What classification issue arises when comparing South American knifefish to African and Asian knifefish?

Answer

The name applies to groups that have converged on a similar body plan but are not closely related taxonomically.

The term 'knifefish' is a common name applied to groups that independently evolved a similar body plan, indicating superficial similarity rather than strict monophyletic ancestry.

What classification issue arises when comparing South American knifefish to African and Asian knifefish?
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