Abstract: This paper describes a new species of the genus Ochotona (Ochotonidae,Lagomorpha) from Pianma (=Hpimaw) western Yunnan,China.The type specimens (Holotype) is deposited in the Kunming Institute of Zoology,the Chinese Academy of Sciences.Paratypes (CREDY 287 and CREDY 429) are deposited in the Control and Research Institute of Epidemic of Yunnan. Ochotona nigritia sp.nov.Gong et Wang Holotype:CREDY 97-183,adult,collected on Oct.5,1997,from Pianma,Lushui County,western Yunnan,alt.3200 m. Paratypes:CREDY 97-287,97-429,adults,collected on Oct.7,and Nov.8,1997,from same locality as the holotype. Diagnosis:The new species distingished from all other of genus Ochotona by its especially dark coloration.Summer:dorsal pelage dark blackish with patch of umber-brownished on head and sides of cheek,and of grayish on flank.Ventral pure blackish;Winter pelage pure black dorsally and ventrally.Size medium,LHB 156(153-160) mm,EL 17.3(17-18) mm,LHF 27.3(27-28) mm,GLS 38.2(37.5-38.9) mm,ZW 19.1(18.8-19.1) mm,BW 16.7(15.9-16.7) mm,BH 14.6(14.3-14.9) mm;incisive and palatal foramina completely confluent.Remarks:Dark blackish pelage of the new species is unique in genus Ochotona.The new species belongs to subgenus Ochotona by its incisive and palatal foramina completely confluent on the skull.It differs from many species of sub genus Ochotona (O.macrotis,O.roylei,O.koslowi,O.curzoniae,O.daurica,O.annectens,O.iliensis,O.himalayana,O.gloveri,O.erythrotis) in its small size (GLS <40 mm),and flattened skull in profile.It distingished yet from O.macrotis and O.roylei by its no small oval foramina on the anterior end of the frontal.It differs from O.cansus and O.thomasi in its longer and wide skull (GLS 38.2(37.5-38.9) mm,vs.<36.2 mm;and ZW over 18 mm vs.<16.2 mm). The new species is closely similar to sympatric species (O.forresti,O.thibetana and O.gaoligongensis) in size,no small oval formina on the frontal and the ratio of ZW and GLS of the skull.It distinguished from latter 3 species by its dark black pelage,its rather prominent braincase (ratio of BH and GLS 38.1%-38.3% vs.<37.0%);by its wide basioccipital bone (width of basioccipital bone at carotid cannel 4.1 (3.8-4.3) mm vs.3.2(2.8-3.4) mm in O.forresti,2.7(2.6-2.9) mm in O.thibetana,and 2.4(2.2-2.4) mm in O.gaoligongensis);by its relatively shorter ear(17-18 mm vs.over 20 mm);by its large auditory bulla ［LAB 9.1(8.9-9.2) mm vs.8.3(7.6-8.9) mm］;by its relatively longer bone palate 2.1(1.9-2.2) mm vs.1.3(1.0-1.5) mm］;by its pear shaped incisive-palatal foramina against calabash or violin shaped incisive-palatal foramina (O.forresti and O.gaoligongensis).