Select2 with incorrect stylization

I'm using a select2, but his style is coming in a way that was not expected. This way:

• HowdoImakeitfitandalignwiththeinput-group?

HTMLcode:

<divclass="form-row">
    <label for="cidade">Cidade</label>
    <div class="input-group">
         <select id="cidade" name="cidade" class="form-control input-bairro"></select>
         <span class="input-group-addon" id="basic-addon3"><i class="icofont icofont-plus"></i></span>
   </div>
    <script type="text/javascript">
      $('#cidade').select2({
          dropdownParent: $('#mdCreateBairros'),
      });
    </script>
</div>

Javascript that starts select2:

$('#cidade').select2({
    dropdownParent: $('#mdCreateRegioes'),
});