Custom taxonomy in short code

Not sure if is this, but you can add taxonomies in query:

new WP_Query(array('posts_per_page' => $num, 'post_status' => 'publish','taxonomy' => $taxonomy)); 

You can filter by term with $taxonomy => $term:

$taxonomy = 'seasons';
$term = 'spring'
/* $terms = array('summer','winter')  an array */

new WP_Query(array('posts_per_page' => $num, 'post_status' => 'publish',$taxonomy => $term)); 

More on WP_Query

Note: taxonomies and terms are not the same thing 🙂