Morpho-molecular Characterization of the Litostomatean Predatory Ciliate Phialina pupula (Müller, 1773) Foissner, 1983 (Haptoria, Lacrymariidae)

Abstract

The morphology and phylogenetic position of a haptorian ciliate, Phialina pupula (Müller, 1773) Foissner, 1983, isolated from microaerobic sandy sediments of the floodplain area of the Boise River, Idaho, U.S.A., were studied using live observation, protargol impregnation, scanning electron microscopy, and the 18S rRNA gene as well as the ITS region. The Boise population of P. pupula is characterized by a size of about 60-130 × 20-50 µm, an elliptical macronucleus with a single micronucleus, highly refractive dumbbell-shaped inclusions scattered throughout the cytoplasm and concentrated in the anterior body half, a single subterminal/terminal contractile vacuole, about 10 µm long rod-shaped extrusomes, and an average of 15 ciliary rows. In phylogenetic analyses, the newly obtained sequences from P. pupula and Lacrymaria olor clustered within the family Lacrymariidae with full to moderate statistical support. Neither the genus Phialina nor the genus Lacrymaria was depicted monophyletic both in the single gene and multigene phylogenetic inferences. Specifically, the genus Phialina was shown as a paraphyletic assemblage containing members of the polyphyletic genus Lacrymaria. This indicates that the phialinid bauplan, i.e., an anterior body end differentiated into a head-like structure directly attached to the trunk, might represent the ground pattern in the family Lacrymariidae. On the other hand, the long highly contractile neck carrying the head-like structure probably evolved later and convergently in multiple Lacrymaria species from Phialina-like ancestors.

Highly divergent morphology but a close molecular phylogenetic relationship between two little‐known ciliate genera Actinobolina and Papillorhabdos (Protozoa: Ciliophora: Litostomatea) with description of two new species

“…The phylogenetic tree, based on the 18S rRNA gene, reveals unstable internal relationships and numerous weakly supported nodes within the order Spathidiida, consistent with previous reports (Chi, Wang, et al., 2021; Huang et al., 2018; Jang et al., 2017, 2022; Jiang et al., 2021; Pomahač et al., 2023; Rajter et al., 2019; Rajter & Vďačný, 2016, 2017; Vďačný et al., 2011, 2014; Yıldız, 2018). Interestingly, although Actinobolina and Papillorhabdos differ in all key features such as general appearance (ellipsoidal with numerous tentacles vs. cylindrical), extrusomes (stored in the tentacles vs. anchored to the cortex), circumoral kinety (present vs. absent), composition of somatic kineties (kinetosome clusters vs. monokinetids), and dorsal brush rows (1 vs. 4), they have an unexpectedly and fully supported phylogenetic relationship in the 18S rRNA gene tree.…”

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

“…The molecular phylogeny of Lacrymaria was initially investigated by sequencing the SSU rRNA gene of L. marina Kahl, 1933(Gao et al, 2008. Subsequently, Rossi et al (2016), Huang et al (2018), andRajter et al (2019) sequenced nine new SSU rRNA gene sequences of the genus and found that Lacrymaria was likely a non-monophyletic genus. However, none of those sequences were reported with the morphological data, which cast doubt on these results.…”

“…Ciliates are excellent indicators for water quality monitoring and play a vital role in the aquatic microbial food web (Wang et al, 2022;Weisse and Montagnes, 2022). Lacrymaria ciliates are common raptorial microorganisms found in aquatic habitats worldwide (Kahl, 1930;Dragesco, 1960Dragesco, , 1965Rajter et al, 2019;Wang et al, 2019). They can be easily identified by the bubble-like head located at the front end of their body, which is covered by short oblique kineties (Lynn, 2008).…”

“…The family Lacrymariidae de Fromentel 1876 includes four genera, namely, Lacrymaria Bory de Saint-Vincent, 1824, Pelagolacrymaria Foissner, 1999, Phialina Bory de Saint-Vincent, 1824, and Phialinides Foissner, 1988(Lynn, 2008. In contrast to other wellstudied haptorians, such as pleurostomatids and spathidiids, research on the Lacrymariidae is limited, and its phylogeny remains unresolved (Foissner, 1988;Foissner and Xu, 2007;Rajter et al, 2019;Pan et al, 2020;Wu et al, 2021Wu et al, , 2022Chi et al, 2022;Zhang G. et al, 2022a,b,c).…”

“…Since the descriptions of most Lacrymaria species are rough and superficial, the species delimitation is understudied. Recent phylogenetic analysis of Haptoria based on either single gene locus or multiple gene loci has shown that Lacrymaria is not monophyletic (Wu et al, 2017;Huang et al, 2018;Rajter et al, 2019;Wang et al, 2019). However, this conclusion is not confident because only 3 out of 53 nominal Lacrymaria species have molecular information, and the DNA sequence that detached from Lacrymaria in gene trees is not reported along with morphometrics (Huang et al, 2018;Rajter et al, 2019).…”