Specimens with an Artifact Appearing as ‘Three Spines’ in Milnesium tardigradum var. trispinosa Rahm, 1931 (Tardigrada)

Milnesium tardigradum trispinosa Rahm, 1931 is characterized by its three spines at the posterior end of the animal, but has never been reported since its original description. Among mounted specimens of Milnesium sp. from Japan and M. tardigradum s. s. from France, several cases with these ‘three spines’ were observed. In these samples, the character was formed by an artifact of the fixation process. Images of these specimens show such a striking similarity to Milnesium tardigradum trispinosa that this taxon must be considered as having been erroneously established as a result of misinterpretation of an artifact and no longer valid.