Complex sentence: Historically, up to 1973, "Trichodorus" was placed in a subfamily, as its only genus, the Trichodorinae Thorne 1935, within the family Diphtherophoridae, to distinguish it from the other subfamily, Diphtherophorinae.
Split into simpler sentences: Historically, up to 1973, "Trichodorus" was the only genus in this family. Originally it was the only genus in a subfamily, the Trichodorinae Thorne 1935, within the family Diphtherophoridae, to distinguish it from the other subfamily, Diphtherophorinae.