Morphology and 18S rDNA gene sequence of Spirostomum minus and Spirostomum teres (Ciliophora: Heterotrichea) from Rio de Janeiro, Brazil

Abstract

ABSTRACT. Species of Spirostomum Ehrenberg, 1838 are widely used as model organisms in ecological studies of environmental impacts and symbioses between ciliates and human pathogenic bacteria. However, the taxonomy of this genus is confused by the superficiality of the morphological descriptions of its included species, and the use of only a few characters for their differentiation. The present study provides details of total infraciliature, nuclear apparatus, morphometric data and 18S rDNA gene sequences of Spirostomum teres Claparède & Lachmann, 1858 and Spirostomum minus Roux, 1901, isolated from a sewage treatment plant and a freshwater lake in the city of Rio de Janeiro, Brazil, respectively. For the morphological descriptions of S. teres and S. minus, living cells were observed using bright-field and differential interference contrast (DIC) microscopy, the total infraciliature and nuclear apparatus were revealed by staining with protargol, and ciliary patterns were observed also with scanning electron microscopy (SEM). and colorless cytoplasm. Evidence from 18S rDNA sequences confirms the identification of S. teres and suggests the existence of cryptic species closely related to S. minus. The use of silver impregnation technique (protargol) allowed the observation and description of a greater number of characters in S. minus and S. teres, thus assisting the research that require identification of these species.

Spirostomum teres: A Long Term Study of an Anoxic-Hypolimnion Population Feeding upon Photosynthesizing Microorganisms

“…Both in DAPI and protargol treated samples, the ciliature, membranells and morphology of cytostoma were in good agreement with the S. teres Cláparède & Lachmann, 1858 description (López-Ochoterena 1966;Dragesco and Dragesco Kerneis 1986;Foissner et al 1992;Şenler and Yildiz 2004;Fernandes and da Silva-Neto 2013;Boscaro et al 2014;Shazib et al 2016Shazib et al , 2019. However, the macronucleus was found more elongated and curved although not in such extent as for S. yagiui Shigenaka, 1959.…”

First Record of Two Spirostomum Species (Spirostomatidae, Heterotrichida, Heterotrichea) of Ciliates from Jindo Island in Korea

“…The Jindo population of Spirostomum minus closely resembles the original Swiss population (Roux, 1901), British population (Foissner et al, 1992), and Brazilian populations (Fernandes and da Silva Neto, 2013) with respect to ratio of adoral zone membranelles to body length, shape of macronucleus, and ratio of body length to width. However, the Jindo population differs slightly from the Madagascarian population in number of macronucleus nodules (11-16 vs. 24), the German population in ratio of adoral zone of membranelles to body length (40-50% vs. 28-40%), the Brazilian population in body width (35-45 μm vs. 55-115 μm) and color of cortical granules (colorless vs. pale brown), and the European population in number of micronuclei (20-37 vs. up to 20) (Dragesco and Dragesco-Kernéis, 1986;Song and Wilbert, 1989;Fernandes and da Silva Neto, 2013;Boscaro et al, 2014) (Table 2). Typical Spirostomum minus and S. ambiguum are very similar but different with respect to body length (300-800 μm vs. 1,000-4,000 μm) and ratio of adoral zone membranelles to body length (40-50% vs. 65-70%) (Foissner et al, 1992) (Tables 1, 2).…”

Expanded phylogenetic analyses of the class Heterotrichea (Ciliophora, Postciliodesmatophora) using five molecular markers and morphological data

“…Phylogenies based on 18S-rDNA sequences confirmed the close relationship of Anigsteinia and Spirostomum (Shazib et al, 2014). The difference between both genera is that Spirostomum displays body torsion during contraction (Boscaro et al, 2014;Fernandes and da Silva Neto, 2013).…”

“…In Gruberia, the contraction is longitudinal, i.e., along the antero-posterior axis of the body (Dragesco and Dragesco-Kernéis, 1986). In Spirostomum, the paroral membrane is continuous and thickened posteriorly (Dragesco and Dragesco-Kernéis, 1986;Fernandes and da Silva Neto, 2013), whereas in Gruberia, the paroral is fragmented and thickening is absent (Dragesco and Dragesco-Kernéis, 1986;Shazib et al, 2014). Jankowski (1964) speculated that Spirostomum evolved from Gruberia by polymerization of the adoral membranelles.…”