arteleku_drupal_module/plugins/layouts/tarjeta/tarjeta.inc

<?php

$plugin = array(
   'title' => t('Layout tarjeta'),
   'icon' => 'tarjeta.png',
   'theme' => 'arteleku_tarjeta',
   'css' => 'tarjeta.css',
   'regions' => array(
    'contenido' => t('Contenido'),
   ),
 );