A New Species of the Feather Mite Genus Grallolichus Gaud, 1960 (Acariformes: Pterolichidae): First Report of a Commensal Mite Specific to the Sungrebe (Heliornis fulica)

Feather mites of finfoots (Heliornithidae), a small gruiform family, are poorly and partly erroneously recognized. <i>Grallolichus heliornisi</i> sp. n. (Astigmata: Pterolichidae) is here described from the sungrebe <i>Heliornis fulica</i> as the first representative of the genus commonly found on close relatives of finfoots, Rallidae and Sarothuridae. This species belongs to the species group having ornamented dorsal shields and is morphologically most close to <i>G. proctogamus</i> inhabiting Eurasian coot (<i>Fulica atra</i>). Males of the new species differ from <i>G. proctogamus</i> mainly by the shape of opisthosomal lobes (triangular vs. rounded) and the aedeagus form (parallel sided vs. tapering distally). Females differ mainly by the shape of supranal concavity (open anteriorly vs. closed) and location of setae <i>h1</i> in relation to supranal concavity (lateral vs. anterior). A key to known species of the genus <i>Grallolichus</i> is provided. The morphological analysis and descriptive characterization of this species, like much of the approximately 2500 feather mite species described to date, were based on mummified mite material preserved in 19th-century old museum bird specimens. These often-forgotten collections are the only source for the analysis of the acarofauna of many rare, unavailable wild or even extinct bird taxa.