Ilyocryptus sarsi Stingelin, 1913

Ovoid body, dorsal keel present but not developed, molting incomplete; setae on the posterior margin of valves with inflated base and armed with a slender and sharp spine, setulae present. Head triangular, ovoid or semi-ovoid, fornices prominent; postabdomen relatively short, preanal and postanal part of similar length; anal margin short with 6-9 setulae inserted laterally; marginal denticles of preanal part with regular morphology, relatively long; 17-20 marginal spines, of which median ones have similar length; 5-7 lateral setae markedly longer than marginal spines;“gap” between proximalmost lateral seta and anal margin not developed; basal spines on the postabdominal claw of different length.

Comments: Ilyocryptus sarsi was treated in Elmoor-Loureiro (1997) as Ilyocryptus sordidus Liévin, 1848, a species with Palearctic distribution. However, Kotov et al. (2001) found a significant number of differences between these two species. In spite of the low number of records (Fig. 3F), Ilyocryptus sarsi has a broad occurrence range in Brazil.