query: SELECT ?taxon ?taxonLabel ?de ?en ?fr ?nl  WHERE {
  bind(if(bound(?english), "+", "-") as ?en )
  bind(if(bound(?french), "+", "-") as ?fr )
  bind(if(bound(?dutch), "+", "-") as ?nl )
  bind(if(bound(?german), "+", "-") as ?de )
  {SELECT ?taxon ?taxonLabel ?english ?french ?dutch ?german WHERE {
     wd:Q3052500 wdt:P1990 ?taxon .
     OPTIONAL {?english schema:about ?taxon .
     FILTER (regex(str(?english), "https://en.wikipedia"))}
     OPTIONAL {?dutch schema:about ?taxon .
     FILTER (regex(str(?dutch), "https://nl.wikipedia"))}
     OPTIONAL {?french schema:about ?taxon .
     FILTER (regex(str(?french), "https://fr.wikipedia"))}
     OPTIONAL {?german schema:about ?taxon .
     FILTER (regex(str(?german), "https://de.wikipedia"))}
  SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
  }}}