the allozyme Isocitrate dehydrogenase, EC: 1.1.1.42), PGM (phenotype obtained for the allozyme Phosphoglucomutase, EC: 2.7.5.1). Data format and missing data: in both files each allele observed at a given locus is coded by three digits. Individual phenotypes observed at each locus are represented by six digits, coding for the two alleles. Missing data is represented as 000000.