EDIT

function palmweb_2_cdm_descriptionElementDistribution($descriptionElements) {

  $descriptions = '';

  $separator = ', ';

  foreach($descriptionElements as $descriptionElement){

    $descriptions .= $descriptionElement->area->representation_L10n . $separator;

  }

  $descriptions = substr($descriptions, 0, strlen($descriptions)-2);

  $taxonTrees =  cdm_ws_get(CDM_WS_TAXONOMY);

  foreach($taxonTrees as $taxonTree){

    if ($taxonTree -> uuid == variable_get('cdm_taxonomictree_uuid', FALSE)){

      $reference = $taxonTree-> reference;

      break;

    }

  }

  $out = substr($out, 0, strlen($out)-strlen($separator) );

  $referenceCitation = '('.l('<span class="reference">World Checklist of Monocotyledons</span>', path_to_reference($reference->uuid), array("class"=>"reference"), NULL, NULL, FALSE ,TRUE).')';

  if($descriptions && strlen($descriptions) > 0 ){

    $sourceRefs .= ' '.$referenceCitation;

  }

  if(strlen($sourceRefs) > 0){

    $sourceRefs = '<span class="sources">' . $sourceRefs . '</span>';

  }

  return $descriptions. $sourceRefs ;

}