Map of the El Abra region, showing the five biogeographic zones proposed by Kopp et al. (2018) and supported by both Astyanax and mysids in this study: Sierra de Guatemala (yellow), Northern Sierra de El Abra (Red), Central Sierra de El Abra (blue), Southern Sierra de El Abra (Black), and Micos (green). A Pachón cave B Refugio Cave. Before this study, Pachón was the only known cave to harbor cavefish in the northern Sierra de El Abra. Map modified from Mitchell at al. (1977).