Dysteria monostyla (Ehrenberg, 1838) Kahl, 1931

Wang, Congcong, Qu, Zhishuai & Hu, Xiaozhong, 2019, Morphology and SSU rDNA sequences of four cyrtophorian ciliates from China, with description of a new species (Protista, Ciliophora, Phyllopharyngea), Zootaxa 4664 (2), pp. 206-220 : 212-213

Dysteria monostyla (Ehrenberg, 1838) Kahl, 1931

( Fig. 5 A–E; Table 2 )

Morphological description. Body 40–70 × 30–45 µm in vivo, rectangular to oval in side view ( Fig. 5A ). Two ventrally located contractile vacuoles, one at anterior 1/3 and the other at posterior 1/4 of cell, each with a diameter of about 4 μm and a pulsating interval of about 15 s ( Fig. 5A ). Two nematodesmal rods, each about 25 μm long. Macronucleus ellipsoidal and heteromerous, about 25 × 15 μm in vivo and about 25 × 13 μm after protargol staining ( Fig. 5E ). Micronucleus not detected. Podite about 12 µm long. Cell surface densely covered by bar-shaped ectosymbiotic bacteria (about 4 μm long; Fig. 5B ). Fine transverse stripes at mid-body on surface of both lateral plates ( Fig. 5B ).

Invariably five right kineties with densely arranged basal bodies including two frontoventral kineties with 119–128 basal bodies each ( Fig. 5C ). Five to eight left kineties ( Fig. 5E ). Terminal fragment consists of 9–11 basal bodies ( Fig. 5C ). Equatorial fragment composed of 5–19 kinetosomes ( Fig. 5C ). Oral apparatus typical of genus ( Fig. 5D ).

SSU rRNA gene sequence and phylogenetic position. The GenBank accession number, length, and G + C content are MK 882888 , 1,677 bp, and 44.25%, respectively. The closest related Dysteria species is Dysteria compressa ( KC 753491 ) with a 99.8% sequence similarity. In phylogenetic trees ( Fig. 6 ), D. monostyla first groups with D. compressa KC753491 , then clusters with D. brasiliensis FJ870067 with high support values ( ML /BI, 99%/1.00).

Figures

FIGURE 5. Photomicrographs of Dysteria monostyla (A–E) and D. crassipes (F–I) from live (A, B, F, and G) and after protargol impregnation (C–E and H, I). A. Left lateral view of a representative individual, arrowheads show contractile vacuoles (CV). B. Cell surface, arrow refers to the transverse stripe, arrowhead shows bar-shaped ectosymbiotic bacteria. C. Left lateral view of ciliary pattern. D. Anterior part of cell. E. Ventral view of mid-body. F. Left lateral view of a representative individual, arrows point to contractile vacuoles. G. Rod-shaped ectosymbiotic bacteria attached on cell surface (arrowheads). H, I. Left lateral views of ciliature.Abbreviations: Co—circumoral kineties; EF—equatorial fragment; FvK—frontoventral kineties; Lfleft frontal kineties; LK—left kineties; Ma—macronucleus; Pr—preoral kinety; RK—right kineties; TF—terminal fragment. Scale bars: 30 μm (A, C, F and H).

FIGURE 6. Phylogenetic tree of Maximum-likelihood (ML) based on small SSU rRNA gene sequences with Bayesian inference (BI) tapped on it. The four new sequences in the present paper are highlighted in bold. Numbers at nodes show ML bootstrap values and the BI posterior probabilities (ML/BI). Values with full support (ML/BI, 100/1.00) are marked with solid circle. The scale bar corresponds to 5 substitutions per 100 nucleotide positions. * Guangdong population of Chlamydodon bourlandi, ** misidentification, should be Chlamydodon bourlandi.