After the first finding of Tarebia granifera in September 2007 in Lake Tintal in the Reserva de la Biosfera Pantanos de Centla, a search was conducted in 40 lakes, 6 rivers, 1 stream and two drains: 14 sites from the municipality of Centla, 3 from Centro, 11 from Paraiso, 1 from Nacajuca, 3 from Cardenas, 14 from Jonuta and 3 from Macuspana. Sampling was conducted in September 2008 and May and September 2009. The sampling was random taking 10 samples using five liters Van Veen grab. Tarebia granifera was collected in 11 sites out of 49 in three municipalities: in the town of Centro is was found in L. Pucte and L. La Ceiba; Centla in L. Guanal, L. San Isidro, L. Viento, L. Larga, L. Tintal and L. Concepcion; and Macuspana in L. Loncho, L. Ismate-Chilapilla and L. Chilapa. The polygon of distribution of T. granifera is between the coordinates UTM 509588-590058X and 1989183-1976233 Y (17°59'27.3"-17°52'19.3"Ny92°54'34.0"-92°08'59.7"W).TheCityofVillahermosaisconsideredas an introduction and dispersal center. The localities that presented the highest abundance values were: L. Tintal with a total 7,944 individuals, L. Pucte with 7,048 and L. Ismate-Chilapilla with 1,268. This study confirms the competence between T. granifera and Melanoides tuberculata being the former favored.
