Protolophus singularis Banks, 1893 - USA - from flickr. Copyright © M Hedin [Marshal Hedin]]].
Initially described by Banks (1893) as a tribe, Protolophini, in Phalangiidae.
Later, Roewer (1911) transferred the type and only genus (Protolophus) to the subfamily Leptobunini (Roewer, 1923, corrected the ending to Leptobuninae), where it remained until the subfamily was dismantled by Cokendolpher (1985). He suggested raising the group to subfamily status and emended the ending to Protolophinae within the family Gagrellidae. Edgar (1990) listed the genus in the Sclerosomatidae, and Crawford (1992) retained the group at the subfamily level within an unspecified family, but remarked that the group may be justified as a family. Cokendolpher and Lee (1993) raised the group to family status and recognized only the single monogeneric subfamily Protolophinae. (Cokendolpher et al., 2007).