Genetics and morphology of the genus Tritetrabdella (Hirudinea, Haemadipsidae) from the mountainous rain forests of Sabah, Borneo, reveal a new species with two new subspecies

Blood-feeding terrestrial leeches of the family Haemadipsidae are a notorious part of the invertebrate diversity in Asian and Australian rain forests. All hitherto published records of terrestrial leeches of Borneo belong to the genus Haemadipsa. Here, a second, poorly known haemadipsid genus is reported from Mount Kinabalu and Crocker Range National Park. The individuals were barcoded and compared to sequences available in GenBank. The results show that the genus Tritetrabdella has representatives in the Indochinese and the Sundaic bioregions. All six specimens from Borneo are from a single new Tritetrabdella lineage, T. kinabaluensis spec. nov. Within the Bornean lineage, two groups differing 4-5% in the COI barcoding sequence were identified. Because 1) it is probable that haemadipsid COI is subjected to base pair substitution rates of 2.5% per Ma, 2) COI protein sequences were the same within the Bornean material, 3) color can change as a response to the environment, 4) the lineages inhabit different altitudes in separate areas and 5) only six individuals were found, a conservative approach was taken and the groups were tentatively given subspecies status: T. k. kinabaluensis ssp. nov. and T. k. inobongensis ssp. nov. The ecology and the conservation status of the Bornean Tritetrabdella warrant urgent assessment because the genus Tritetrabdella is considered as mainly feeding on amphibians and probably small mammals, and thus can be predicted to be sensitive to climatic fluctuations, forest disturbances and fragmentation, and amphibian decline.