Abstract:

Aims: In the past 20 years, with the rise of molecular biology, there is more and more evidence that extensive cryptic species occupy a high proportion of undiscovered biodiversity. Accurate assessment of endangered taxa diversity is beneficial to better understand the speciation in biodiversity patterns and the process of heterogeneity. It can also contribute to the effective protection and management of biodiversity. Ottelia, grade II plants in the List of the National Key Protected Wild Plants in China, is a pan-tropical aquatic plant group, the Yunnan-Guizhou Plateau and its adjacent areas is an important centre of species diversity in the genus. Due to its high phenotypic plasticity and lack of unambiguous identification characteristics, the taxonomy of the genus has not been well described, greatly limiting the formulation of relevant protections.

Methods: Based on extensive sampling of Ottelia populations in China, we used a Bayesian coalescent method for species delimitation using the multi-locus data set (8 plastid regions and nrITS).

Results: We showed with molecular evidence that in at least 14 Ottelia species in China, all three varieties of O. acuminata should be treated at the species level. Also, there were cryptic species found in O. acuminata and O. jingxiensis. We speculate that the heterogeneous habitats in the karst region and the geographical isolation between the water systems in southwest China may explain the rapid speciation of endemic Ottelia taxa in China.

Conclusion: According to our results, we propose that each taxon (including cryptic species) should be protected as independent protected units.

Key words: Ottelia acuminata, species delimitation, phylogeny, taxonomic treatment