Dicas

<?php
  if( is_single() ) {
    global $post;
    $categories = get_the_category();
    $category = $categories[0];
  } else {
    $category = $wp_query->get_queried_object();
  }
  $parent = ($category->category_parent)? $category->category_parent :$category->3;
?>
<ul>
  <?php
    global $post;
   $myposts = get_posts('numberposts=50&category='.$category->3.'');

  foreach($myposts as $post) :
  ?>
  <li>
    <a href="<?php the_permalink(); ?>">
      <?php the_title(); ?>
    </a>
  </li>
  <?php endforeach; ?>
</ul>