Xenurobrycon varii can be easily distinguished from its congeners by the dark posterior half of both caudal-fin lobes (vs. hyaline) and the lack of infraorbitals 4 and 5 (vs. absence of infraobitals 1, 4 and 5 in X. coracoralinae and presence of infraorbitals 1-5 in X. heterodon, X. macropus, X. polyancistrus and X. pteropus). It further differs from other species of Xenurobrycon , except X. coracoralinae and X. macropus, by having a set of lamellar processes on the eighth principal ray of the lower caudal-fin lobe (vs. absence in X. heterodon, X. polyancistrus and X. pteropus). It can be diagnosed from X. coracoralinae by having hooks on the last unbranched plus the first 9th-12th branched anal-fin rays of mature males (vs. hooks present only on last unbranched and first 4th-5th branched rays). In addition, it can be distinguished from X. heterodon by having only conical dentary teeth (vs. anterior dentary teeth tricuspid). It differs also from X. polyancistrus by the posterior anal-fin hooks approximately equal or reduced in size posteriorly in mature males (vs. posterior larger anal-fin hooks). It can be further differentiated from X. pteropus by the absence of adipose-fin (vs. presence) and by having 15-18 predorsal scales (vs. 13) (Ref. 109914).