1. Species Pachymelon amoriaformis (Marwick, 1926) †
2. Subgenus Pachymelon (Palomelon) H. J. Finlay, 1926 accepted as Alcithoe H. Adams & A. Adams, 1853 (junior subjective synonym)
   1. Species Pachymelon (Palomelon) benthicola Dell, 1963 accepted as Alcithoe benthicola (Dell, 1963) (superseded combination)
   2. Species Pachymelon (Palomelon) fissurata Dell, 1963 accepted as Alcithoe fissurata (Dell, 1963) (superseded combination)
   3. Species Pachymelon (Palomelon) grahami A. W. B. Powell, 1965 accepted as Alcithoe wilsonae (A. W. B. Powell, 1933) (junior subjective synonym)
   4. Species Pachymelon (Palomelon) powelli Laws, 1936 † accepted as Alcithoe powelli (Laws, 1936) † (superseded combination)
   5. Species Pachymelon (Palomelon) smithi A. W. B. Powell, 1950 accepted as Alcithoe wilsonae (A. W. B. Powell, 1933) (junior subjective synonym)
   6. Species Pachymelon (Palomelon) suropsilos Stilwell & Zinsmeister, 1992 † accepted as Adelomelon suropsilos (Stilwell & Zinsmeister, 1992) † (superseded combination)
   7. Species Pachymelon (Palomelon) wilsonae A. W. B. Powell, 1933 accepted as Alcithoe wilsonae (A. W. B. Powell, 1933) (superseded combination)
3. Species Pachymelon bartrumi L. C. King, 1933 † accepted as Alcithoe bartrumi (L. C. King, 1933) † (superseded combination)
4. Species Pachymelon callaghani L. C. King, 1931 † accepted as Alcithoe callaghani (L. C. King, 1931) † (superseded combination)
5. Species Pachymelon powelli Laws, 1936 † accepted as Alcithoe powelli (Laws, 1936) † (superseded combination)
6. Species Pachymelon uptonensis L. C. King, 1934 † accepted as Alcithoe uptonensis (L. C. King, 1934) † (superseded combination)

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