om ys ▁is ▁by ▁far ▁the ▁biggest ▁and ▁most ▁extensive ▁genus , ▁containing ▁small , ▁incon sp ic uous ▁wood ▁m ice ▁which ▁are ▁common ▁to ▁the ▁whole ▁of ▁the ▁Philippines , ▁while ▁the ▁other , ▁more ▁special ized ▁gener a ▁are ▁bare ly ▁ever ▁found ▁outside ▁Lu zon . ▁Ap om ys ▁itself ▁was ▁divided ▁in ▁two ▁groups ▁by ▁American ▁bi ologist ▁Guy ▁Mus ser ▁in ▁ 1 9 8 2 , ▁the ▁first ▁being ▁the ▁data e ▁group , ▁containing ▁only ▁the ▁Lu zon ▁mont ane ▁forest ▁mouse ▁( A . ▁data e ), ▁and ▁the ▁second ▁the ▁ab ra e - hy loc etes ▁group , ▁containing ▁all ▁other ▁species . ▁Anim als ▁in ▁these ▁two ▁groups ▁differ ▁in ▁the ▁way ▁in ▁which ▁the ▁head ▁is ▁supplied ▁with ▁blood ▁from ▁ar ter ies . ▁R ued as ▁placed ▁the ▁large ▁Mind iro ▁forest ▁mouse ▁in ▁the ▁data e ▁group . ▁This ▁relationship ▁is ▁further ▁supported ▁by ▁other ▁similar ities : ▁both ▁species ▁are ▁relatively ▁large ▁for ▁the ▁genus ▁and ▁have ▁a ▁relatively ▁long ▁sn out . ▁ ▁In ▁ 2 0 0 3 , ▁a ▁ph y log en etic ▁study ▁was ▁published ▁which ▁compared ▁DNA ▁sequences ▁from ▁the ▁cy to chrome ▁b ▁gene ▁of ▁th ir teen ▁species ▁of ▁Ap om ys . ▁This ▁study ▁confirmed ▁the ▁proposed ▁relationship ▁between ▁the ▁large ▁Mind oro ▁forest ▁mouse ▁( A . ▁g rac ili ro str is ) ▁and ▁the ▁Lu zon ▁mont ane ▁forest ▁mouse ▁( A . ▁data e