Oxytricha lithofera Foissner, 2016

Min, Kyu-Seok Chae and Gi-Sik, 2022, New record of three oxytrichid ciliates (Ciliophora: Oxytrichidae) from South Korea, Journal of Species Research 11 (4), pp. 287-295 : 288-290

1. Oxytricha lithofera Foissner, 2016 ( Table 1, Figs. 1

and 2 )

Oxytricha lithofera Foissner, 2016: p. 699 ; Luo et al., 2021: p. 1.

Korean name. qǐặšAEǿAEệ

Material examined. Slightly saline soil (1‰), Sacheonsi, Gyeongsangnam-do, South Korea (34°57 ʹ 42.6 ʺ N, 128°02 ʹ 15.2 ʺ E), collected by Kyu-Seok Chae in June 2020 .

Diagnosis of the Korean population. Size in vivo about 100 × 45 μm, ellipsoidal body shape; 2 macronuclear nodules and 1-3 micronuclei; contractile vacuole at the left of mid-body; 21-28 adoral membranelles; cortical granules present; 3 frontal cirri; 4 frontoventral cirri; one buccal cirrus; 3 postoral-ventral cirri; 2 pretransverse and 5 transverse cirri; one left and one right marginal cirral row; 4 dorsal and 2 dorsomarginal kineties; 3 caudal cirri.

Description. Body size 90-110 × 40-50 μm in vivo, 67- 88 × 25-40 μm after protargol preparations ( Table 1). Flexible body outline usually elongated elliptical, both ends rounded ( Fig. 1A ). Two macronuclear nodules, with a size of 11-16× 5-8 μm after protargol preparation ( Fig. 1C ). One to three micronuclei, size about 2 μm diameter after protargol preparation ( Fig. 1C ). Contractile vacuole in left margin of mid-body, about 11 μm in diameter ( Fig. 2A , arrowhead). Colorless cortical granules usually arranged along and in between dorsal kineties ( Fig. 2B ). One or two ring-shaped lithosomes, 4-6 μm in diameter, with wall 0.8-1.2 μm thick, located subapically and/or subterminally ( Figs. 1A , 2A ). Cytoplasm colorless ( Fig. 2C ).

Adoral zone membranelles along about 38% of body length, comprising of 21-33 membranelles ( Figs. 1B , 2C , Table 1). Three frontal cirri, four frontoventral cirri, one buccal cirrus, and three postoral-ventral cirri ( Figs. 1B , 2C , Table 1). Two pretransverse and five transverse cirri ( Figs. 1B , 2C , Table 1). One left (14-21 cirri) and right (15-18 cirri) marginal row, both marginal rows non-confluent posteriorly ( Fig. 1B , Table 1). Four dorsal and two dorsomarginal kineties ( Figs. 1C , 2D , Table 1). Three caudal cirri located at ends of dorsal kineties 1, 2, 4 on posterior end of cell ( Figs. 1C , 2D ).

Figures

Fig. 1. Morphology of Oxytricha lithofera from live (A) and protargol-impregnated (B, C) specimens. A, Ventral view arrowheads denote lithosomes; B, C, Ventral and dorsal view of typical specimen; AZM, adoral zone of membranelles; BC, buccal cirrus; CC, caudal cirri; E, endoral membrane; FC, frontal cirri; LMR, left marginal cirral row; Ma, macronuclear nodules; Mi, micronuclei; P, paroral membrane; RMR, right marginal cirral row; TC, transverse cirri; 1-6, dorsal kineties 1-6; Scale bars: 50μm (A, C).

Fig. 2. Photomicrographs of Oxytricha lithofera from live (A, B) and after protargol impregnation (C, D). A, Ventral view showing litho- somes (arrows) and contractile vacuole (arrowhead); B, Dorsal view showing dorsal bristles and cortical granules; C, D, Ventral and dorsal view of typical specimen; Scale bars: 50μm (A-D).

Fig. 8. Maximum likelihood (ML) phylogenetic tree inferred from 18S rDNA sequences of Oxytrichidae ciliates. The phylogenetic trees show the position of three soil ciliates of Oxytricha lithofera (arrow), Pleurotricha curdsi(arrowhead) and Sterkiella tetracirrata(double-arrowhead). New sequences are shown in bold text. Numbers at nodes indicate the bootstrap values of ML and the posterior probability of BI. Nodes designated by an asterisk (*) correspond to the supports not recovered in the estimated BI tree. The scale bar corresponds to two substitutions per 100 nucleotide positions.