1.   The distal ventral arm plates are more pentagonal with an obtuse proximal angle and a wide convex distal edge.

2.   The dorsal arm plates are fan shaped with an acute proximal angle and separated.

3.   The oral shield is rhombic but often with an obtuse proximal angle and a convex distal edge.

4.   The oral shields is a rounded pentagonal with an obtuse or slightly rounded proximal angle.

5.   The ventral arm plates are pentagonal with an acute proximal angle, a slightly indented distal edge, and separated from one another.

6.   The ventral arm plates are wider than long, pentagonal with an obtuse proximal angle and a slightly convex distal edge.