EDIT

  $taxon_tabs_weights = get_array_variable_merged(CDM_TAXONPAGE_TAB_WEIGHT, CDM_TAXONPAGE_TAB_WEIGHT_DEFAULT);

  $form['taxon_tabs'][CDM_TAXONPAGE_TAB_WEIGHT] = array(

    '#title'  => 'Tabs order',

    '#tree' => true,

    '#description' => 'The weight value defines the order of the tabs or of the respective content block on the 

        taxon page when it is the tabless mode.'

  $taxon_tabs_labels = get_array_variable_merged(CDM_TAXONPAGE_TAB_LABELS, CDM_TAXONPAGE_TAB_LABELS_DEFAULT);

  $form['taxon_tabs'][CDM_TAXONPAGE_TAB_LABELS] = array(

    '#title'  => 'Tab label override',

    '#tree' => true,

    '#description' => 'Setting a label for a tab will override the default label.'

  );