Complex sentence: In that classification, the subfamily "Tichodromadinae" contains a single species, the Wallcreeper, and the other subfamily, "Sittinae", contains the 22 species of "true" nuthatches.
Split into simpler sentences: In that classification, the subfamily "Tichodromadinae" contains a single species, the Wallcreeper. The other subfamily, "Sittinae", contains the 22 species of "true" nuthatches.