How to tell S. punctifer from S. frontosus?

[Chrysichthys]

LFS has a syno which appears to be one or the other of these, but looking at the Cat-eLog pics, I can't decide which. No info on what it is supposed to be, it's a contaminant in a batch of nigritas. I'll take some pics next time I'm there.

[Silurus]

The pictures in Poll will indicate that they are two different-looking fish. Synodontis punctifer has filamentous extensions to the dorsal and pectoral spines (which S. frontosus lacks) and its branches on the mandibular barbels are more prominent.

[Chrysichthys]

That would seem to make it a frontosus; but the frontosus in the first Cat-eLog thumbnail has a short dorsal extension. Unfortunately I don't have access to Poll's book, to be able to compare the two.

Tomorrow I'll go to the LFS and see if I can get some pics. It's possible that it might not be either of the two.