>perl -wMstrict -le
"use List::Util qw(first);
 my %gg = (
   1567 => [ qw(NP_011  NP_012  NP_013  NP_025)         ],
   2000 => [ qw(NP_020  NP_021  NP_024  NP_025  NP_035) ],
   9999 => [ qw(NP_900  NP_910  NP_902  0)              ],
   9998 => [],
   );
 SEARCH:
 for my $gene_to_find (qw(NP_011  NP_025  NP_999  0)) {
   print qq{searching for gene '$gene_to_find':};
   my $matching_taxon =
     first { defined first { $_ eq $gene_to_find } @{ $gg{$_} } }
     keys %gg
     ;
   my @all_matching_taxons =
     grep { defined first { $_ eq $gene_to_find } @{ $gg{$_} } }
     keys %gg
     ;
   print qq{  NOT found} and next SEARCH if not $matching_taxon;
   print qq{  first found: '$matching_taxon'};
   my $all_found = join q{' '}, @all_matching_taxons;
   print qq{  all found: '$all_found'};
   }
"
searching for gene 'NP_011':
  first found: '1567'
  all found: '1567'
searching for gene 'NP_025':
  first found: '2000'
  all found: '2000' '1567'
searching for gene 'NP_999':
  NOT found
searching for gene '0':
  first found: '9999'
  all found: '9999'