St. Irenaeus after listing Telesphorus as a martyr adds the name of Hyginus.  His name was placed in the Roman Missal in the late Middle Ages; during the first two centuries hardly any of the martyrs had left any trace in the Liturgy.  Their burial places were generally unknown and their worship was local; there was danger that Catholic devotion to the saints might be regarded as a new form of paganism.  Hyginus was a Pope and a martyr (died 142).  Because of the Octave of the Epiphany, his feast is celebrated by a simple commemoration in the Mass Statuit.
(Source: Fr. Lasance, The New Roman Missal)