| abstract | The Piauí State, Brazil, has never had its chigger fauna recorded. In this study, we examined chiggers collected on marsupials, rodents, and lizards from the conservation unit Parque Nacional da Serra das Confusões (PNSC). Herein we describe four new species, Paraguacarus klompeni n. sp., Neoschoengastia ochoai n. sp., Quadraseta welbourni n. sp., and Susa bauchani n. sp. Furthermore, an additional seven species are reported: Eutrombicula alfreddugesi (Oudemans, 1910), Microtrombicula brachytrichia Brennan, 1971, Microtrombicula rhipidomysi Goff, Whitaker and Dietz, 1983, Parascoschoengastia aemulata (Brennan and Jones, 1964), Parasecia valida Brennan, 1969, Pseudochoengastia petrolinensis Jacinavicius, Bassini-Silva and Barros-Battesti 2019, and Quadraseta flochi (Brennan and Jones, 1960). This is the first report of chiggers in Piauí State, which includes one of the most biodiverse areas in the Caatinga biome and is of particular importance to conservation. The genera Paraguacarus Goff and Whitaker, 1984 and Susa Audy and Nadcharam, 1960 are reported here for the first time to Brazil. |