11.   The dorsal arm plates are fan shaped, much wider than long and separated from one another.

12.   The dorsal arm plates are fan to bell shaped not contiguous sometimes with a finely rugose distal edge.

13.   The dorsal arm plates are roundly hexagonal and contiguous proximally.

14.   The dorsal arm plates are triangular and separated.

15.   The dorsal arm plates are wider than long, rectangular and contiguous.

16.   The first ventral arm plate is pentagonal with the lateral edges raised forming a boundary lip to the second oral tentacle pores.

17.   The lateral and ventral arm plates have distinctive transverse ridges most noticeable in dry or nearly dry specimens.

18.   The lateral and ventral arm plates have distinctive transverse ridges most noticeable in dry specimens.

19.   The lateral arm plates also carry a series of long bristle-like spines, dorsal to the arm spines.

20.   The lateral arm plates on the proximal part of the arm are slightly enlarged.