Specimens of newly discovered populations of hypogean Rhamdia from Chiapas, showing observable external morphological features, including variation in the degree of troglomorphism (eye reduction and depigmentation) a preserved specimens of R. laticauda from Paso Burro cave b preserved specimens of R. laticauda from El Chorro Grande cave c preserved specimens of R. guatemalensis from Los Bordos cave d preserved specimen of R. guatemalensis from El Encanto cave e fresh specimen (prior to euthanasia and formalin fixation of R. laticauda from Paso Burro cave in lateral (body, both sides) and dorsal (head) views, displaying partial troglomorphism characterized by depigmentation and complete absence of the right eye f fresh specimens of R. guatemalensis from Los Bordos cave, displaying a wide spectrum of variation in the degree of troglomorphism, including complete loss of eyes and pigmentation.