Having trouble putting SPAN tags in primary links menu

Drupal 7:

Here is what I have so far:

function alphanews_links__system_main_menu($variables) {
  $output = '';
  foreach ($variables['links'] as $link) {
  	if (empty($link['localized_options'])) {
	    $link['localized_options'] = array();
	}
  	$link['localized_options']['html'] = TRUE;
    $output .= l('<span>'. $link['title'] .'</span>', $link['href'], $link['localized_options']);
  }
  return $output;
}

This is putting the links inside span tags, but I lost the ul and li tags for the list.

Thanks.