• Monothrix Ogilby, 1897
• Monothrix Torr. accepted as Perityle Benth.
• Monothrix congesta (M.E.Jones) Rydb. accepted as Perityle congesta (M.E.Jones) Shinners
• Monothrix fastigiata (Brandegee) Rydb. (uncertain > unassessed)
• Monothrix intricata (Brandegee) Rydb. accepted as Perityle intricata (Brandegee) Shinners
• Monothrix megalocephala (S.Watson) Rydb. accepted as Perityle megalocephala (S.Watson) J.F.Macbr.
• Monothrix megalocephala Rydb. (uncertain > unassessed)
• Monothrix mizolepis (Günther, 1867) accepted as Didymothallus mizolepis (Günther, 1867)
• Monothrix palmeri (A.Gray) Rydb. (uncertain > unassessed)
• Monothrix polylepis Ogilby, 1897
• Monothrix stansburyana Torr. (uncertain > unassessed)
• Monothrix stansburyi (A.Gray) Rydb. accepted as Perityle stansburyi (A.Gray) J.F.Macbr.
• Monothrix toumeyi (B.L.Rob. & Greenm.) Rydb. (uncertain > unassessed)