Composition and distribution of continental fishes in southern Quintana Roo, Yucatan Peninsula, Mexico

Composition and distribution of the continental ichthyofauna were studied in southern Quintana Roo and adyacent areas of Campeche and Belize, southeastern Yucatan Peninsula, Mexico, on the basis of 69 sampled localities, as well as the published information and the fish collection carried out by the Zoology Museum at the Quintana Roo Research Center (MZ-CIQRO P). Fishing gear included 2- and 20-m-long seine nets, 1- and 3-m-wide throw nets, hook, spear, hand nets, and traps; we recorded parameters such as temperature, salinity and conductivity, transparency, depth, dissolved oxygen, bottom type and riparian vegetation. Most of the sites were visited in the rainy and the dry seasons. The inventory of continental fishes of Quintana Roo includes 85 species, 55 detected in the southern zone. Twelve are recorded for the first time in continental waters of the state: Anchoa colonensis, A. parva, Rhamdia laticauda, Atherinella sp., Strongylura timucu, Diapterus auratus, Eugerres plumieri, Stegastes leucostictus, Rivulus tenuis., Phallichthys fairweatheri, Xiphophorus helleri, and Stephonolepis hispidus. Cluster analysis allowed distinction of the following four local ichthyofaunas, sorted by decreasing distance to the coast: (1) Zohlaguna Plateau, some 250 masl, with relatively cool waters; (2) Hondo River and bordering water bodies, such as freshwater cenotes, wetlands, pools and creeks; (3) Center-Northeast Zone, including the brackish lake systems of Bacalar, Guerrero and Ubero, as well as the wetlands around the Bay of Chetumal and freshwater lakes such as Vallehermoso; and (4) Southern Caribbean coastal lagoons, where salinity varies regularly. Ichthyofauna (I) is characterized by the occurrence of X. helleri and Rhamdia guatemalensis and the frequency of Heterandria bimaculata and Poecilia petenensis; (2), by the frequency of primary fishes such as Hyphessobrycon compressus and Rhamdia laticauda, as well as Ophisternon aenigmaticum; (3) by peripheral fishes, such as Arius assimilis, Gobiomorus dormitor and Anchoa colonensis; (4), by a significatively greater richness, due to the dominance of marine fishes of the families Gerreidae, Lutjanidae, and others, which utilize mangroves as nursery or feeding grounds. Even though the fish distribution within the study area follows essentially ecological factors, the decrease in neotropical or primary fishes from Belize to Sian Ka'an shows the importance of historical factors on a slightly larger geographical scale.