▁ ▁Classification ▁E . ▁lem nis cat um ▁was ▁described ▁only ▁in ▁ 2 0 0 8 . ▁ ▁It ▁was ▁originally ▁considered ▁a ▁dus ky tail ▁d arter ▁( E . ▁per cn ur um ), ▁but ▁E . ▁per cn ur um ▁was ▁determined ▁a ▁species ▁complex ▁in ▁ 2 0 0 8 ▁by ▁R . E . ▁Bl anton ▁and ▁R . E . ▁Jenkins . ▁ ▁App earance ▁and ▁an atom y ▁It ▁is ▁vis ually ▁distinguished ▁from ▁other ▁species ▁of ▁the ▁E . ▁per cn ur um ▁complex ▁by ▁a ▁more ▁posterior ▁anal ▁fin . ▁ ▁Geographic ▁distribution ▁Origin ally , ▁the ▁t ux edo ▁d arter ▁( then ▁E . ▁per cn ur um ) ▁was ▁reported ▁only ▁in ▁one ▁location ▁of ▁the ▁Big ▁South ▁F ork ▁of ▁the ▁C umber land ▁River , ▁which ▁flows ▁from ▁north - central ▁Tennessee ▁to ▁Mc Cre ary ▁County , ▁Kentucky . ▁ ▁Prior ▁to ▁ 1 9 9 5 , ▁the ▁mouth ▁of ▁Station ▁Camp ▁Creek ▁in ▁Scott ▁County , ▁Tennessee ▁contained ▁the ▁only ▁known ▁t ux edo ▁d arter ▁population . ▁ ▁However , ▁in ▁ 2 0 0 0 ▁D . J . ▁Eisen hour ▁and ▁B . M . ▁B urr ▁discovered ▁six ▁additional ▁sites ▁sp anning ▁nin ete en ▁kilom eters ▁from ▁Station ▁Camp ▁Creek ▁( the ▁original ▁site ) ▁to ▁Bear ▁Creek ▁in ▁Mc Cre ary ▁County , ▁Kentucky . ▁ ▁They ▁estimated ▁the ▁population ▁at ▁ 3 0 0 ▁to ▁ 6 0