Multi-gene-based investigation on the molecular phylogeny of the hypotrichous family Strongylidiidae(Protista,Ciliophora),with notes on the ontogeny of a new genus and new species

Ciliates in the subclass Hypotrichia have long been difficult to classify as they are one of the most polymorphic and highly differentiated groups,leading to their systematics remaining unresolved.Phylogenetic relationships within the hypotrich family Strongylidiidae have been ambiguous due to discordance between the morphological and genetic data.In this study,a new strongylidiid genus Heterouroleptus is established,mainly based on the novel mode of origin of the ventral cirral rows:left ventral cirral row(LVR)originates from frontal-ventral-transverse cirral anlagen(FVTA)Ⅲ(anterior portion),IV(middle portion),and V(rear portion);right ventral cirral row comes from the entire FVTA VI.A new species,Hetero-uroleptus weishanensis gen.nov.,sp.nov.,is investigated along with the morphometric and molecular data from a population of Strongylidium wuhanense.Eight new sequences and nuclear gene markers(single-gene and multi-gene)are provided to analyze the phylogenetic relationships of strongylidiids,with the COI gene utilized to uncover further genetic information at species level and below.The results reveal that:(1)Strongylidiidae is monophyletic and has a close relationship with Dorsomarginalia;(2)Heterouroleptus gen.nov.forms a clade that is sister to all the other strongylidiids;(3)Hemiamphisiella Foissner,1988 and Pseudouroleptus Hemberger,1985 should not be synonyms,and both genera should be subdivided due to their variable morphological characteristics;(4)LVR originating from three anlagen is a plesiomorphy of Strongylidiidae.The discovery of the origin of the LVR not only contributes to the establishment of the genus Heterouroleptus,but also helps to improve the diagnosis of the family Strongylidiidae.

Exploring the biogeography,morphology,and phylogeny of the condylostomatid ciliates(Alveolata,Ciliophora,Heterotrichea),with establishment of four new Condylostoma species and a revision including redescriptions of five species found in China

Species of the ciliate class Heterotrichea Stein,1859 are a cosmopolitan group of unicellular eukaryotic microorganisms,many of which have been widely used as models in various fields of research such as regenerative biology,functional ecol-ogy,environmental toxicology,and symbiotic behavior.However,species identification in the heterotrich family Condylos-tomatidae,especially the most species-rich and type genus Condylostoma Bory de Saint-Vincent,1824,remains challenging due to incomplete original descriptions,few reliable distinguishing characters,and overlapping features between different species.This study presents an updated revision of Condylostoma and its related genus Condylostomides da Silva Neto,1994 based on descriptions of five species,including nine populations collected from China,using both morphological and molecular methods.The main findings are as follows:(1)43 nominal species and about 130 populations are reviewed,result-ing in the recognition of 30 valid species of Condylostoma and eight valid species of Condylostomides;(2)keys,synonyms,biogeographic distributions and amended/improved diagnoses of all valid species are provided;(3)based on the available data,four new Condylostoma species(C.marinum sp.nov.,C.petzi sp.nov.,C.villeneuvei sp.nov.,and C.microstomum sp.nov.),one new combination(Condylostomides minimus(Dragesco,1954)comb.nov.&nom.corr.),and two corrected names(Condylostoma ancestrale Villeneuve-Brachon,1940 nom.corr.and Condylostomides nigrus(Dragesco,1960)nom.corr.)are suggested;(4)cryptic species are detected and proposed for the first time to form the Condylostoma curvum spe-cies complex;(5)three highly confusing Condylostoma species,C.kris,C.spatiosum,and C.minutum,are redefined for the first time based on modern taxonomic methods;(6)a‘flagship’species,Condylostomides coeruleus,is recorded for the first time from the continent of Asia,substantially expanding its biogeography;(7)ciliature adjacent to the distal end of the paroral membrane within the family Condylostomatidae is uniformly defined as frontal membranelles and is classified into three patterns according to the arrangement of kinetosomes,which serve as important key features.