Characterization of a Novel Hypotrich Ciliate From Heavy Metal-Contaminated Industrial Outlet in Onsan, Ulsan, South Korea.

Santosh Kumar,Daizy Bharti,Shahed Uddin Ahmed Shazib,Mann Kyoon Shin

doi:10.3389/fmicb.2021.761961

Santosh Kumar, Daizy Bharti + Show 2 more

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https://doi.org/10.3389/fmicb.2021.761961

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Abstract

Very few studies exist on the description of protozoan ciliates from industrially contaminated sites. In this study, we report a description of a novel hypotrich ciliate isolated from water samples collected from an industrially contaminated outlet in Onsan, Ulsan, South Korea. The oxytrichid ciliate, Histriculus tolerans n. sp., was investigated using live observation and protargol impregnation. The morphology, morphogenesis, and molecular phylogeny inferred from small-subunit (SSU) rRNA gene sequences were studied. The new species is mainly characterized by a cell size of about 70 × 40 μm in vivo, two elongate ellipsoidal macronuclear nodules and one or two micronuclei, adoral zone of about 51% of body length with 32 membranelles on average, about 34 cirri in the right and 24 cirri in the left marginal row, 18 frontoventral transverse cirri, six dorsal kineties including two dorsomarginal rows, and dorsal kinety 1 with 26 bristles. Morphogenesis is similar to that of the type species, i.e., Histriculus histrio, except that oral primordium does not contribute to anlage II of the proter. Phylogenetic analyses, based on small-subunit rRNA gene sequences, consistently place the new species within the family Oxytrichidae, clustering with H. histrio.

Highlights

The genus Histriculus Corliss, 1960, is largely confined to freshwater and marine habitats with type species, i.e., Histriculus histrio, having a cosmopolitan distribution
The genus Histriculus contains six species that should be compared with H. tolerans, namely, H. histrio, Histriculus sphagni (Stokes, 1891) Corliss, 1960; Histriculus complanatus (Stokes, 1887) Corliss, 1960; Histriculus minimus (Grolicre, 1975) Berger and Foissner, 1997; H. vorax (Stokes, 1891) Corliss, 1960; and Histriculus similis (Quennerstedt, 1867) Corliss, 1960
Except for the type species, i.e., H. histrio, the description of the other species is mainly based on live observations, and detailed reinvestigations based on standard methods, 3http://water.nier.go.kr especially live observations and protargol impregnation, were recommended by Berger (1999)

Summary

Introduction

The genus Histriculus Corliss, 1960, is largely confined to freshwater and marine habitats with type species, i.e., Histriculus histrio, having a cosmopolitan distribution. The genus is mainly characterized by undulating membranes in Oxytricha pattern, one right and one left marginal cirral row, confluent marginal rows at the posterior end, six dorsal kineties, and absence of caudal cirri. Berger (1999), in his detailed revision of the oxytrichids, assigned six species to the genus; detailed morphology and morphogenesis, as well as gene sequences, have been reported mainly for the type species, i.e., H. histrio (Müller, 1773), Corliss, 1960. The morphology, though poorly described, and morphogenesis with endogenous bud formation have been reported for Histriculus vorax (Stokes, 1891) Corliss, 1960. Berger (1999) recommended detailed reinvestigations of the remaining species of the genus. The morphology, though poorly described, and morphogenesis with endogenous bud formation have been reported for Histriculus vorax (Stokes, 1891) Corliss, 1960. Berger (1999) recommended detailed reinvestigations of the remaining species of the genus.

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