Taxonomic revision of Steganacarus (Steganacarus) magnus (Nicolet, 1855) (Acarida,Oribatida)

The classical taxon, Steganacarus (Steganacarus) magnus (Nicolet, 1855) is redescribed on the basis of topotypic material. The study and the comparison of many European and North African populations reveals a variation in the size of the anterior notogastral tectum and consequently enables another classic entity, S. (Steganacarus) anomalus (Berlese, 1883), to be put into synonymy. These two different ecophenotypes, in the authors' opinion, seem to be linked to the presence of xeric low-altitude southern environments (S. (S.) magnus f. anomala) or cool higher-altitude mid-northern environments (S. (S.) magnus f. magna).