Trapped on the Roof of the World:taxonomic diversity and evolutionary patterns of Tibetan Plateau endemic freshwater snails(Gastropoda:Lymnaeidae:Tibetoradix)

The high-elevation Tibetan Plateau(western China)is inhabited by a unique,though not particularly species-rich,community of organisms.We explored the species content and evolutionary history of the Tibetan Plateau endemic freshwater snail genus Tibetoradix.Phylogenetic relationships within the genus were reconstructed based on available sequence data.We used a single-rate Poisson Tree Processes approach for species delimitation and compared putative species-level clades with already described taxa.We found that the genus consists of at least 6 species,of which we described 4 as new to science.Shell and soft body morphology was examined and the radula in Tibetoradix was described for thefirst time.Based on ourfindings,the diversification of the genus did not result in a prominent morphological differentiation and a number of species can be regarded as morphologically cryptic.Single species found in different drainage areas indicate relatively good passive dispersal abilities of the snails.The allopatric distribution of the species could result from competitive exclusion between them.The absence of Tibetoradix spp.outside the Tibetan Plateau could be explained by a scenario of an“evolutionary trap”,where adaptations to high elevation conditions prevented the taxa from a successful colonization of lower elevations.

Roots of the taxonomic impediment:Is the“integrativeness”a remedy?

The use of the“integrative approach”for classification of organisms since its formal establishment in 2005 has become a recurrent theme of zoosystematics.A bibliometric survey of the publications on integrative taxonomy of animals,which is aimed at exploring the most popular areas of research and characterizing the practical systematists’attitudes to this new approach,is presented.An analysis of 582 papers,which appeared between 2005 and 2017 in journals indexed by Scopus and the Web of Science Core Collection,has illustrated the gradual growth of the popularity of integrative taxonomy as well as some biases in the representation of higher taxa in“integrated”studies.It has been shown that the“integrative”papers have more chance of appearing in a top-ranking journal and gain relatively more citations as compared with non-integrative papers.The obtained results are discussed in the context of the“taxonomic impediment”problem thought to be a consequence of the institutional crisis of traditional taxonomy,which has been vividly debated over the past decades.