Takafumi NakanoEkgachai JeratthitikulTao Thien NguyenSomsak PanhaHiroshima UniversityKyoto UniversityMahidol UniversityVietnamese Academy of Science and TechnologyChulalongkorn University2018-12-112019-03-142018-12-112019-03-142016-05-20Raffles Bulletin of Zoology. Vol.64, (2016), 105-116021724452-s2.0-84971016580https://repository.li.mahidol.ac.th/handle/20.500.14594/40615© National University of Singapore. A new species of the terrestrial haemadipsid genus Tritetrabdella, Tritetrabdella longiducta, from northern Indochina is described. The new species is distinguished from all congeners by the combination of triannulate somite VII, uniannulate somite XXV, three lobes of respiratory auricles in somites XXV-XXVII, 57 friction rays on caudal sucker, male gonopore (in somite XI b5/b6) and female gonopore (in somite XII b5) positions and slightly folded vaginal sac. Phylogenetic analyses using nuclear 18S rRNA and 28S rRNA, in addition to mitochondrial cytochrome c oxidase subunit I markers, confirmed that the new species forms a unique lineage among the known congeners. A key to all the species of Tritetrabdella is provided.Mahidol UniversityAgricultural and Biological SciencesArticleSCOPUS