northern brown howler
... that no more than 50 mature individuals of the critically endangered northern brown howler are estimated to remain?
... that no more than 50 mature individuals of the <a href="./Critically_Endangered" id="mwBeU" rel="mw:WikiLink" title="Critically Endangered">critically endangered</a> <b id="mwBeY"><a href="./Northern_brown_howler" id="mwBec" rel="mw:WikiLink" title="Northern brown howler">northern brown howler</a></b> are estimated to remain?