#old snippet
   if (exists ( $genus {$hit[2]})) {   
       $genus{$hit[2]}++;                 
   }   else{                                        
           $genus{$hit[2]} = 1;           
   }

##</code><code>##

#new snippet
$genus{ $hit[2] }++

##</code><code>##

%genus = { } ; #genus is empty
$genus{ foo }; #requests foo entry, and throws away.
                      #genus is now { foo => undef }
$genus{ foo } ++; # genus is now { foo => 1 }