That doesn't help the fact that you are modifying a global variable ($_) without localizing it first. Why use a global variable at all! 
foreach (@species) {
    ( my $species = $_ ) =~ s/^-//;
    unless (exists $refspecies{$species}) {
        die "$species is not in the species table\n";
    }
}

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In reply to Re^3: Changing array by changing $_? by ikegami
in thread Changing array by changing $_? by johnvandam

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