The first record of an unknown Coccidea Leuckart, 1879 in the midgut of trombiculid larvae Hirsutiella zachvatkini (Acariformes, Trombiculidae)

For the first time, unknown protists were found in the midgut of larvae Hirsutiella zachvatkini (Schluger, 1948) (Trombiculidae), feeding on a bank vole Clethrionomys glareolus in the Pskovskaya Oblast (Russia). The same protozoans were also identified in the tissues of the vole. Generally, these cells were spindle-shaped, around 4 µm in length, exhibiting a violet cytoplasm and a blue centrally located elongated nucleus, as highlighted by staining. Most probably, these cells represent one of the Babesia (Piroplasmida) species in a single-cell stage (e. g., sporozoites), which got into the vole accidentally as a result of a possible tick bite. Alternatively, these cells represent one of the Toxoplasma (Eimeriida) species in the individual cell form (e. g., tachyzoites or sporozoites) that may be encountered in other animals. However, a single instance of the presence of protozoans in trombiculid larvae may suggest that (i) the circulation of protozoans among the population of voles or trombiculids in northwestern Russia is highly restricted and is not of an epidemiological importance and (ii) this path of infection is blind and may cause the subsequent death of both the larva and the protists.