#!/usr/bin/perl -w

use strict;

my $dir     = '/some/dir';
my $file_re = qr/^(?:\.+|[a-zA-Z]{4}-[0-9]{8})$/;

opendir(DIR, $dir) or die "opening $dir: $!\n";

for ( grep(!/$file_re/, readdir(DIR)) ) {
# deal with non conforming file names here
}
closedir(DIR);