$c='[\d\-\.pqxy]'; #regexp
(@chroms)=($text=~/\s$c*?\s/sig); #extract all
for ($i=0; $i<@chroms; $i++) {
splice(@chroms, $i, 1) if (!($chroms[$i]=~/[pqxy]/i));
} #eliminate pure numbers
print "$_\n" foreach (@chroms);