Elmidae (Coleoptera, Byrrhoidea) larvae in the state of São Paulo, Brazil: Identification key, new records and distribution

The family Elmidae Curtis, 1830 has cosmopolitan distribution and most species inhabit riffles on streams and rivers, hence the name "riffle beetle". In recent years, this family has been featured in papers addressing the assessment and environmental monitoring of water quality. In Brazil, studies on the family remain scarce and the present investigation is a pioneering study in the state of São Paulo. This study aims to propose a taxonomic key for the identification of larvae of Elmidae genera known to occur in the State, as well as to report new records and the distribution of these genera. The material analyzed was collected from various locations in each of 15 drainage basins from 2005 to 2010. The identification key includes 12 genera (Austrolimnius Carter & Zeck, 1929, Heterelmis Sharp, 1882, Hexacylloepus Hinton, 1940, Hexanchorus Sharp, 1882, Huleechius Brown, 1981, Macrelmis Motschulsky, 1859, Microcylloepus Hinton, 1935, Neoelmis Musgrave, 1935, Phanocerus Sharp, 1882, Potamophilops Grouvelle, 1896, Stegoelmis Hinton, 1939 and Xenelmis Hinton, 1936) known in Brazil as well as three morphotypes designated herein as Genus A, Genus M and Genus X. The genus Hexanchorus is recorded for the first time in the state of São Paulo.