The Cyclophyllidea comprise the most species-rich order of tapeworms (Platyhelminthes, Cestoda) with, for helminths, perhaps the most severe health impact on wildlife, livestock, and humans. Rodent biodiversity of the Qinghai-Tibet Plateau (QTP) and its surrounding ranges provide a significant reservoir for numerous species of Cyclophyllidea. We collected cyclophyllidean species from QTP and Xinjiang province in China, resolving four unsequenced and likely new species. Phylogenetic construction of partial 18S rDNA, 28S rDNA and mitochondrial ( mt) genes provided high nodal support for the categorisation of the three of the putative new species, assigning each respectively to the genera Hydatigera (ex Eospalax fontainierii), Mesocestoides (ex Neodon irene) and Paranoplocephala (ex Neodon irene). Poor nodal support for the unidentified (‘new’) species collected from pika ( Ochotona curzoniae) in Yushu county, Qinghai province. Combined with the current investigation, the other three cyclophyllidean species found in this study ( Taenia caixuepengi, Taenia crassiceps and Versteria mustelae) may be widely distributed in western China. The phylogenetic reconstructions based on 28S rDNA and cox1- nad1 indicate that some families and genera may require taxonomic revision. Estimates of divergence time based on mt genes showed that the differentiation rate of tapeworms was strongly associated with the rate of change in the biogeographic scenarios caused by the uplift of the QTP, i.e. species differentiation of Cyclophyllidea was driven by host-parasite co-evolution caused by the uplift of QTP. We propose an “out of QTP” hypothesis for the radiation of cyclophyllideans.

The larva of Taeniidae species can infect a wide range of mammals, causing major public health and food safety hazards worldwide. The Qinghai-Tibet Plateau (QTP), a biodiversity hotspot, is home to many species of rodents, which act as the critical intermediate hosts of many Taeniidae species. In this study, we identified two new larvae of Taenia spp., named as T. caixuepengi and T. tianguangfui, collected from the plateau pika (Ochotona curzoniae) and the Qinghai vole (Neodon fuscus), respectively in QTP, and their mitochondrial genomes were sequenced and annotated. Phylogenetic trees based on the mitochondrial genome showed that T. caixuepengi has the closest genetic relationship with T. pisiformis, while T. tianguangfui was contained in a monophyletic group with T. crassiceps, T. twitchelli and T. martis. Biogeographic scenarios analysis based on split time speculated that the speciation of T. caixuepengi (~5.49 Mya) is due to host switching caused by the evolution of its intermediate host. Although the reason for T. tianguangfui (~13.11 Mya) speciation is not clear, the analysis suggests that it should be infective to a variety of other rodents following the evolutionary divergence time of its intermediate host and the range of intermediate hosts of its genetically close species. This study confirms the species diversity of Taeniidae in the QTP, and speculates that the uplift of the QTP has not only a profound impact on the biodiversity of plants and animals, but also that of parasites.