Twenty seven species of Trombidiidae have been recorded from Poland. Nine of them are known from larvae and postlarval instars, fourteen – exclusively from postlarval forms, four – only from larvae. Descriptions are provided with figures, distribution maps and tabulated metric characters.
The following new synonyms are proposed: Sericothrombium brevimanum Berlese, 1910 (= Trombidium rowmundi Haitlinger, 1996), Acarus holosericeus L. (= Trombidium poriceps Oudemans, 1904), Trombidium rimosum C. L. Koch, 1837 (= Trombidium meyeri Krausse, 1916), Trombidium megalochirum Berlese, 1910 (= Dinothrombium rubropurpureum Oudemans, 1914), Trombidium filipes C. L. Koch, 1837 (= Podothrombium magnum Berlese, 1910, = Podothrombium proti Haitlinger, 1994, = Podothrombium roari Haitlinger, 2000), Podothrombium kordulae Haitlinger, 1995 (= Podothrombium rigobertae Haitlinger, 1995), Podothrombium verae Haitlinger, 1995 (= Podothrombium tersonderi Haitlinger, 1995). Neotypes are designated for Trombidium rimosum C. L. Koch, 1837, Trombidium fuliginosum Hermann, 1804, Trombidium molliculum C. L. Koch, 1837 and Trombidium bicolor Hermann, 1804, whereas lectotypes – for Allothrombium wolmari Haitlinger, 2000, Podothrombium macrocarpum Berlese, 1910 and Podothrombium strandi Berlese, 1910. Sericothrombium carpaticum Feider, 1950, Trombidium fuornum Schweizer, 1951 and Trombidium susteri Feider, 1956 are treated as doubtful taxa. The specific status of Allothrombium lechi Haitlinger, 1996 (syn. of Trombidium fuliginosum Hermann, 1804 [?]) and Podothrombium dariae Haitlinger, 1995 is also regarded as doubtful because of insufficiently indicated differentiating characters and the poor condition of type specimens, which do not allow a critical reappraisal of the types.
Trombidium latum C. L. Koch, 1837, Trombidium monticola sp. nov., Podothrombium macrocarpum Berlese, 1910, Podothrombium spinosum Feider, 1955 and Podothrombium strandi Berlese, 1910 are new to the Polish fauna. Allothrombium meridionale Berlese, 1910 and Allothrombium pergrande Berlese, 1903 should be excluded from the checklist of trombidiids of Poland due to misidentifications confirmed after studies of the type material in the Berlese Acaroteca.