1994  Pennoceras sp.nov.1 Boardman, Work, Mapes & Barrick: 62, pl.3 fig.15-17. [not pl.3 fig.18-20, = P. heckeli)
          2007  Pennoceras bennisoni  Work, Boardman & Mapes: 595, fig.3.7, 3.8, 5, 6.

Nos. SUI 55436, Iowa City.