Ultrastructure of Diophrys appendiculata and new systematic consideration of the euplotid family Uronychiidae(Protista,Ciliophora)

The ultrastructure of ciliates carries important cytological,taxonomical,and evolutionary signals for these single-celled eukaryotic organisms.However,little ultrastructural data have been accumulated for most ciliate groups with systematic problems.In the present work,a well-known marine uronychiid,Diophrys appendiculata,was investigated using electron microscopy and a comparison with,and a discussion considering,phylogenetic analyses were made.The new findings primarily show that:(i)this species lacks the typical alveolar plate,bears cortical ampule-like extrusomes,and has microtubular triads in the dorsal pellicle,and thus exhibits some ultrastructural features in common with most of its previously studied congeners;(ii)each adoral membranelle before the level of frontal cirrus II/2 contains three rows of kinetosomes and each membranelle after the level of frontal cirrus II/2 contains four rows,which might be related with morphogenesis and could be considered as a distinctive character of Diophrys;(iii)some structural details of the buccal field,such as the extra-pellicular fibrils,pellicle,pharyngeal disks and microtubular sheet,were documented.In addition,based on the ultrastructural comparison of representatives,we discuss the differentiation between the subfamilies Diophryinae and Uronychiinae.A hypothetical systematic relationship of members in the order Euplotida based on a wide range of data is also provided.

Hypotrichidium tisiae(Gelei,1929)Gelei,1954:a unique hypotrichid ciliate having a highly specialized developmental pattern during binary division

In sharp contrast to their pelagic relatives,the oligotrichs,the overwhelming majority of hypotrich ciliates inhabit the benthos.Only a few species,including those of the genus Hypotrichidium Ilowaisky,1921,have adapted to a planktonic lifestyle.The ontogenetic mode of the highly differentiated ciliate,Hypotrichidium tisiae(Gelei,1929)Gelei,1954,is unknown.In this study,the interphase morphology and the ontogenetic process of this species are investigated.Accordingly,the previously unidentified ciliary pattern of Hypotrichidium is redefined.The main morphogenetic features are as follows:(1)The parental adoral zone of membranelles is inherited completely by the proter and the oral primordium of the opisthe arises in a deep pouch.(2)Five frontoventral cirral anlagen(FVA)are formed:FVA I contributes to the single frontal cirrus,FVA II–IV generate three frontoventral cirral rows,FVA V migrates and forms postoral ventral cirri.(3)All marginal cirral row anlagen develop de novo:each of the two left anlagen forms a single cirral row,while the single right anlage fragments into anterior and posterior parts.(4)Two dorsal kinety anlagen occur de novo,with the right one fragmenting to form kineties 2 and 3.(5)Two long caudal cirral rows are formed at the ends of dorsal kineties 1 and 3.On the basis of the morphogenetic features and phylogenetic analyses,the assignment of Hypotrichidium to the family Spirofilidae Gelei,1929 within Postoralida is supported.The establishment of separate families for the slender“tubicolous”spirofilids and the highly helical spirofilids is also validated.

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

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.