Taxonomy and phylogeny of the freshwater tintinnid Tintinnopsis tubuformis Chiang, 1956 (Ciliophora, Oligotrichea) and a proposed synonymization of T. longa nom. corr. Chiang, 1956

Abstract

Tintinnid ciliates are traditionally identified by their loricae; however, increasing evidence indicates that some lorica features (e.g. its length, spiraled structures) are not reliable. The vast majority of tintinnids inhabit the marine pelagial; merely, about thirty species live in freshwater. In the present study, two morphotypes with similar lorica shapes and opening diameters but deviating lorica lengths were isolated from freshwater samples collected at different water temperatures near Chongming Island in the Yangtze Estuary, China. The specimens were studied in vivo and after protargol staining, and their phylogenetic placement was inferred from three ribosomal RNA markers; further, cell division was investigated in the short morphotype. Based on the original descriptions, the longer morphotype is identified as Tintinnopsis longa nom. corr. Chiang, 1956, and the shorter one as Tintinnopsis tubuformis Chiang, 1956. Despite distinct differences in the lorica lengths, the identity of the three molecular markers in both morphotypes suggests conspecificity, which is supported by overlapping ranges in the lorica opening diameters and the length‐independent features of the somatic ciliary pattern (e.g. number of kineties). Hence, we synonymized T. longa nom. corr. with T. tubuformis and neotypified the later species.

When ecological transitions are not so infrequent: independent colonizations of athalassohaline water bodies by Arcellidae (Arcellinida; Amoebozoa), with descriptions of four new species

“…This pattern repeats in molluscs (Aristide and Fernández 2022 ), annelids (Rousset et al 2008 ) and nematodes (Holterman et al 2019 ). Several groups that actually crossed the salinity barrier were unsuccessful in settling terrestrial environments, like Gastrotricha (Kolicka et al 2020 ), Tintinnid ciliates (He et al 2022 ) or Caridean shrimps (Davis et al 2018 ). In summary, when extending to all eukaryotes (microbial or not), the humidity barrier could play a role at least as important as the salinity barrier in the structuration of biodiversity worldwide.…”

A new contribution to the raptorial ciliate genus Lacrymaria (Protista: Ciliophora): a brief review and comprehensive descriptions of two new species from Changjiang Estuary

“…However, little attention has been given to the family Lacrymariidae. A project on ciliate fauna conducted in Changjiang Estuary has led to the discovery of various new or rarely known ciliates (Chen et al, 2022;Han et al, 2022;He et al, 2022;Zhang Z. et al, 2022a,b). As a new contribution, we investigated the phylogeny and taxonomy of two new Lacrymaria species, namely, L. songi sp.…”