Nasopharyngeal mites Halarachne halichoeri (Allman, 1847) parasitizing the gray seal Halichoerus grypus (Fabricius, 1791) in the Baltic Sea with notes on other parasitic Halarachnidae associated with marine mammals

Parasitic arthropods of marine mammals are relatively poorly understood, with the least amount of data on the occurrence of parasitic arthropods in these hosts. Thus far, only seal lice Echinophthirius horridus (von Olfers, 1816) have been found in the Baltic seals, while there was no information about the presence of parasitic mites in these mammals. The nasopharyngeal mite Halarachne halichoeri (Allman, 1847) has recently been found in the gray seal Halichoerus grypus (Fabricius, 1791), representing a new species (and new genus) for the Polish fauna. Sixty three specimens were found in the nasal cavity and the trachea, including 18 females and 45 males. This is also the first documented record of Halarachnidae in seals of the Baltic Sea. A checklist of parasitic Halarachnidae known from marine mammals is also provided.