Key to the Species of Pteronotropis

3a. (From 2b.) Predorsal scales usually 17 to 22, usually 19 or 20; membranes of median 4 to 5 caudal rays pigmented; basicaudal spot continuous with lateral stripe; edge of dorsal fin usually straight.

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3b. (From 2b.) Predorsal scales usually 22 to 24; membranes of median 4 to 5 caudal rays clear, forming a "window;" basicaudal spot vertical to chevron-shaped and separate from lateral stripe; edge of dorsal fin usually convex.

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