Shifter = instant army

[Shard O'Glase]

So a wizard or cleric needs to have seen a fiendish shark, to summon one?

No but the wizard or cleric should of seen or at least know about sharks before they can summon a fiendish version of one. I'm not sure I'd require actually seeing one to summon, learning enough about one would be enough for me. Note by the rules you aren't limited by knowledge or seeing things for either wildshape or summoning. Many dms do think it is a logical rule though.

 

[(Psi)SeveredHead]

A wizard could find out about fiendish dire apes by visiting a library of magic. So could a druid... oh wait, that means Speaks with Stone would actually have to enter a city to do so.