my $aref = $matches{ $fasta_id }{ $sitekey };
my( $lo, $hi ) = ( 0, scalar @{ $aref } );
++$lo while ($aref->[ $lo + 1 ] < $lowerlimit && $lo < $hi-2);
 --$hi while ($aref->[ $hi - 1 ] > $upperlimit && $hi > 0  );