EDIT

            if(taxonName.getNomenclaturalReference() != null){

                Reference nomRef = taxonName.getNomenclaturalReference();

                //getView().getNomReferenceCombobox().setEnabled(nomRef.isOfType(ReferenceType.Section));

                publishedUnit = nomRef;

                while(publishedUnit.isOfType(ReferenceType.Section) && publishedUnit.getInReference() != null){

                    publishedUnit = nomRef.getInReference();

                }

                // reduce available references to those which are sections of the publishedUnit and the publishedUnit itself

                // nomReferencePagingProvider

                nomReferencePagingProvider.getCriteria().add(Restrictions.or(

                        Restrictions.and(Restrictions.eq("inReference", publishedUnit), Restrictions.eq("type", ReferenceType.Section)),

                        Restrictions.idEq(publishedUnit.getId())

                        )

                );

                // and remove the empty option

                getView().getNomReferenceCombobox().getSelect().setNullSelectionAllowed(false);

                // new Reference only a sub sections of the publishedUnit

                newReferenceInstantiator = new BeanInstantiator<Reference>() {

                    @Override

                    public Reference createNewBean() {

                        Reference newRef = ReferenceFactory.newSection();

                        newRef.setInReference(publishedUnit);

                        return newRef;

                    }

                };