COMPOSITION AND DISTRIBUTION OF CONTINENT AL FISHES IN SOUTHERN QUINTANA-ROO, YUCATAN PENINSULA, MEXICO

Composition and distribution of the continental ichthyofauna were stud ied in southern Quintana Roo and adyacent areas of Campeche and Belize , southeastern Yucatan Peninsula, Mexico, on the basis of 69 sampled l ocalities, as well as the published information and the fish collectio n carried out by the Zoology Museum at the Quintana Roo Research Cente r (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 recorde d parameters such as temperature, salinity and conductivity, transpare ncy, depth, dissolved oxygen, bottom type and riparian vegetation. Mos t of the sites were visited in the rainy and the dry seasons. The inve ntory of continental fishes of Quintana Roo includes 85 species, 55 de tected 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, Eu gerres plumieri, Stegastes leucostictus, Rivulus tenuis., Phallichthys fairweatheri, Xiphophorus helleri, and Stephonolepis hispidus. Cluste r analysis allowed distinction of the following four local ichthyofaun as, sorted by decreasing distance to the coast: (1) Zohlaguna Plateau, some 250 masl, with relatively cool waters; (2) Hondo River and borde ring water bodies, such as freshwater cenotes, wetlands, pools and cre eks; (3) Center-Northeast Zone, including the brackish lake systems of Bacalar, Guerrero and Ubero, as well as the wetlands around the Bay o f Chetumal and freshwater lakes such as Vallehermoso; and (4) Southern Caribbean coastal lagoons, where salinity varies regularly. Ichthyofa una (I) is characterized by the occurrence of X. helleri and Rhamdia g uatemalensis and the frequency of Heterandria bimaculata and Poecilia petenensis; (2), by the frequency of primary fishes such as Hyphessobr ycon compressus and Rhamdia laticauda, as well as Ophisternon aenigmat icum; (3) by peripheral fishes, such as Arius assimilis, Gobiomorus do rmitor and Anchoa colonensis; (4), by a significatively greater richne ss, due to the dominance of marine fishes of the families Gerreidae, L utjanidae, and others, which utilize mangroves as nursery or feeding g rounds. Even though the fish distribution within the study area follow s essentially ecological factors, the decrease in neotropical or prima ry fishes from Belize to Sian Ka'an shows the importance of historical factors on a slightly larger geographical scale.