Sources and Uncertainties
The available sources differ on the basic circumstances of Dioscorus's martyrdom. The English Wikipedia list of May 11 commemorations identifies him as "Dioscorus (Dioscorides) the New, of Smyrna" and records that he died by beheading, without assigning a year. The OrthodoxWiki calendar instead places him at Thessalonica and pairs him with a companion martyr, Argyrus, giving an approximate date of 1806 or 1808.
The point on which the sources converge is that Dioscorus was a New Martyr of the Ottoman period who was put to death for refusing to abandon his Christian confession. His liturgical hymns dwell on this steadfastness, describing him as having received "an incorruptible crown" through his sufferings and as having resisted the pressures of the world and of false religion. The conflicting place and date should be treated with caution pending review against a primary synaxarion. This figure is distinct from the early Martyr Dioscorus commemorated on October 13, who suffered under Diocletian.