Richness and diversity of aquatic insects in the Usumacinta River basin in Mexico

Aquatic insects play an important role in aquatic ecosystem but little is known about their diversity, distribution and ecology in the Usumacinta River Basin. The objective was to analyze richness and diversity patterns of aquatic insect assemblages in the Usumacinta Basin in Mexico. Entomological collections and literature were revised for reported taxa for the Usumacinta watershed. Sampling was conducted in streams, rivers, and floodplain lakes in Centla, Tenosique-Palizada and Lacantim-Yaxchilan. The number of families was increased from 45 to 70 and the number of genera from 109 to 192. The Lacantnn-Yaxchilan area showed the highest richness, with 70 genera, followed by Centla with 69 and Tenosique-Palizada with 62. Ephemeroptera and Trichoptera were very abundant and diverse in the lotic habitats of Lacantim-Yaxchilan, while Diptera, Hemiptera and Odonata dominated in the lentic habitats of Centla and Tenosique-Palizada. Abundance was lower during the rainy season in the three study areas. The highest diversity was associated to streams and rivers in Lacantan-Yaxchilan and a floodplain lake in Centla with abundant aquatic macrophytes, suggesting that habitats with greater diversity can occur at different points along the basin, including the lotic environments of the tributaries and in lakes of the Usumacinta floodplain.