Widespread Occurrence of Two Planktonic Ciliate Species (Urotricha, Prostomatida) Originating from High Mountain Lakes

Abstract

Ciliates of the genus Urotricha are widely distributed and occur in almost any freshwater body. Thus far, almost all species have been described from morphology only. Here, we applied an integrative approach on the morphology, molecular phylogeny and biogeography of two species isolated from high mountain lakes in the Central Alps, Austria. As these remote lakes are known to have water temperatures <15 °C, our hypothesis was that these urotrichs might prefer ‘cold’ environments. We studied the morphological details from living and silver-stained individuals, and their molecular sequences (ribosomal operon, ITS), and screened available datasets for their biogeography. The two Urotricha species resembled morphological features of several congeners. An accurate species assignment was difficult due to several overlapping characteristics. However, we tentatively attributed the investigated species to Urotricha nais and Urotricha globosa. The biogeographic analyses revealed their occurrence in Europe, Africa and Asia, and no correlations to (cold) temperatures were found. Our findings suggest that these two urotrichs, originating from two cold and remote habitats, are probably cryptic species well adapted to their harsh environment.

FISHing for ciliates: Catalyzed reporter deposition fluorescence in situ hybridization for the detection of planktonic freshwater ciliates

“…indicated that the genus-specific probe likely covered most members of this genus in Lake Zurich. One reason for this encouraging finding are the recently published 18S rRNA gene sequences of five Urotricha species ( Frantal et al, 2022 ; Sonntag et al, 2022 ), that were included in the design of probe Uro-all-651. At the same time, the poor agreement between QPS and CARD-FISH in the sample from April 8, 2020 indicates that not all Urotricha species found in Lake Zurich may be covered by the probe.…”

“…Thus, CARD-FISH could be a powerful tool for studying the in situ food preferences of, e.g., the omnivorous genus Urotricha . Representatives of this genus are widespread and abundant inhabitants of freshwater environments ( Müller, 1989 ; Posch et al, 2015 ; Šimek et al, 2019 ; Frantal et al, 2022 ; Sonntag et al, 2022 ), but little is known about their feeding strategies in situ ( Müller et al, 1991b ; Sonntag et al, 2006 ; Qu et al, 2021 ). In addition to food selectivity, CARD-FISH also provides the potential to further examine the symbiotic relationships within eukaryotic and between eukaryotic and prokaryotic microbes ( Chambouvet et al, 2008 ; Dirren and Posch, 2016 ; Lepère et al, 2016 ).…”

“…All nine selected ciliate species originate from freshwater habitats ( Figure 1 ; Table 1 ). Species identification was done with living and protargol-stained (QPS, Skibbe, 1994 ; Pfister et al, 1999 ) specimens using different identification keys ( Foissner et al, 1994 , 1999 ) and recently published work ( Frantal et al, 2022 ; Sonntag et al, 2022 ). Taxonomic classification was updated according to Lynn (2008) .…”

“… a Detailed description in Frantal et al (2022) . b Detailed description in Sonntag et al (2022) . c Cultivated by Lubomír Adamec, Institute of Botany CAS, Section of Plant Ecology, Třeboň 379 82, Czech Republic.…”

Morphological and molecular examination of the ciliate family Lagynusidae (Protista, Ciliophora, Prostomatea) with descriptions of two new genera and two new species from China

“…However, most prostomateans have only cursory original descriptions based exclusively on observations of live cells, with most of these occurring well before the molecular era (Carey 1992 ; Dragesco 1960 ; Kahl 1930 ). Only a handful of species have benefited from descriptions using modern techniques (Foissner 2021 ; Frantal et al 2022 ; Jiang et al 2021b , 2022 ; Sonntag et al 2022 ). There are also some ultrastructural studies of this group, which revealed details of several important characteristics such as the brosse and the extrusomes (Bardele 1999 ; Hiller 1991 , 1992 , 1993 ; Hiller and Bardele 1988 ; Lipscomb and Riordan 2012 ).…”