The neotypification of Frontonia vernalis (Ehrenberg, 1833) Ehrenberg, 1838 and the description of Frontonia paravernalis sp. nov. trigger a critical revision of frontoniid systematics

Biodiversity of freshwater ciliates (Protista, Ciliophora) in the Lake Weishan Wetland, China: the state of the art

Ciliates are core components of the structure of and function of aquatic microbial food webs. They play an essential role in the energy flow and material circulation within aquatic ecosystems. However, studies on the taxonomy and biodiversity of freshwater ciliates, especially those in wetlands in China are limited. To address this issue, a project to investigate the freshwater ciliates of the Lake Weishan Wetland, Shandong Province, commenced in 2019. Here, we summarize our findings to date on the diversity of ciliates. A total of 187 ciliate species have been found, 94 of which are identified to species-level, 87 to genus-level, and six to family-level. These species show a high morphological diversity and represent five classes, i.e., Heterotrichea, Litostomatea, Prostomatea, Oligohymenophorea, and Spirotrichea. The largest number of species documented are oligohymenophoreans. A comprehensive database of these ciliates, including morphological data, gene sequences, microscope slide specimens and a DNA bank, has been established. In the present study, we provide an annotated checklist of retrieved ciliates as well as information on the sequences of published species. Most of these species are recorded in China for the first time and more than 20% are tentatively identified as new to science. Additionally, an investigation of environmental DNA revealed that the ciliate species diversity in Lake Weishan Wetland is higher than previously supposed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-022-00154-x.

Taxonomy and molecular phylogeny of a new freshwater ciliate Frontonia apoacuminata sp. nov. (Protista, Ciliophora, Oligohymenophorea) from Qingdao, PR China

The morphology and ciliature of a new freshwater ciliate, Frontonia apoacuminata sp. nov., isolated from an artificial pond in Qingdao, PR China, were investigated using live observation and silver staining methods. The main features separating F. apoacuminata sp. nov. from its congeners are as follows: a broad elliptical body that is slightly pointed at the posterior end, four ophryokineties, one or two spherical micronuclei of a 'compact' type, a dorsally positioned contractile vacuole, and peniculi 1-3 each with five kinetosome rows though the left-most two rows in peniculus 3 are extremely shortened (with only two or three kinetosomes each). Additionally, an improved diagnosis of F. acuminata is provided. Phylogenetic analyses based on the small subunit ribosomal RNA (SSU rRNA) gene show that F. apoacuminata sp. nov. clusters with F. atra, F. minuta, F. acuminata and F. terricola. These five species group with Disematostoma, Marituja and Stokesia rather than with other Frontonia species, causing polyphyly of the genus Frontonia.